General Description Features - SENSOR+TESTSymbol Parameter Min. Typ. Max. Unit tON Power-up rise time for VDD 1 10 ms tINIT Start-up time 100 ms tOFF Power drop-down time for VDD 1

DATASHEET – epc600

Time-of-flight range-finder chip

General DescriptionThe epc600 chip is a general purpose, monolithic, fully integrated photoelectric CMOS device for optical distance measurement and object detection. Its working principle is based on the three-dimen-sional (3D) time-of-flight (TOF) measurement.

The system-on-chip (SOC) contains:■ A full data acquisition path with the driver for the LED, the photo-

receiver, the signal conditioning, the A/D converter and the signal processing.

■ An on-chip controller managing the data acquisition and the data communication.

■ A 2-wire interface for the command and data communication.

■ A supply-voltage power management unit.

Together with a tiny microprocessor (e.g. PIC 10F206) and few ex-ternal components, a fully functional TOF range-finder can be built.

The working principle is based on the elapsed time-of-flight (TOF) of a photon (modulated light) emitted by the transmitter (LED), re-flected back by the object to the photosensitive receiver.

The very high photosensitivity allows operating ranges up to sev-eral meters and an accuracy down to a centimeter depending on the lens and the illumination power.

Features■ Complete data acquisition system for distance measurement or

object detection on chip. Allows for minimum part count designs.■ On-chip high power LED driver.

■ Easy to use operation in combination with a tiny microprocessor.

■ Absolute distance measurement with digital data output.

■ Integrated signal-processing.

■ High sensitivity and resolution for measured distances up to 15m.

■ Response time of less than 1ms possible.

■ Digital data output with 12 bit distance data and 4 bit quality data.

■ Excellent ambient light suppression up to >100kLux.

■ Integrated ambient light meter (“Luxmeter”)e.g. for brightness control or dimmer functions.

■ Voltage supply with low power consumption.

■ Easy to use 2-wire interface with simple command set.

■ Fully SMD-compatible flip-chip CSP24 package with very small footprint.

Possible Applications■ Light barrier with powerful ambient light suppression

■ People and object counting sensor

■ Door opening and safety sensor

■ Limit and proximity switch

■ Machine control and safety sensor

■ Water tap and toilet flushing sensor

■ Single spot parking sensor

■ Distance measurement gauge

Functional Block Diagram

Controller

Correlator

PhasedetectorPhase shifter

Signal-processing

LED driverModulator

Voltageregulator

2-wireserial

interface

RAMEEPROM

CX1

CX2

XTAL

VDD 8.5V

SCLK

SDATA

LED

LEDF

AD

VDDBS -3.0V

Figure 1: epc600 on-chip data acquisition system for range-finders

© 2012 ESPROS Photonics CorporationCharacteristics subject to change without notice

1 / 25 Datasheet epc600 - V0.3www.espros.ch

Table of ContentsGeneral Description.............................................................................................................................................................................................1Features.............................................................................................................................................................................................................. 1Possible Applications...........................................................................................................................................................................................1Functional Block Diagram................................................................................................................................................................................... 1Absolute Maximum Ratings (Note 1, 2) ............................................................................................................................................................. 3Operating Ratings............................................................................................................................................................................................... 3Electrical Characteristics.....................................................................................................................................................................................3Timing and optical Characteristics...................................................................................................................................................................... 4Other Parameters................................................................................................................................................................................................5Pin Configuration.................................................................................................................................................................................................6Layout information (all measures in mm, )..........................................................................................................................................................7

CSP-24 Package.......................................................................................................................................................................................... 7Design precautions: EMC shielding..............................................................................................................................................................7Ambient Light (Backlight)..............................................................................................................................................................................7

Reflow Solder Profile...........................................................................................................................................................................................7Ordering information............................................................................................................................................................................................8Functional Description.........................................................................................................................................................................................9

1. Operation.................................................................................................................................................................................................. 91.1. Introduction............................................................................................................................................................................................ 91.2. General overview...................................................................................................................................................................................91.3. Operational mode................................................................................................................................................................................ 101.3.1. Distance measurement.....................................................................................................................................................................101.3.2. Sensitivity, integration time and operating range ..............................................................................................................................111.3.3. Ambient-light suppression................................................................................................................................................................ 121.3.4. Quality of the measurement result ....................................................................................................................................................121.3.5. Ambient-light measurement (“Luxmeter”).........................................................................................................................................131.3.6. Temperature metering.......................................................................................................................................................................131.3.7. Calibration and compensations........................................................................................................................................................ 131.3.8. Extended operating range................................................................................................................................................................ 131.3.9. Measurement sequence................................................................................................................................................................... 131.3.10. Multi range-finder application......................................................................................................................................................... 142. Hardware Design.................................................................................................................................................................................... 152.1. General Hardware Configuration.........................................................................................................................................................152.2. Power Supply, Clock and Mode setting............................................................................................................................................... 152.3. On-chip LED driver.............................................................................................................................................................................. 16Short range application design................................................................................................................................................................... 16Mid range application design......................................................................................................................................................................162.4. External LED driver..............................................................................................................................................................................16What performance can be achieved?.........................................................................................................................................................172.5. 2-wire interface.................................................................................................................................................................................... 18SCLK line.................................................................................................................................................................................................... 18SDATA line.................................................................................................................................................................................................. 183. Instruction Set.........................................................................................................................................................................................193.1. 2-wire serial interface...........................................................................................................................................................................193.2. Commands & responses..................................................................................................................................................................... 193.2.1. Command: Commands & Integration times..................................................................................................................................... 203.2.2. Response: Distance & Quality..........................................................................................................................................................203.2.3. Response: Ambient-light level .......................................................................................................................................................... 213.2.4. Response: Temperature................................................................................................................................................................... 213.3. Communication tasks.......................................................................................................................................................................... 213.3.1. Measurement sequence (Distance or ambient-light) ....................................................................................................................... 213.3.2. Read sequence (Temperature) .........................................................................................................................................................213.3.3. Error detection by the microprocessor ............................................................................................................................................. 213.3.4. Reset sequence................................................................................................................................................................................213.3.5. Error detection by the epc600 chip ...................................................................................................................................................223.3.6. Cycle times & reaction time.............................................................................................................................................................. 22Integration time tINT................................................................................................................................................................................... 22Duty cycle of the modulation signal............................................................................................................................................................ 22Measurement time tMEAS..........................................................................................................................................................................22Communication time tCOM.........................................................................................................................................................................23Measurement cycle time tCYCLE...............................................................................................................................................................23Data processing time tPROCESS.............................................................................................................................................................. 23Reaction time tREACTION......................................................................................................................................................................... 23LED on-time tLED-ON and LED duty cycle................................................................................................................................................234. Optical Design.........................................................................................................................................................................................24Photosensitive area.................................................................................................................................................................................... 24Signal sensitivity......................................................................................................................................................................................... 24Ambient-light suppression.......................................................................................................................................................................... 24Operating range.......................................................................................................................................................................................... 24

IMPORTANT NOTICE.......................................................................................................................................................................................25



Absolute Maximum Ratings (Note 1, 2) Operating RatingsSupply Voltage VDD -0.5V to +9.5V Operating temperature (TA) -20°C to +65°C

Voltage to any pin except VDD according voltage class VSC (Note 3)

-0.3V to VSC+0.3V Humidity, non-condensing 5% to 95%

Storage temperature (TA) -65°C to +150°C

Soldering Lead Temperature (TL), 4 sec +260°C

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating conditions indicate condi -tions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see Electrical Characteristics.

Note 2: This is a highly sensitive CMOS mixed signal device with an ESD rating of JEDEC HBM class 2 (<2kV). Handling and assembly of this device should only be done at ESD protected workstat ions.

Note 3: For voltage classes VSC refer to 5 and 4.

