INTRODUCTION TO MICROCONTROLLERSAnd all that whirrs, clicks, and beeps

INSTRUCTORS

Ms. Hinterlong Lucas Sturnfield Brian Baker Thomas Houlahan

SPONSORS

Houlahan’s Tavern and Grill

PROGRAMMING LANGUAGES

.NET, Java, C++, Python…? Assembly?

WHAT MICROS CAN DO

ELECTRONICS

Electron juggling and shuffling

(some kinds of shuffling are more impressive than others)

OUTLINE Today

Basic electronics Digital electronics

Tuesday Programming a microcontroller Start projects

Wednesday Projects

Thursday Projects

Friday Projects and presentations

BASIC ELECTRONICS

BASIC ELECTRONICS - CIRCUITS

CIRCUIT DIAGRAMS

http://www.fancon.cz/slave-flash-trigger/slave-flash-en.html

WIRE AND ELEMENTS

Some elements Elements wired together

BRANCHES AND NODES

BRANCHES AND NODES

BRANCHES AND NODES

VOLTAGE AND CURRENT

Voltage Potential energy per

unit charge Measured in Volts = Joules per Coulomb Water analog:

pressure Measured between

nodes

VOLTAGE AND CURRENT

Current Flow of electrons Measured in

Amperes (Amps)= Coulombs per

Second Water analog: flow

rate Measured through

an branch (through an element)

OHM’S LAW: V = I * R

Voltage across the element = Va – Vb

Resistor has resistance R1, measured in Ohms

Current through resistor is i_R1

Va-Vb = R1 * i_R1

POWER: P = V * I

Power used by any branch is equal to the voltage across the branch multiplied by the current through that branch

Units: Joules / Coulomb * Coulomb / Second = Joules / Second = Watts

KVL AND KCL

Kirchoff’s Voltage Law The sum of voltages around any loop equals zero

KVL AND KCL

Define a ground node to be zero volts Now, each node has a voltage

KVL AND KCL

Kirchoff’s Current Law The sum of currents entering a node equals zero (a lot like mass conservation)

BREADBOARDS

Internal connections Power rails

MULTIMETERS – MEASURING VOLTAGE Multimeter must connect to circuit differently to

measure voltage or current To measure voltage, set multimeter to Voltage setting,

and place leads in parallel with branch of interest

MULTIMETERS – MEASURING CURRENT

To measure current, set multimeter to Current setting, and place leads in series with branch of interest

SERIES AND PARALLEL RESISTANCE

DIODES AND LEDS

Water analog: Check valve – only lets current flow one way

Either ON or OFF On

Anode-cathod voltage is fixed value, no matter what current (0.7 V)

Off Current is zero, no matter what

voltage LEDs emit light when ON

LEDS AND CURRENT LIMITING RESISTORS

RECAP

Voltage is potential energy (pressure) Current is flow of electrons (flow rate) Voltage is measured between nodes, or with

respect to ground Current is measured through branches

V=IR P=IV

VOLTAGE ISN’T ALWAYS CONSTANT

Speakers are driven by a voltage signal; settings the voltage sets the position of the speaker diaphragm

SENSORS AND ANALOG OUT

Some sensors vary an output voltage; the voltage corresponds to a sensor value

Maxbotix ultrasonic sensor outputs voltage corresponding to distance

RF - RADIO

Radio uses Electromagnetic waves Voltage on antenna varies Waveform carries data

POWER: DC VS AC

Direct Current Batteries, wall warts Time-constant

voltage Current flows one

way

Alternating Current Electrical outlets Time-varying

voltage Current flows

different ways at different times

Transfers power great distances with low line loss

DC AC

AC TO DC

http://hyperphysics.phy-astr.gsu.edu

LM7805 Volage regulator - takes ~9V DC, makes 5V DC

CAPACITOR

Stores energy Resists change in voltage Electrolytic are polarized,

have stripe on minus end Capacitance is measured in

Farads (typically, micro Farads)

Ceramic capacitorElectrolytic capacitor

TRANSISTOR

Considered by many to be greatest invention of the 20th century

Transistor as amplifier (radio) Transistor as switch

DIGITAL ELECTRONICS0110100001100101011011000110110001101111001000000111011101101111011100100110110001100100

(hello world)

1 AND 0

Digital logic doesn’t use analog voltages – only ‘high’ and ‘low’ have meaning Typically 5V and 0V Sometimes 3.3V and 0V Computer processor High is 1, Low is 0

MICROCONTROLLER

Programmable Chip Same idea as PC, but

on much smaller scale

BLACK BOX

Black box does stuff to inputs to get outputs Typically don’t want to care what happens

inside black box; just need to know how to give it input, and what output to expect

BLACK BOX

Need to know where to put toast Need to know to be careful getting toast; it’s

hot Need to know that ‘ding’ means toast is done Ding is an output! Power, timer setting, lever are all inputs

COMPUTER VS MICROCONTROLLER

Inputs Keyboard Mouse Microphone

Outputs Monitor Speakers

Black box Program is written

on the computer

Inputs Voltage on pins

Outputs Voltage on pins

Black box Program is written

on a computer and downloaded to the chip

Computer Microcontroller

WHY MICROCONTROLLERS?

Low cost for a lot of processing Low power (can run on batteries)

If power is well managed, can run for years on a 9V!

Small Can communicate with PCs to do complex

processing with real world effects

BLINKY LED IN A BREADBOARD

Breadboard stuff PICS are already programmed Remember: Electrolytic caps are polarized;

stripe goes to lower voltage When you apply power, LED should blink

PCB

Haha! jk jk we have awesome pcb. Let’s solder:

Soldering irons get HOT: don’t burn yourself Tinning things: put a little solder on both pieces

that you’ll connect, THEN connect them Sockets are done you get to do caps and 7805

With sockets, we don’t apply heat to a chip. Also, if the chip gets fried, we can pull it and put a new one in

Test with Blinky LED again

INTRODUCTION TO MICROCONTROLLERS

PROGRAMMING A PICMaking machines Think

ARCHITECTURE

Memory Variables – ‘registers’ – all 1 byte big F register

Declare you own Special ones, like PORTD and TRISB

Working register – the accumulator – your ‘hands’

Instructions Processor only does ONE thing at time – moves

from one instruction to the next Each instruction has an opcode (action) and

parameters i.e., movfw PORTA

CO

NFIG

& V

AR

IAB

LES

Comments prefixed with semilcolons

Compiler info

Config bits

Constants

Variables – declared two different ways

BEG

INN

ING

OF C

OD

E

ORG declares a place in code memory

0x000 is restart

0x004 is interrupt

(ignore interrupt for now)

Now every line is a comment, label, or instruction

nop – do nothing

goto [label] – jumps to a named label

INIT

IALIZ

ATIO

N

bcf and bsf – bit modification

Special f registers and bank bits

Moving through accumulator

PORT and TRIS control pins

ADCON1 and analog

TH

E A

CTU

AL L

ED

BLIN

KIN

G C

OD

E

Turn it on

Wait using a subprocedure (goto and return)

Turn it off

Wait using sub

Loop back & main program loops

TH

E D

ELAY

SU

BP

RO

CED

UR

E

Some calculated exact cycle usage (it’s deterministic – depends on clock frequency!)

Involves looping and counting down a bunch – takes a lot less room than 5000000 nop instructions!

Note ‘return’ statement

END statement is end of our code

Branching – no IF; decfsz (also, btfss/btfsc)

ADDING A BUTTON

We have processing and output, let’s add an input

DEBOUNCING

Voltage doesn’t switch all that cleanly

Our PIC is faster than the debounce!

Solutions Hardware – add a

capacitor to filter Software – poll

button again a set time after it first changes

CODE CHANGES

TRISB bit 0 should be 1 for an input! movlw b’00000001’ movwf TRISB

Completely different loop New (shorter) delay functions (please excuse

the messy code!) We’ll have the PIC turn LED at PORTD,7 on or

off when pressed, like a lightswitch

BU

TTO

N L

OO

P

Check to see if button changes – if it does, go to double check

doubleCheck waits about 2ms and then checks button again. If not pressed, go back, if pressed, go on

setLED or clearLED depending on LED state

Then, wait for button release before checking for another button press

PROGRAMMING THE PIC

Project -> Build All (F10)

Can has Build Succeeded?