Electrical CharacteristicsOperational Ratings, unless otherwise specified. typ.: V DD = 8.5V, TA = +25°C

Symbol Parameter VSC Min. Typ. Max. Unit

VDD Supply voltage 8.5V +8.0 +8.5 +9.0 V

VPP Ripple on supply voltage VDD, peak-to-peak 8.5V 100 mV

IDD Average Supply current, average DC, excl. LED driver current 8.5V 20 mA

IDD Peak Supply current, peak, excl. LED driver current 8.5V 30 mA

VDDBS Bias voltage -3.0V -2.7 -3.0 -4.0 V

IDDBS Bias current -3.0V 1.0 mA

VLED Max. voltage at pin LED 5.0V 5.0 V

ILED1ON Sink current at LED 5.0V 180 mA

VLED-ON Forward voltage at LED, @ ILED-ON = 180mA 5.0V 200 mV

VLEDF-AC Input signal amplitude at LEDF, peak-to-peak 5.0V 0.5 5.0 V

VLEDF Input signal range at LEDF 5.0V 0.0 5.0 V

ILEDF Input leakage current at LEDF 5.0V 1.0 μA

VDigital-OH Output voltage high at SDATA 5.0V 4.5 5.2 V

VDigital-OL Output voltage low at SDATA 5.0V 0 0.5 V

IDigital-OH Source current DC at SDATA, average 5.0V 0.1 mA

IDigital-OL Sink current DC at SDATA 5.0V 8.0 mA

CDigital-Out Output load capacitance 5.0V 30 pF

VDigital-IH Input voltage high at SDATA and SCLK 5.0V 4.0 5.0 V

VDigital-IL Input voltage low at SDATA and SCLK 5.0V 0 1.0 V

IDigital-In Input leakage current DC without pull-up/-down resistor 5.0V 1.0 μA

CDigital-In Input capacitance 5.0V 3 pF

RUP or RDOWN Pull up or pull down resistor 5.0V 30 66 kΩ

Table 1: Electrical characteristics



Timing and optical CharacteristicsOperational Ratings. typ.: VDD = 8.5V, TA = +25°CIllumination: λ = 850±50nm, AOI = 0°, Modulation contrast = 100%, LED modulation frequency = 10MHz, Inte gration time = 103 μsec,Object: constant object signal 25% SAC max < SAC < 75% SAC max, constant distance in 10 to 90% of operation range, - or unless otherwise specified.

Symbol Parameter Min. Typ. Max. Unit

tON Power-up rise time for VDD 1 10 ms

tINIT Start-up time 100 ms

tOFF Power drop-down time for VDD 1 10 ms

fXTAL Center frequency of oscillator (crystal) 4 MHz

ΔfXTAL Deviation to center frequency of oscillator(any deviation is added as a linear distance error)

±100 ppm

ΔφXTAL Phase jitter of oscillator peak-to-peak (Cycle to cycle) 50 ps

fSCLK 2-wire interface clock frequency of SCLK 10 MHz

tSCLK 2-wire interface cycle time of SCLK = 1/fSCLK 100 ns

tH / tL 2-wire interface HIGH and LOW period of SCLK (refer to 7) 50ns 1.0ms ns

fMOD LED modulation frequency (Pin LED), see 15 0.625 20 MHz

tLED-rise/fall Required rise/fall time of the illumination LED at pin LED, @ 50ohm loadRemark: Use high speed LEDs with short switching times(e.g. Stanley DNK5306, Osram SFHSFH4059 Vishay VMB2000, etc.)

12 ns

ASENSOR Photosensitive area of the sensor 320x320 μm

SAC-PP Dynamic AC range of the receiver electronics:Input AC illumination power, peak-to-peak, refer to 3 and 15

16016.4

nW/mm2

nW

SDC Ambient-light suppression 303

W/m2

μW

SNF Photon shot noise floor (dark current) 160 μW/m2

λmax Peak wavelength for maximum sensitivity, see 2 850 nm

λ Operating wavelength range 550 1'000 nm

η Quantum efficiency @ λ = 850nm, AOI = 0° 90 %

φ50% Half angle, see 3 ±60 deg

tINT Integration time; programmable in 16 binary steps (see 15) 1.60 52'500 μs

tMEAS Measurement time 0.261 0.665 210 ms

DR Dynamic range @ a fixed integration time@ using an integration time range: 25.6μs – 26.3ms@ using a full range of integration times

3280

110

dBdBdB

DUA Operating range; unambiguity @10MHz LED modulation frequency 15.0 m

ΔDRES Distance resolution @10MHz LED modulation frequency 0.5 cm

ΔD Distance noise; 1σ; calibrated; depending on light power, integration time, lens, etc.

±1 cm

DOFFSET Distance offset compensation by external microprocessor ±DUA

ΔDDRIFT Distance drift, temperature range from -20°C to +65°C 0.1 %/°K

Table 2: Timing and optical characteristics



Other ParametersOperational Ratings. typ.: VDD = 8.5V, TA = +25°CIllumination: λ = 850±50nm, AOI = 0°, Modulation contrast = 100%, LED modulation frequency = 10MHz, Inte gration time = 103 μsec,Object: constant object signal 25% SAC max < SAC < 75% SAC max, constant distance in 10 to 90% of operation range, - or unless otherwise specified.

Sensitivity epc600 with bandpass filter without filter

integration time:103μs

640nm± 27.5nm

860nm± 32.5nm

940nm± 30nm

sunlightequivalent

max. AC sensitivity SAC 210 nW/mm2 160 nW/mm2 210 nW/mm2

min. ambient-light suppression SDC

40 W/m2 53 klx

30 W/m2 52 klx

40 W/m2 145 klx

Table 3: Sensitivity and ambient-light suppression vs. wavelength

500 600 700 800 900 1000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Wavelength [nm]

Re

lativ

e S

en

sitiv

ity

0 10 20 30 40 50 60 70 80 901.00

10.00

100.00

500nm 630nm 850nm 950nm

Angle of incidence (deg)

Ref

lect

ance

(%

)

Figure 2: Relative spectral sensitivity (Sλ)Sensitivity SAC vs. wavelength

Figure 3: Reflectance vs. illumination angle (AOI)

500 600 700 800 900 1000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

wavelength [nm]

quan

tum

effi

cien

cy

Figure 4: Quantum efficiency for photons



Pin Configuration

Top View

17

1 2 3

VDDCPLEDLEDF

VREFGNDMVDDT

5

10

6

20

19

18

7

8

9

VDDCORE

XTAL1XTAL2

24 23

2221

16 15 11

VDDPLL VDD

GNDLED

GNDAGND

GNDPLL

VDDIO

VDDPX

VDDHPX

4

NC3

VDDBS

1.8V

5V

8.5V

10V

12V

-3V

Voltage classes

13 1214

SDATA

SCLK

NC1

NC2

LED

NC3

LEDF

VREF

VDDIO

VDDHPX

VDDPX

VDDCP

VDDBS

XTAL1

XTAL2

GNDM

VDDT

SDATA

SCLK

NC2

NC1

VDDPLL

VDDCORE

GNDLEDGNDPLLGNDAGND

VDD

epc600

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21 22 2324

Figure 5: Pin configuration Figure 6: Schematic symbol

Pin Name Pin No. Type VSC Description

SDATA 19 DOUTDIN

+5V Serial data, bidirectional data transmission of the 2-wire interface

SCLK 20 DIN +5V Serial clock input SCLK of the 2-wire interface

LED 12 AOUT +5V LED driver output, high current, open drain

LEDF 14 AIN +5V LED modulation feedback input (delay compensation for external components)

XTAL1 15 AIN +1.8V Oscillator input

XTAL2 15 AOUT +1.8V Oscillator output

VDD 10 SUPPLY +8.5V Power supply +8.5V

VDDCORE 2 SUPPLY +1.8V Decoupling of internal digital core supply +1.8V

VDDPLL 17 SUPPLY +1.8V Decoupling of internal PLL supply +1.8V

VREF 5 SUPPLY +5V Attention: Do not connect this pin

VDDIO 7 SUPPLY +5V Decoupling of the internal internal I/O supply +5V

VDDPX 8 SUPPLY +5V Decoupling of the internal pixel reference voltage +5V

VDDHPX 9 SUPPLY +10V Decoupling of the internal pixel reference voltage +10V

VDDCP 11 SUPPLY +12V Filter capacitor pin for the charge pump circuit +12V

VDDBS 6 SUPPLY -3V Power supply: Bias voltage -3.0V

VDDT 3 DIN +5V Connect to +5V.

GND 21 SUPPLY --- Ground for digital circuitry +1.8V

GNDA 22 SUPPLY --- Ground for analog circuitry, charge pumps and +5V I/O circuit

GNDPLL 24 SUPPLY --- Ground for PLL

GNDLED 23 SUPPLY --- Ground for LED driver

GNDM 4 DIN +5V Connect to GND.

NC1 18 +5V Attention: Do not connect this pin



Table 4: Pin function descriptions

Abbreviations to 4:

VSC Supply class for matching components and I/O voltage levelsDOUT Digital outputDIN Digital inputAOUT Analog outputAIN Analog input



Layout information (all measures in mm,

<Partname> <x000 000>

<Name> <Data>

M 1:1 DIN A4

<Name>

Part Name Part No.

Designed

Approved

Scale

Page

Th

is d

oc

um

en

t is

co

nfi

de

ntia

l an

d p

rote

cte

d b

y la

w a

nd

inte

rna

tion

al t

rade

s.

It m

ust

no

t be

sh

ow

n t

o a

ny t

hird

pa

rty

no

r be

co

pie

d in

an

y f

orm

with

ou

t o

ur

wri

tten

pe

rmis

sion

.

File:

1

26.02.2009

)

CSP-24 Package

0.125

0.450

0.200

0.450

0.20

0

2.65

0 ±0

.1

2.650 ±0.1

1.325

1.32

50.

050

0.23

0 ±0

.023

Photosensitive areaon the backside of the chip

Circuit side (Frontside)

Pin 1

Solder ballsSn97.5Ag2.5

0.320

0.45

00.

450

0.32

0

0.450 0.150

0.4

50

2.6

50

±0

.1

2.650 ±0.1

Pin 1

∅ 0.3000.450

no solder stop inside this area

Via GNDmin. ∅ 1.00

Solder stop∅ 1.40

Hole∅ 0.50 - 0.60

0.4

50

0.2

00

0.200

Figure 7: Mechanical dimensions Figure 8: Layout recommendation

Recommendations for a strong ground connection and for reliable soldering of solder balls:

■ Use a pad layout similar to 8. Notice all tracks should go underneath the solder mask areas.

■ To keep the noise floor low in the sensitive receiver path of the chip, a low ohmic and low inductive connection to the supply ground is needed. 8 suggests a recommended grounding of the chip (if a ground plane is not feasible):Feed all grounds into a central viahole with a drill diameter 0.5 - 0.60mm.

■ Do not connect to any pins inside of the opening of the solder mask.

■ Open vias underneath the chip must be covered with a solderstop lid, to prevent ascending solder during the soldering process.

■ If the conductors are with a Ni-Au surface finish, then the preferred landing pad design for the solder balls covers the round landing pad with a gold surface finish as a solderable area only.

Design precautions: EMC shielding

The sensitivity of the sensor area is very high in order to achieve a long operational range of the range-finder. Thus the epc600 device is very sensitive to EMI. Special care should be taken to keep the chip away from the IR LED signal tracks and other sources which may in -duce unwanted signals. It is strongly recommended to cover the device and all passive components around the chip with a metal shield (refer to 9). The shield should be well connected to the GND on the PCB board. A hole in the front is the opening window for the sensor area. The corresponding backside area of the PCB shall be a polygon, connected to GND to shield the circuit from the backside as well.

Figure 9: EMC shield example

Ambient Light (Backlight)

A DC or AC photo-signal can be generated by ambient light, e.g. sunlight, or by cross-talk from the IR-LEDs. Refer to chapter 1.3.3: Ambi-ent-light suppression. However, if this is above the stated maximum value, then the sensor or the input electronics are saturated. This blocks the detection of the AC modulation signal.

Reflow Solder ProfileFor infrared or conventional soldering, the solder profile has to follow the recommendations of IPC/JEDEC J-STD020C (revision C and later) for PB-free assembly. The peak soldering temperature (T L) should not exceed +260°C for a maximum of 4 sec.

Packaging Information (all measures in mm)



Tape & Reel Information

The devices are packaged into embossed tapes for automatic placement systems. The tape is wound on 178mm (7inch) or 330mm (13inch) reels and individually packaged for shipment. General tape-and-reel specification data are available in a separate data sheet and indicate the tape size for various package types. Further tape-and-reel specifications can be found in the Electronic Industries Association EIA-Standard 481-1, 481-2, 481-3.

LST 27.07.2011

Page 1

File: This document is confidential and protected by law and international trades. It must not be shown to any third party nor be copied in any form without our written permission.

Raster 2.5mm2.5mm

4mm

8m

m

Pin 1 / Solder balls bottom side

Figure 10: Tape dimensions

epc does not guarantee that there are no empty cavities in the tape. Thus, the pick-and-place machine should check the presence of a chip during picking.

Ordering informationOrder number: epc600-CSP24

Package: All types are with CSP24 housing.

Packaging method: Delivery in tape on reel.

RoHS compliance: All types are compliant with EN RoHS regulations.



Functional DescriptionThis manual is arranged in following sections:

■ OperationThis general description of the operation and the functionalities is based on the user and application level.

■ Hardware DesignAll informations regarding hardware design aspects are covered here.

■ Instruction SetContains detailed description of the data communication and the command set.

■ Optic DesignThe chapter where the user finds some design guidelines for developing appropriate optics and illumination for the device.

1. Operation1.1. Introduction

The epc600 chip is based on the 3D-TOF principle. Modulated light is sent out by a transmitter. This light is reflected by the object to be detected. The returning light is sampled by a photosensitive sensor. The receiver compares the phase difference between the emitted and the received light and computes the time difference of the “time-of-flight”. This value multiplied by the speed of light (ca. 300'000km/sec) and divided by 2 corresponds directly to the distance.

epc600device Backscattered light with a time delay

dependent on the distance between the object and the device

Object

Figure 11: The time-of-flight principle

1.2. General overview

The epc600 chip is designed to enable simple and cost effective system designs. Together with a tiny microprocessor e.g. PIC 10F206 and few external components, a very low cost but fully functional TOF sensor system can be built (refer to 12).

The epc600 system-on-chip contains:■ A full data acquisition path with a power driver for the LED, the photo-receiver, the signal conditioning, the A/D converter and the signal

processing.■ An on-chip controller managing the data acquisition and the data communication.

■ A 2-wire serial interface for the command and data communication.

■ A supply-voltage power management unit.

Microprocessore.g. PIC10F206

IR LED

epc600-pic

LED

LEDF

SCLK

SDATA

< 180mACCDSCLK

SDATA

2-wire interface

OUTDIST

Figure 12: Basic application

The measurement functionality supports distance and ambient light measurement with variable integration times, on-chip temperature measurement and LED current feedback for drift compensation.

The sensitivity of the receiver can be adjusted on the fly to the object reflectivity, the object distance and the ambient light conditions by means of integration time. The longer the integration time, the higher the sensitivity.In cases where the illumination power of the built-in driver is not sufficient, the epc600 chip can also be used with an external LED driver. This allows longer operational ranges or faster measurements, resulting in a faster response time and reduced ambient light sensitivity.



1.3. Operational mode

This chapter lists the available features for the epc600-device.