Don’t need to download each time; compiling can help you find errors

If it’s the only option: Programmer->-> Select Programmer -> PICkit 2

Then, Plug in PICkit 2 to

header Programmer->-> Program

Compile Download

DEBUGGING The PIC is a really

good black box You don’t get info out

of it unless you code it to output info!

LEDs can be useful for tracking what state the PIC is in

For more complex info, communication with a computer is the way to go

Extra credit for laughing at my visual puns!

SERIAL/COM/UART/RS232

Uses 9 pin connector Only 3 are used – Gnd, Rx, Tx

Many new computers don’t have this connector USB to Serial adapter are widely available

PIC has built in module for this (UART) Libraries for Serial Hyperterminal

SERIAL COMMUNICATION: COMPUTER SIDE

Serial ports show up as COM ports (COM1, COM2, etc)

You can write your own programs

Hyperterminal is easy to use for simple things (including debugging)

ASCII table

SERIAL COMMUNICATION: COMPUTER SIDE

Name connection Select COM Port Settings

9600 baud is commonly used

To see what you type, File -> Properties ASCII Setup… button Check ‘Echo typed

characters locally’

SERIAL COMMUNICATION: PIC SIDE

RS232 standard 1 is -12V, 0 is 12V

We usually just want or have 5V supply, not 24V split in the middle!

MAX232 handles inversion and voltage boosting

SER

IAL C

OD

E

Enabling Serial communication on the 877a is a matter of setting up the associated f-registers. SPBRG stores a value that corresponds to 9600 baud, enable bits are set, etc

Documentation for how to do this (for other modules, too) is in the 877a datasheet

SERIAL CODE To transmit, load a value

into TXREG Values for ASCII letters can

be found at asciitable.com Before transmitting again,

wait for transmit to finish with waitForTX

To receive, call waitForRX – it puts received value into w (and variable rxData) Be careful using; it stops

everything until a character is received! There are other ways to

deal with this

ALU

Arithmetic Logic Unit Handles instructions like addwf, subwf, incf,

decf, rrf, rlf, etc After performing operation, some bits in in

STATUS might change: Z, C, DC If Z is set, result was zero If C is set, carry occurred (or, for a situation

where a borrow might occur, 0 if the borrow occurred) Also stores bits that ‘fall off’ from rrf and rlf

ALU

To test if two things are equal, movfwthing1 subwf thing2, w ;make sure result is stored in w! btfss STATUS, Z goto not_equal goto equal

rrf and rlf are rotate right and rotate left through carry Always bcf or bsf STATUS, C before doing rrf or

rlf!

COMPONENTSA part bin fit for Frankenstein

THREE CATEGORIES

Inputs (Sensors)OutputsProcessing

COMMUNICATION These inputs and/or

outputs RF

Sparkfun has some modules

Bluetooth Appear as COM port on

computer Sparkfun +: Current wireless

protocol, devices for cell phones (Android!)

-: $$$ RFID

TINY circuits, powered by antennae

Not all standardized Implants Key cards

SENSORS - LIGHT

Photocells Resistance

decreases with more light

IR Receivers Communication Coupled with IR

LEDs, can do rangefinding

PIR Motion Sensing CCD Cameras

SENSORS - POTENTIOMETERS

Variable resisters Depending on

control’s position, resistance changes

Usually have a split design – 3 pins. Resistance from 1 to 2 plus that from 2 to 3 is always the same; put power at 1 and 3, and voltage at 2 varies

SENSORS - ULTRASONIC

Maxbotix makes easy to use ultrasonic rangefinders Different

sensitivities Can be daisy-

chained Analog, Serial, and

Pulse-width outputs ~$30 each

SENSORS - TEMPERATURE

Thermocouple Voltage corresponds

to temperature +: Cheap,

standardized -: Nonlinear!