The range-finder works in combination with a tiny microprocessor. It operates according to a single shot principle. A command sent by the microprocessor sets the user parameters in the chip and stimulates the measurement. The device executes the requested task standalone and sends back the answer (data) according to 13.

Measurement n

Response:Read data

measurement cycle time tCYCLE

Calculation n-1Distances & Quality

Measurement n-1

Measurement n

Measure n

Measure n-1 Measure n+1

Calculation nDistances & Quality

Command:Set parametersTrigger capture



Response:Read data

Response:Read data

measurement time tMEAScommunication time tCOM

Figure 13: Basic distance measurement

The microprocessor controls the parameter settings for the measurement and the start. It computes from the read-out data the final dis-tance, quality, ambient-light and temperature data. This also includes applying the necessary correction algorithms and to adapt the epc600 settings to the useful operational range and present scenery conditions.

The epc600 chip supports range finding as a single spot distance measurement, ambient-light measurement (similar to a Luxmeter) and temperature metering.

1.3.1. Distance measurement

The distance measurement is done by single shots following the protocol in 14, first section.

Request measurement:- Select type- Select integration time- Send command

Wait for response

Read measurement data

Set measurement typeSet integration time

Do measurement

Send data

Idle

IdleCalculate result

Request data:- Send command Tx

Wait for response

Read data

Fetch data

Send data

Rx

Idle

Idle

epc600Microprocessor 2-wire interface

Tx

Rx

Figure 14: 2-wire communication sequences Measurement and data reading



A command, including the measurement type and integration time, sent by the microprocessor to the 2-wire interface, sets the epc600-chip configuration and triggers the measurement. The device operates standalone to perform the distance measurement. When it is finished, the chip responds by sending the results: a distance and quality value. Based on this data, the microprocessor computes the final mea-surement result in regards to the necessary correction factors e.g. offset, ambient-light, and temperature drift. The actual result must be read first before starting the next capture cycle. The detailed method of communication and the instruction set are described in chapter 3: Instruction Set.

The epc600 range-finder uses the time-of-flight principle. It is implemented with a repeating, continuous-mode modulation signal during the measurement phase (refer to 15). Consequently, only signals returning within the maximum time slots can be detected unambiguously. This corresponds for the epc600 to a maximum operating range of 15m. Strongly reflected signals outside of this range may therefore in -terfere with the measurement.

1.3.2. Sensitivity, integration time and operating range

The operational range of the complete system is limited by the sensitivity of the receiver as well as by the illumination power emitted by the modulating light source (e.g. LED).

Integration time t INT

Time

Ambient-light DC SDC

Modulated light SAC-PP(peak-to-peak)

LightIntensity

Figure 15: The light detected by the receiver

The system sensitivity consists of two factors: The hardware sensitivity SAC of the photo-sensor (refer to chapter:Timing and optical Char-acteristics) and the exposure time (integration time t INT).

The measurement evaluation is done by computing the distance out of 4 samples caught in one measurement cycle tMEAS. A sample is the collected power of the receiving light signal during the integration time (refer to SAC in 15). This means the sensitivity corresponds to the in-tegration time: The longer the integration time, the more sensitive the measurement.

The formula for the sensitivity is a function of the integration time and is calculated from the references S AC-REF and tINT-REF in the chapter “Timing and optical Characteristics“:

SAC =t INT-REF

t INT

⋅SAC-REF

SAC is the the sensitivity corresponding to the used integration time t INT.

Illumination power, remission of the object (reflectivity), sensitivity of the sensor together with the integration time are limiting the distance operating range. For more detailed information, refer to epc's application note: AN02 Reflected power calculation.

It will probably not be possible to cover the full operational range within one integration time step due to the dynamic range of the re-ceiver's electronics. The possibilities to extend the operating range or to influence the reaction time are:

■ to adapt the integration time correspondingly to the necessary sensitivity as demonstrated in 16.

■ or alternatively: use an additional, external LED driver to adjust the illumination to the needed sensitivity level (refer to chapter1.3.8: Extended operating range).

The easiest way is to adapt the exposure time to the current illumination situation (e.g. in 16). With the command formats, which allows ad-justing of the exposure time, it is easy to do. It is simple to change the exposure time on the fly, because every capture is initiated by a command sent to the chip.



rangen-1

operationalrange

n

rangen+1

rangen+2

rangen-2

Distance R

Exposure time (Integration time)

R0

2√2

R0

2

R0

√2R0 R0⋅√2 R0⋅2

2⋅T0

T0

0.5⋅T0

0.25⋅T0

4⋅T0

Figure 16: Operating ranges as a function of distance and exposure timebased on doubling the light power to the sensor

1.3.3. Ambient-light suppression

An important function of the range-finder is the ability to separate the self emitted and reflected modulated light S AC from the ambient illumi-nation SDC. The ambient-light suppression SDC allows suppression of the DC or low frequent signal distortions caused by foreign light sources e.g. sunlight, daylight, room illumination, etc. Refer to 3 for example values as a function of the wavelength and compared to sun-light.

Similar to the sensitivity is the ambient-light suppression as a function of the integration time. The longer the integration time, the more the measurement is sensitive to the ambient-light.

SDC is the the ambient-light corresponding to the used integration time t INT, based on the references SDC-REF and tINT-REF of the chapter “Tim-ing and optical Characteristics“:

SDC =t INT-REF

t INT

⋅SDC-REF

1.3.4. Quality of the measurement result

The epc600 provides, in the read-out data, information on the quality of the received optical signal. It reflects the confidence level of the measurement result. The better the received signal, the better and more precise the distance measurement will be.

Each distance measurement has a corresponding quality rating, which is read as one data word together with the distance data. This 4 bit quality indicator helps to interpret the validity of the measured data.

5 lists the possible combinations for the quality values, gives an interpretation of the data and advises how to react to the situation:■ Generally: The higher the quality value, the better the quality level of the received signal, the better the accuracy of the reading and the

lower the noise. ■ The best operating level is 10.

The illumination is in a comfortable range and not too close to any limitations. The signal amplitude is inside the range 20% - 200% to the best working point for the illumination and integration time.

■ Numbers above indicate a too high illumination in the scenery. A reduction of the integration time for the next measurement is suggested.

■ Lower numbers indicate a low or too low intensity of the reflected, modulated light.A increase of the integration time (or illumination) is suggested.

■ Quality level = 0 and distance value = maximum signal:There is no usable receiver signal or a lack of signal. Possible reasons are:Regular operation: Absence of an object in the operating range.Fault conditions: - Object has too little remission (reflectivity).

- It is too far away.- There is too much ambient-light. Measure and check the ambient-light level.- The illumination is too dim. Too little modulation signal is emitted.

■ Quality level 15 or Quality level = 0 and Distance value = minimum signal:Suggests there is an object, but it is out of the usable operating range.Fault conditions: - The object has a too high remission (reflectivity).

- It is too close to the sensor.- There is too bright illumination or too much modulation signal is emitted.



■ All other quality levels:These levels indicates that the epc600 chip has detected undefined conditions during the measurement sequence caused by, e.g. a moving object. The correctness of the result is questionable and a repeat of the measurement is suggested.

Quality value Measurement result Illumination What to do?

Object Accuracy

Quality value = 0 and Distance value = 3'000d

no --- no signalRepeat measurement

with an increased integration time

1 detected bad too low (<7%)Repeat measurement

with an increased integration time

2 detected reduced low (7 – 20%)Measured value okay.

For the next measurement, use an increased integration time

10 detected good good (20 – 200%)Measured value okay.

For the next measurement, use the same integration time

Quality value = 15 or

detected signal saturation too high (>200%)Repeat measurement

with a decreased integration timeQuality value = 0 and Distance value = 0d

others --- --- undefined conditions Repeat measurement

Table 5: Quality levels

1.3.5. Ambient-light measurement (“Luxmeter”)

Instead of reading distance data, the epc600 chip can measure the ambient-light level. Functions of this feature are:■ Use to compensate deviations in the distance measurement caused by the presence of ambient light.

■ Monitor the ambient-light level during the distance measurement to prevent faulty conditions.

■ Use the ecp600 as a “Luxmeter” e.g. for brightness control.

■ or in combination e.g. where the presence or absence of an object in the environmental illumination needs to be controlled.

1.3.6. Temperature metering

An on-chip temperature sensor gives back temperature readings. This allows for the compensation of the signal drifts caused by changing thermal conditions in the light source and the sensor. The data access follows the protocol in 14, second section. For the calculation of the value, refer to 3.2.4: Response: Temperature.

1.3.7. Calibration and compensations

Due to the fact that the range-finder chip does not know its surrounding environment and the phase-shifts caused by the electronic imple-mentation and also due to manufacturing tolerances, a calibration of the sensor is necessary.

Whereas a simple light barrier doesn't need the same accuracy as a range-finder, the compensation and and calibration is dependent on the application.

Influencing variables for various attributes are:

■ Distance: Offset, Slope scaling, Linearity, Reflectivity, Ambient-light, Integration time, Temperature.

■ Reflectivity of the object: Quality, Ambient-light.

■ Ambient-light: Offset, Slope scaling, Linearity, Integration time, Temperature.

■ Temperature: Offset, Slope scaling, Linearity.

These compensations are necessary for the microprocessor to correct the raw distance data in the final measurement.

1.3.8. Extended operating range

The epc600 is a range-finder designed as a system-on-chip for minimum part count circuits. Therefore, a LED driver is integrated on-chip.

In cases where the illumination, achieved with the built-in driver, is not sufficient to detect near and far objects in the expected operational range or in the necessary reaction time, the epc600 chip can be used with a more powerful external LED driver (refer to chapter 2.4 Exter-nal LED driver).

1.3.9. Measurement sequence

A basic possible measurement flow is given in 17:■ Execute a distance measurement and check the quality of the signals. If action is needed, do it accordingly.

■ If the camera operates in thermally changing conditions, from time to time read the temperature for compensation.

■ Calculate, based on the correction data, the final distance value – or whatever is needed.

■ Optional: After START or if needed, check the ambient-light level to evaluate the maximum proper exposure time (or if possible, set the correct modulated illumination power compared to environmental condition).



MEASUREMENTdistance

Quality = 1 or(Quality = 0 and

Distance = 3000d)

Quality = 15 or(Quality = 0 andDistance = 0d)

quality?

Quality = 2 or 10

quality?

Quality <> 0, 1, 2, 10, 15

all other

READtemperature

Calculatetemperature

Calculatedistance

continue?

no

yes

quality?

Quality = 2

Quality = 10

increaseintegration time

ENDmeasurement

decreaseintegration time

STARTmeasurement

Figure 17: Principle measurement flow

This flow is not only for detecting objects. It is also possible to observe and track the object (once captured).

1.3.10. Multi range-finder application

Light barriers are not always operating in a single sensor application. In some applications, more than one sensor is deployed to partially or entirely cover the same observation field. The epc600 range-finder uses signal-processing based on the sinus modulation theory of the time-of-flight principle.The LEDs are modulated with 10MHz square-wave and a duty cycle of 1:1. There is no coding in the modulation sig-nal to make each device unique. To date, in multi range-finder applications, cross-talk between the signals of closely placed individual sen-sors can occur.



2. Hardware Design2.1. General Hardware Configuration

The general hardware configuration section covers all design aspects for an epc600 circuit.

2.2. Power Supply, Clock and Mode setting

The external voltage supplies are +8.5V DC as a main supply and -3.0V DC as a bias voltage. Both supplies need to be well regulated and with a low level of noise and ripple voltage, because the epc600 chip is a sensitive, highly amplifying device.

All other necessary voltages are generated on-chip. The internally generated voltage levels VSC (see 4) have to be taken into consideration in order to choose the right components for the design.

All necessary power supply decouplings and the supply of the external reference clock have to be designed according to 18 and 6. Capaci-tors C3 – C8 are used for decoupling of the internally generated voltages.

Schottky diode D1 is vital to ensure a correct power-up of the device.

C3

LED

NC3

LEDF

VREF

VDDIO

VDDHPX

VDDPX

VDDCP

VDDBS

XTAL1

XTAL2

GNDM

VDDT

SDATA

SCLK

NC2

NC1

VDDPLL

VDDCORE

GNDLEDGNDPLLGNDAGND

VDD

epc600

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21 22 2324

C6

C8

C4

C5

C7

C9

+

C2

C1

VDD +8.5V

GND

D1

C10

C11

Y1

VDDBS -3.0V

Figure 18: Main power supply decoupling and clock supply

Part No. Pin Pin No. Component value

Min. Nom. Max. VSC Type

C1 VDD 10 10μF +8.5V

C2 VDD 10 1μF +8.5V Ceramic X7R

C3 VDDCORE 2 1μF 1μF 3.3μF +1.8V Ceramic X7R

C4 VDDPLL 17 1μF 1μF 3.3μF +1.8V Ceramic X7R

C5 VDDIO 7 3.3μF 3.3μF 10μF +5V Ceramic X7R

C6 VDDPX 8 3.3μF 3.3μF 10μF +5V Ceramic X7R

C7 VDDPXH 9 3.3μF 3.3μF 6.8μF +10V Ceramic X7R

C8 VDDCP 11 10nF 100nF 100nF +12V Ceramic X7R

C9 VDDBS 6 10nF 10nF 20nF -3V Ceramic X7R

C10 XTAL1 15 27pF +1.8V Ceramic X7R

C11 XTAL2 16 27pF +1.8V Ceramic X7R

Y1 XTAL1 & XTAL2 15 & 16 4 MHz Crystal-oscillator

D1 VDD & VDDCP 10 & 11 Schottky diode

Table 6: Component values

Leave open pins NC1, NC2, NC3 and VREF. They don't require any termination.



2.3. On-chip LED driver

A feature for the minimum part count system is the on-chip LED driver. 19 & 20 show examples for possible circuitries. The design has to take in consideration that these LEDs are switched very fast (10MHz) and with high power (<180mA). Suggested are high speed LEDs with short switching times e.g. Stanley DNK5306, Osram SFH4059, Vishay VMB2000. The layout needs to be well decoupled and with low Z conductors.

Note: Take care that the voltages at LED and LEDF do not exceed their specified operational range of maximum +5V.

Short range application design

The circuit in 19 drives two power IR LEDs. The LED output LED is driven by an open source switching transistor. The illumination intensity of the LEDs is defined by the current flowing through the resistors R1. For output LED = on, the current of resistor R1 is <180mA. In order to have safe voltage operating conditions for output LED and input LEDF, there is a minimum current of <1mA flowing through the LED diodes in the off-state. This also gives the advantage of enhanced switching performance for the LEDs. This off-current is set by the resis-tor R2. The LEDF feedback input is used by the ep600 to adjust the signal correlation for the delay to the real phase conditions of the LEDs, influenced by the design, temperature and aging. C3 and C4 are the charge capacitors to supply the LEDs. In order to support the required fast switching, C3 shall be of a ceramic type. The decoupling of the supply of the epc600 is done by C1 and C2 (ceramic type). The resistor R3 decouples the LED feeding circuit from the ep600 supply. Whereas the voltage drop of the diodes D1A and D1B adjust the voltage supply level to the LED supply level. The advantage of this concept is that it gives a good decoupling between the epc600- and the LED-supply.