Maxim OneWire Actually pretty

complicated Can set ‘alarm’ temps,

0.5 degrees C resolution

SENSORS - BUTTONS Tact switches

+ Cheap! Standardized

- Small, not pretty Keypads

+ Can look awesome - Weirder to interface

with Videogame

controllers Can wire directly to

buttons, analog sticks PS2 interface is

known

SENSORS - WIIMOTE

Communicates with Bluetooth Computer drivers

have been developed

Even better, Nunchuck uses I2C 3-axis accel, analog

stick, and two buttons for $20

PCB interface available (FunGizmos.com)

SENSORS – ACCELEROMETERS AND GYROSCOPES

There are MEMS Gyroscopes + small, interface with

electronics easily - $$$

Used together, accels & gyroscopes provide data to do position tracking There’s some drift Some serious number

crunching needs to be done to track in real time

SENSORS - GPS

+ Tons of fun data! - Ceiling interferes,

and $$$ (They DID pay to put

a bunch of satellites in orbit…) (Plus they crunch a

lot of numbers)

SENSORS – TOUCHPADS, MICE, KEYBOARDS

Lots of Multitouch interfaces

Mice & Keyboards – PS2 interface

SENSORS - OTHER

Alcohol Gas Barometric If you look hard

enough, you’ll probably find what you’re looking for

Mic & voice recognition - SAPI

Cameras & Computer Vision - OpenCV

OUTPUTS – ON/OFF Simply turning things

on and off can be an output Triacs for controlling

120V AC Working with 120V AC

is MUCH MORE DANGEROUS – never work on a live circuit

Brian used MAC15A8 triacs, and MOC3012 / NTE3047 drivers

Transistors for DC NPN goes at bottom,

PNP goes at top

OUPUTS – LEDS AND 7 SEGMENT LCDS LEDs are fun

+ Cheap! Add a coin cell battery, a

magnet, and some scotch tape, and you have an LED throwie

Developed by Graffiti Researh Lab

EL wire Electroluminescent wire Requires a special driving

inverter, but whole wire lights up

7-Segs Very commonly used,

pretty cheap Really just a bunch of LEDs Driver ICs are available:

put in a number, it displays it

OUTPUTS – CHARACTER & GRAPHIC LCDS

Character LCDs A little more

complicated, but great for displaying info The blue ones look cool

Graphic LCDs Abundant, because of

cell phones Much more complicated

to work with, but much more possibility Some dude had an AVR

micro displaying very basic 3D graphics

OUTPUTS - PROJECTORS

Pretty much necessitates a computer, but can do cool things GRL’s laser pointer

graffiti

OUTPUTS – BUZZERS, PELTIER, OTHERS… Piezoelectric buzzer

Very very common Speakers Peltier heater/cooler

Apply power one direction, and one side gets cool, the other gets hot

Apply power the other way, first side gets hot and second gets cool

Vibration Motors DC motor with off-

center weight on shaft Pneumatics & Hydraulics

Electrically controlled valves

OUTPUT – REGULAR DC MOTORS You set POWER, which

corresponds to SPEED, with a constant load

Apply power one way, and they turn that way. Apply power the other way, they turn the other way

Geared DC are often desired; without gearing, the motors have high speed but VERY low torque

Setting direction electronically requires a circuit called an H-Bridge

OUTPUT – SERVOS AND STEPPERS Servo motors

You set ANGLE Less than 360 degree

swing 3 pins: power, ground,

and analog voltage corresponding to angle (can use PWM)

Stepper motors You set POSITION Continuous rotation More complicated to

drive; must step pins in a sequence, i.e. 0001 to 0011 to 0010 to 0110 to 0100 etc

Separate driver ICs are available

PROCESSING Optoisolators EEPROM

Extra data storage Usually has I2C interface SD cards are apparently decently easy to interface with, too

Shift Registers Extra IO pins Use 2 or 3 pins on micro to control 8 pins on shift register. Daisy

chain to control 16, 24, etc… Tradeoff is speed: changing even one pin takes time to set them

all 7 Seg drivers

Give it a number, it turns on correct LEDs in 7 seg H-Bridge

Given logic inputs and power inputs, can connect a pin to + power or ground

Needed because a single transistor just connects the pin to + power or nothing (or, alternatively, ground or nothing)

PROCESSING Stepper drivers

Provide power, tell it to step one direction or the other, it handles the rest

PWM chips Provides more PWM channels

DACs and ADCs ADC common on PICs, but DAC isn’t. PWM can be used to

approximate And/Or/Not gates

Very basic logic circuits – useful in some situations to save IO pins (Chalkzilla example)

555 timers By choosing different resistors and capacitors to hook up to it,

you can set the pulse width, pulse delay, etc Op-Amps

These are a big deal All sorts of analog magic: amplification, subtraction, addition,

derivatives, integrals, isolation Beyond the scope of this. Take Electronics at IMSA!

PROJECTS