For the LED power dissipation calculation, refer to chapter 3.3.6: Cycle times & reaction time.

epc600

LEDF

LED

GND

VDD

GND

VDD = 8.5V

LED1SFH4059

LED2SFH4059

R24k7

R122R

C3100nF

+C110μF

GND

C2100nF

+

C410μF

R315R D1A

BAV99

D1BBAV99

Low Z, fast switching connection

GNDLED

epc600

LEDF

LED

GND

VDD

GND

VDD = 8.5V

LED1SFH4059

LED2SFH4059

LED3SFH4059

R34k7

R418R

C3100nF

+C110μF

GND

C2100nF


GNDLED

Figure 19: Short range application with decoupled LED supply

Figure 20: Mid range application with minimum part count circuit

Mid range application design

The circuit of 20 is a minimum part count design for a more powerful illumination (3 LEDs are equal to 50% more illumination energy).

The design considerations are exactly the same as before. The difference is the additional third LED3, which replaces the diodes D1A and D1B, in order to have more powerful illumination. As it is used as a minimum part count design, the decoupling between the LED supply circuit and the epc600 supply is not of the same quality as in the short range example before. Therefore, the layout design regarding the noise and ripple voltage has to be done very carefully.

2.4. External LED driver

For a more powerful, sensitive or fast system application with an epc610 chip, the use of an external LED driver is an option. The design has to take into consideration that the LEDs are modulated at high frequencies (10MHz) and with high power. So far, the layout needs to be well decoupled and with low Z conductors. The schematic has to follow the correct signal inversions as given in 21. This is important in order to have the correct phase for the feedback signal at input LEDF.

Note: The voltages at LED and LEDF must not exceed their specified operational range.

epc600 LED's output LED pin is driven by an open source switching transistor. The pull-up termination resistor R1 to the V_LOGIC supply guarantees safe voltage operating conditions for the output LED. The modulation signal of output LED feeds a fast inverting digital buffer IC1. It drives the fast switching transistor T3. T3 switches the current through LED-1LEDn on/off to modulate the light. Output LED = low corresponds to light = on. The voltage divider R7+R8 attenuates the modulation signal to the correct maximum voltage and input-swing level for the phase feedback to the input LEDF.

As opposed to the on-chip driver, such a design can have additional light levels as the circuit in 21 shows. A I/O port of the microprocessor switches the intensity to the LOW or HIGH level. The illumination (current through LED1-LEDn) is controlled by R5 for the low (LED LOW), and with the sum of the currents through R4 and R5 for the bright (LED HIGH) illumination level. The level-shifter T1, R2, R3 brings the control signal from I/O port to the switch T2. I/O port = low corresponds to level LED LOW.



T3IC1

R6

R7

R1

LED1

LEDn

R2

T1

T2

R5R4

R3

+C2 C3

epc600

LEDF

LED

GND

VDD

GND

C2100nF

VDD +8.5V

V_LOGIC

GND_LED

V_LED

GND_LOGIC

GND_LOGIC


Microprocessor

SCLK

SDATA

SCLK

SDATA

2-wire interface

LOW / HIGH

GNDLED

Figure 21: Long range or fast response application

Advantages of this circuit are the free design of the illumination power (number of LEDs), additional selectable light levels for extending the operation range, the independent voltage supply for the LEDs and the strong decoupling of the epc600 supply and LED circuitry.

What performance can be achieved?

A typical example of an application is a very small, single spot distance gauge (refer to 23). In this example, a range of up to 4m can be expected on white targets when using two SFH4059 LEDs directly driven by the LED pin with a collimator lens of 17mm focal length, a receiver lens of approx. 15x15mm with a focal length of 17 mm using an integration time t int of 410µs.

The response time in this application is t resp. = 4 * tint + 255µs = 1.859ms.

LED1

NC3

LEDF

VREF

VDDIO

VDDHPX

VDDPX

VDDCP

VDDBS

XTAL1

XTAL2

VDDT

GNDM

SDATA

SCLK

NC2

NC1

VDDPLL

VDDCORE

GNDLEDGNDPLLGNDAGND

VDD

epc600

1

2

3

4

5

6

7

8

9

10

11

12

13

14

17

18

19

20

21 22 2324

VDD +8.5V

D1BAS40

C9

C8

C7

C6

C5

C4

C3

10n

100n

1μ

3μ3

3μ3

3μ3

1μ

LED1SFH4059

LED2SFH4059

R24k7

R118R

C12100n

GND Low Z, fast switching connection (as short and wide conductors as possible)

15

16

C1127p

C1027p

Y14MHz

C21μ

C110μ

GND

SDATA

SCLK

+

D1ABAV99

D1BBAV99

VDDBS -3.0V

Figure 22: Minimum part count application



epc600 chipwith IR filter on topIllumination LEDs

Figure 23: Low power, high performance distance gauge. Figure 24: Chip on PCB board

2.5. 2-wire interface

All data communication to and from the epc600 chip goes over the two lines SDATA and SCLK of the 2-wire serial interface (refer to 25).

LED

NC3

LEDF

VREF

VDDIO

VDDHPX

VDDPX

VDDCP

VDDBS

XTAL1

XTAL2

GNDM

VDDT

SDATA

SCLK

NC2

NC1

VDDPLL

VDDCORE

GNDLEDGNDPLLGNDAGND

VDD

epc600

GND

VDD

Microprocessore.g. PIC 10F206

VDD +8.5V

GNDGND

+5.0V

I/O1

I/O22-wire interface

R1(optional)

+5.0V

Figure 25: 2-wire interface wiring

SCLK line

SCLK is the serial clock signal. It is unidirectional and always driven by the microprocessor.

The maximum 'HIGH' pulse length is not defined. The maximum 'LOW' pulse length must be < 1ms.

ERROR handling: A 'LOW' pulse > 1ms will reset the epc600 chip.

SDATA line

SDATA is the serial data line. It is used in a bidirectional way. Depending on the communication direction, it is either driven by the micro-processor or the epc600 chip (refer to 25). A “wired-OR” compatible I/O circuitry on either side is used to handle unexpected error situa-tions. It avoids permanent damage of each party in case they drive opposite logic values.

The microprocessor can achieve the Wired-OR connection by using programmable open-drain I/O pads, or writing a permanent logic low to the output and switching the line between the high-Z and transparent modes. A pull-up resistor to +5.0V will terminate the line to logic high during the high-Z state. By default, the epc600 device enables an internal pull-up resistor to +5.0V on the SDATA pin. If the rise time of the SDATA line is not steep enough, the user may either enable an embedded pull-up resistor in the microprocessor or add an external one (R1) in parallel.

ERROR handling: If the epc600 device detects a communication error, it will pull the SDATA line permanently to low until the interface will be reset.



3. Instruction SetThe 2-wire serial interface allows the user to communicate with the epc600 chip. The description of the hardware is in chapter 2.5: 2-wireinterface. The graph of the principle communication flow is in 14.

Starting a measurement, reading the result and setting the correct user parameters for operation are the main functions. All configurations are set at run-time, are loaded immediately and are not stored in the chip.

3.1. 2-wire serial interface

The interface is for single slave use. It is targeted to operate up to a 10MHz clock frequency. Only 2 wires, one bidirectional data transmis -sion and a clock line, are needed. This allows the use of a tiny microprocessor as a controller for the chip. Based on a handshake protocol the chip is either receiving or transmitting data during active clock cycles. The general waveform definition and timing are listed in 26 and 7.

In the idle state, the SCLK and SDATA lines are in the high state (outputs in tristate mode terminated with a pull-up resistor). The transmis-sion is always initiated with a start bit on the SDATA line: SDATA = low. This forces the microprocessor to clock the SCLK line with the nec -essary number of cycles for sending or reading the data. The falling edge of the clock puts the data to the SDATA line. At the time of the rising edge, the data is valid and readable. After the last rising clock edge the sender unlocks the SDATA line and both lines remain in the high state.

tDR

tDH

tH

CLK1 CLK2 CLKnSCLK

SDATA

trfSCLK

trfSCLK

tL

tSCKL

MSB LSBS

tS

tLSBH

Sender pulls SDATA to low:Hand-shake signal for WRITE

Sender changes mode:from WRITE to IDLE

Idle Sender writes to SDATA Idle

IDLE IDLE

≈≈

≈

Figure 26: General waveforms for 2-wire transmission (telegram)


SCLK 2-wire serial clock

SDATA Serial data, bidirectional transmission

tSCLK Cycle time of SCLK 100 ns

tH High period of SCLK 50 ns

tL Low period of SCLK (refer to ERROR handling) 50ns 1.0ms

trfSCLK Rise or fall time of SCLK (20% - 80% of signal amplitude) 10 ns

tS First negative SCLK edge after negative edge of SDATA 100 ns

tDR Data ready before positive SCLK edge 50 ns

tDH Data hold after positive SCLK edge 0 ns

tLSBH Data hold after positive SCLK edge of last bit transmitted (LSB) 0 ns

Table 7: General timing 2-wire transmission

3.2. Commands & responses

The epc600 device works on a task principle: The chip is in a idle state and performs a single measurement or a read-out on command only (refer to 14).

The microprocessor sends a command to the chip. It is processed immediately. The tasks are: Execute a measurement or read data. When the processing of the instruction is finished, then the chip sends back the answer to the controller by default. Refer to 13 and 14.

The command format always has 8 bits, including 4 bits for command itself (C0-C3) and 4 bits to set the integration length (I0-I3). Bit 7 (MSB) is transmitted first, bit 0 (LSB) last.

The response format is always 16 bits. Bit 15 (MSB) is transmitted first, bit 0 (LSB) last.



3.2.1. Command: Commands & Integration times

Name: Command & Integration time

Bit 7 6 5 4 3 2 1 0

C3 C2 C1 C0 I3 I2 I1 I0

Description CMD [3:0] INT [3:0]

CMD: Command to start the measurement with a defined integration time or to read data.

Description CMD INT epc600 response Waiting time

Read temperature 0101 0000 Temperature tACC = 1.5 μs

Measurement of distance and quality 1000 see INT Distance & quality tMEAS

Measurement of ambient-light level 1101 see INT Ambient-light level tMEAS

Don't use OthersINT: Sets the integration time for the measurement. The measurement time is tMEAS = 4x integration time + 255 μs.

Note: A doubling of the integration time is equal to a doubling of the illumination in the scenery.The integration times below in the table are for a LED modulation frequency of 10MHz.

Time INT Time INT Time INT Time INT

1.60 μs 0000 25.6 μs 0100 408 μs 1000 6.56 ms 1100

3.20 μs 0001 51.2 μs 0101 818 μs 1001 13.2 ms 1101

6.40 μs 0010 103 μs 0110 1.64 ms 1010 26.3 ms 1110

12.8 μs 0011 205 μs 0111 3.28 ms 1011 52.5 ms 1111

3.2.2. Response: Distance & Quality

Name: Distance & Quality

Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Q3 Q2 Q1 Q0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

Description QUAL [3:0] DIST [11:0]

QUAL: Quality value. Generally the higher the value, the better the quality level of the received signal, the better the accuracy of the reading and the lower the noise. The best operating level is 10. Here, the illumination is in a comfortable range and not close to any limitations. A detailed description is in chapter 1.3.4: Quality of the measurement result .

DIST: Distance value, without corrections (@ 10MHz LED modulation frequency).1 LSB = 0.5 cm. Minimum DIST = 0d ≙ 0m. Maximum DIST = 3'000d ≙ 15m.Note: Distance values are valid as long as Quality value >0.

The basic calculation formula is D [cm] = DIST [11:0]⋅1500cm3000

⋅DCORR⋅+ DOFFSET

D Adjusted distance in centimeters

DCORR Scaling of the slope

DOFFSET Offset compensation

DCORR and DOFFSET need to be evaluated by a calibration of the sensor. Refer also to chapter Calibration and compensations.



3.2.3. Response: Ambient-light level

Name: Ambient-light level

Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Q1 Q0 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

Description 0 0 AMBIENT [13:0]

AMBIENT: Ambient-light value (“Luxmeter”). Output range: signed (0d – 8188d)

The basic calculation formula is SDC =ABS (AMBIENT [13:0])

4⋅SDC-CORR⋅+ SDC-OFFSET

SDC Scaled value of ambient-light level

SDC-CORR Scaling of the slope (necessary only for high accuracy measurements)

SDC-OFFSET Offset compensation (necessary only for high accuracy measurements)

SDC-CORR and SDC-OFFSET need to be evaluated by calibration of the sensor.

3.2.4. Response: Temperature

Name: Temperature

Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Q3 Q2 Q1 Q0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

Description 0 0 0 0 TEMP [11:0]

TEMP: Temperature value.

The basic calculation formula isTemp [deg C] =

(TEMP [11:0]⋅ 40002048)− 2100

7.2

Temp Scaled value of the temperature in degrees Celsius.

For high accuracy measurements, exact correction factors need to be evaluated by a calibration of the sensor.

3.3. Communication tasks

3.3.1. Measurement sequence (Distance or ambient-light)

27 shows the communication during a measurement sequence:■ The microprocessor initiates the communication with a start bit on the SDATA line followed by actively clocking the line SCLK and the

command transmission.■ After completion of the command the epc600 chip is starting the measurement. Meanwhile, the microprocessor waits for a response.

■ The epc600 chip sets the start bit on SDATA when the measurement is executed and the data are ready ( tMEAS).

■ Now the microprocessor can read out the the data by active clocking.

3.3.2. Read sequence (Temperature)

The sequence is identical to the above except for the waiting time of the response of the chip ( tACC).28 shows the communication during a read sequence:■ The microprocessor initiates the communication with a start bit on the SDATA line followed by actively clocking the line SCLK and the

command transmission.■ After completion of the command, the epc600 chip fetches the data. Meanwhile, the microprocessor waits for a response.

■ The epc600 chip sets the start bit on SDATA when the data are ready ( tACC).

■ Now the microprocessor can read out the the data by active clocking.

3.3.3. Error detection by the microprocessor

Before the microprocessor tries to set a start bit, it first checks the SDATA line according to 29. SDATA = low indicates an ERROR. This means that the epc600 chip signals an error status or the interface is faulty.

3.3.4. Reset sequence

Whenever necessary, the microprocessor can reset the epc600 chip . The reasons for the reset are either due to an error detection during the transmission or in order to resynchronizing the interface. The epc600 interprets a low signal > 1ms on the SCLK line as a reset com -mand for the chip (29). After reset, the communication has to restart.



SCLK

SDATA C2 C1 C0 I3 I2 I1 I0 Q3 Q2 Q1 Q0 D11 D10 D1 D0

LSB

C3

MSB MSB LSB

uP polls SDATAepc600: idle

Idle

epc600 pulls SDATA to low as soon measurement is finished:Data ready hand-shake signal to uP

tMEAS

SS

Response: epc600 writes SDATA uP reads SDATA

Command: uP writes SDATA epc600 reads SDATA

uP checks SDATA:high = continue; low = error

uP pulls SDATA to low:Command hand-shake signal to epc600

epc600 measures

Idle

≈≈ ≈

≈≈

Figure 27: Measurement sequence

SCLK

SDATA C2 C1 C0 I3 I2 I1 I0 Q3 Q2 Q1 Q0 D11 D10 D1 D0

LSB

C3

MSB MSB LSB


Response: epc600 writes SDATA uP reads SDATA

Command: uP writes SDATA epc600 reads SDATAIdle Idle


epc600 pulls SDATA to low as soon data are ready:Data ready hand-shake signal to uP

tACC

SS


≈≈ ≈

≈≈

Figure 28: Read sequence

SCLK

SDATA C2 C1C3

MSB

Command: uP writes SDATA epc600 reads SDATAIdle

uP checks SDATA:detects error

S


≈


Reset by uP Idle

tRST

tREC

normal operation ...

Figure 29: Error detection by the uP and the reset sequence

SCLK

SDATA

Response: epc600 write cycle uP reads SDATA

Command: uP write cycle epc600 reads SDATA

MSB

Command: uP write cycle epc600 reads SDATAError



≈

≈


Reset by uP Idle

normal operation ...≈≈

≈

≈≈≈

a) epc600 detects error: writes low to SDATA

MSBMSB LSB LSB

SCLK

SDATA

MSB

Error



≈

≈


Reset by uP Idle

normal operation ...≈≈

≈

≈≈≈

b) epc600 detects error: writes low to SDATA

MSBMSB LSB LSB


Response: epc600 write cycle uP reads SDATA


≈



S

S S

S

S

Figure 30: Error detection by epc600


tMEAS Measurement duration. Depends on the selected integration time 1.60 52'427 μs

tACC Propagation delay of the epc600 after command transmission 1.5 μs

tRST Reset signal to the epc600. The time SCLK must be pulled low. 1.0 ms

tREC Recovery time after reset of epc600 4.0 ms

Table 8: Timing of the measurement, read and reset sequence



3.3.5. Error detection by the epc600 chip

The epc600 chip detects if there are more falling clock edges than necessary for the transmission (see 30). If it happens, the communica-tion is erroneous and the device puts the interface in an ERROR condition by pulling down SDATA = 0. To leave this state, the micropro-cessor has to reset the epc600 chip.

3.3.6. Cycle times & reaction time

For a common understanding, we distinguish between the cycle and the reaction times.

The following examples uses:■ 10MHz modulation frequency at the LED pin.

■ the reference integration time of 103μs from the chapter: Timing and optical Characteristics.

■ a data transmission rate of 1Mbit/s.

Integration time tINT

Integration time t INT (or exposure time) is the timeframe in which the light is sampled by the sensor (refer to chapter 3.2.1: Command: Com-mands & Integration times). It is equal the exposure time (where a shutter is open for passing the light to the sensor).

Duty cycle of the modulation signal

The ratio of on to off for light power emission of a modulated signal (e.g. 50% for a modulation duty cycle 1:1).

Measurement time tMEAS

The time the epc600 device needs to execute a measurement from the point of receiving the command until it responds.

tMEAS = 4⋅t INT + 255μ s e.g. 663μs = 4⋅102μs + 255μs

Communication time tCOM

The period from the end of the measurement until the next start in a continuous mode manner (refer to 13). It is the real communication time used by the 2-wire interface and all the additional time the microprocessor needs to send the next command to the chip.

Example: Command write: 1 check bit + 1 start bit + 8 command bits

Read response: 1 check bit + 1 start bit + 16 data bits

Data rate: 1Mbit/s

Communication time tCOM e.g. 28μs = 10⋅1μs + 18⋅1μs

Measurement cycle time tCYCLE

The measurement cycle time tCYCLE includes the duration to execute a complete measurement cycle until the next cycle propagation is pos-sible (refer to 13).

tCYCLE = tMEAS + tCOM e.g. 691μs = 663μs + 28μs

Data processing time tPROCESS

The period needed by the microprocessor for the final result: “calculation distance & quality” (refer to 13)

Reaction time tREACTION

The reaction time denotes the necessary time interval to change the distance output DIST of the microprocessor from one state to the other (refer to 12). The maximum reaction time tREACTION of the range-finder system is given by

tREACTION = 2⋅ tCYCLE + tPROCESS e.g. 1'482μ s = 2⋅691μs + 100μs

LED on-time tLED-ON and LED duty cycle

For the power dissipation estimation of the emitter LED (at pin LED), the LED on-time and the duty cycle are of importance. The following time periods have to be taken in consideration:

■ tINT : during the integration period, the LED outputs are active for 50% of the time.

■ tMEAS : there are 4 integration periods t INT per measurement cycle tMEAS.

■ tCOM : during the communication time the LED outputs are not active.

The formula for the LED on-time is: tLED−ON = 4⋅t INT

2+ 15μs e.g. 219μs = 4⋅102μs

2+ 15μ s

Duty cycle DCLED-ON for LED on-time is DCLED−ON =tLED−ON

tCYCLE

e.g. 32% = 219μs691μs



4. Optical DesignThe purpose of this section is to give some important guidelines to the optical designer to help him choose the appropriate optics design for his application.

Photosensitive area

The optical free area which has to be covered well by the illumination optics. This is the relevant surface for calculating the light sensitivity of the chip.

Signal sensitivity

The signal sensitivity is defined by the minimum and maximum detectable AC modulation signal (reflected light). It is defined by the light power (Watt/m2) in relation to:

■ the photo-sensitive area of the sensor.

■ the operating integration time t INT .

■ the operating wavelength λ.

■ the angle of interest (or reflectance of the sensor surface). Refer to 3.

It is independent of■ the modulation frequency

Ambient-light suppression

The ability to suppress DC or low-frequency modulation parts of the received light signal. It is defined by the light power (Watt/m 2) in rela-tion to:

■ the photo-sensitive area of the sensor.

■ the operating integration time t INT.

■ the operating wavelength λ.

■ the angle of interest (or reflectance of the sensor surface). Refer to 3.

Refer also to chapter 1.3.3: Ambient-light suppression.

Operating range

The maximum non-ambiguity distance is < 15m for a modulation frequency of 10MHz @ the pin LED. It is given by the modulation fre-quency and the time-of-flight.

The operating range (dynamic range) of the epc600 receiver for a certain illumination level is given by the photosensor and its electronics:■ the AC signal sensitivity for the modulated light.

■ the capability of the ambient-light suppression.

■ the level of illumination.

Depending of the optical design, these ranges do not match. The optical engineer has to plan the optical design and the light power in a way that matches the application best.

For more detailed information refer to epc's application note AN02 - Reflected power calculation.



IMPORTANT NOTICEInformation furnished by ESPROS Photonics AG (epc) is believed to be accurate and reliable. However, no responsibility is assumed for its use.

ESPROS Photonics AG and its subsidiaries (epc) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is the latest and is complete. All products are sold subject to epc’s terms and conditions of sale supplied at the time of order acknowledgment.

epc warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with epc’s standard warranty. Testing and other quality control techniques are used to the extent epc deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed.

epc assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applica-tions using epc components. To minimize the risks associated with customer products and applications, customers should provide ade-quate design and operating safeguards.

epc does not warrant or represent that any license, either express or implied, is granted under any epc patent right, copyright, mask work right, or other epc intellectual property right relating to any combination, machine, or process in which epc products or services are used. Information published by epc regarding third-party products or services does not constitute a license from epc to use such products or ser -vices or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other in-tellectual property of the third party, or a license from epc under the patents or other intellectual property of epc.

Resale of epc products or services with statements different from or beyond the parameters stated by epc for that product or service voids all express and any implied warranties for the associated epc product or service. epc is not responsible or liable for any such statements.

epc products are not authorized for use in safety-critical applications (such as life support) where a failure of the epc product would reason -ably be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically govern-ing such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of epc products in such safety-critical applications, notwithstanding any applications-related information or support that may be provided by epc. Further, Buyers must fully indemnify epc and its representatives against any damages arising out of the use of epc products in such safety-critical applications.

epc products are neither designed nor intended for use in military/aerospace applications or environments unless the epc products are specifically designated by epc as military-grade or "enhanced plastic." Only products designated by epc as military-grade meet military specifications. Buyers acknowledge and agree that any such use of epc products which epc has not designated as military-grade is solely at the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.

epc products are neither designed nor intended for use in automotive applications or environments unless the specific epc products are designated by epc as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, epc will not be responsible for any failure to meet such requirements.



Documents

General Description Features - SENSOR+TESTSymbol Parameter Min. Typ. Max. Unit tON Power-up rise time for VDD 1 10 ms tINIT Start-up time 100 ms tOFF Power drop-down time for VDD 1