ARM HOW-TO GUIDE Interfacing I2C-7SEG with LPC2148 · PDF file13-12-2014 · Circuit Diagram to Interface I2C–7 seg with LPC2148 ... User Manual of LPC2148 Primer Board. Tutorial

ARM HOW-TO GUIDE

Interfacing I2C-7SEG

with LPC2148 ARM

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Contents at a Glance

ARM7 LPC2148 Primer Board ........................................... 3

I2C (Inter Integrated Circuit) ............................................ 3

Seven Segment Display .................................................... 4

Interfacing I2C - Seven Segment Display ........................... 4

Interfacing I2C – Seven Segment with LPC2148 ................ 6

Pin Assignment with LPC2148 .......................................... 6

Circuit Diagram to Interface I2C–7 seg with LPC2148 ........ 7

Source Code .................................................................... 7

C Program to I2C – 7 Segment Display using LPC2148 ....... 8

Testing the I2C – Seven segment with LPC2148 .............. 13

General Information ...................................................... 14



ARM7 LPC2148 Primer Board

The ARM7 LPC2148 Primer board is specifically

designed to help students to master the required skills in

the area of embedded systems. The kit is designed in such

way that all the possible features of the microcontroller will

be easily used by the students. The kit supports in system

programming (ISP) which is done through serial port.

NXP’s ARM7 (LPC2148), ARM Primer Kit is proposed to

smooth the progress of developing and debugging of

various designs encompassing of High speed 32-bit

Microcontrollers.

I2C (Inter Integrated Circuit)

The I2C (Inter-IC) bus is a bi-directional two-wire serial

bus that provides a communication link between integrated

circuits (ICs).I2C is a synchronous protocol that allows a

master device to initiate communication with a slave

device. Data is exchanged between these devices.



Seven Segment Display

A seven segment display is the most basic electronic

display device that can display digits from 0-9. The most

common configuration has an array of eight LEDs arranged

in a special pattern to display these digits. They are laid out

as a squared-off figure ‘8’. Every LED is assigned a name

from 'a' to 'h' and is identified by its name. Seven LEDs 'a' to

'g' are used to display the numerals while eighth LED 'h' is

used to display the dot/decimal.

Interfacing I2C - Seven Segment Display

Fig. 1 shows how to interface the seven segments with

microcontroller through I2C. I2C is a Master-Slave protocol.

I2C has a clock pulse along with the data. Normally, the

master device controls the clock line, SCL. This line dictates

the timing of all transfers on the I2C bus. No data will be

transferred unless the clock is manipulated. All slaves are

controlled by the same clock, SCL.



A seven segment is generally available in ten pin

package. While eight pins correspond to the eight LEDs, the

remaining two pins (at middle) are common and internally

shorted. These segments come in two configurations,

namely, Common cathode (CC) and Common anode (CA). In

CC configuration, the negative terminals of all LEDs are

connected to the common pins. The common is connected

to ground and a particular LED glows when its

corresponding pin is given high. In CA arrangement, the

common pin is given a high logic and the LED pins are given

low to display a number.

Fig. 1 Interfacing I2C - 7segment to Microcontroller



Interfacing I2C – Seven Segment with LPC2148

We now want to display a four digit number in LPC2148

Primer Board by using seven segment displays. The seven

segment display is connected with LPC2148 controller

through I2C.

In LPC2148 Primer Kit, 4 nos. of common anode seven

segment displays are controlled by I2C Enabled drivers. I2C

Lines serial clock SCL (P0.2), serial data SDA (P0.3)

connected to the I2C based 7-segment display driver. The

digit select lines are (MX1, MX2) controlled by the driver

chip. The 7-segmend display is powered from the 5V power

supply enabled by switch SW28.

Pin Assignment with LPC2148

7-S

EG D

isp

lay 7-SEG Driver LPC2148 LINES 7-SEG PWR Selection

SCL P0.2

SDA P0.3

Make switch SW28 to ‘7SEG’

label marking position

+5V

ONOFF

SW28

PWR ON/OFF

1234

8765

LCD7SEG

GLCDSM/RL



Circuit Diagram to Interface I2C–7 seg with LPC2148

Source Code

The Interfacing I2C – seven segment displays with

LPC2148 program is very simple and straight forward, that

display a four digit number in seven segment display by

using I2C.The C programs are developed in Keil software.

2_SEG22_SEG3

2_SEG0

2_SEG52_SEG4

2_SEG62_SEG7

U11

7 SEG DISP

E1 D2

CA

13

C4

DP5

B6 A7

CA

28

F9

G10

1_SEG11_SEG21_SEG3

1_SEG0

1_SEG51_SEG4

1_SEG61_SEG7

U8

7 SEG DISP

E1 D2

CA

13

C4

DP5

B6 A7

CA

28

F9

G10

U9

7 SEG DISP

E1 D2

CA

13

C4

DP5

B6 A7

CA

28

F9

G10

Q4BC847AL

23

1

1_SEG01_SEG11_SEG21_SEG3

C12 100n

U7

SAA1064

ADR1

CEXT2

P83

P74

P65

P56

P47

P38

P29

P110

MX111

VEE12

SCL24

SDA23

P1622

P1521

P1420

P1319

P1218

P1117

P1016

P915

MX214

VCC13

2_SEG72_SEG6

2_SEG42_SEG5

2_SEG22_SEG3

I2C 7-SEGMENT DISPLAY

2_SEG02_SEG1

R40

10k

R41

10k

3V3

C11

2.7nF

1_SEG41_SEG5

C36

22pf

C37

22pf

3.3V

X13

12MHz

LPC2148

U16

VSS16 V

DD

A7

VSS218

VD

D3

23

VSS325

VD

D2

43

VSS442

VR

EF

63

XT

AL1

62

XT

AL2

61

VSSA59

VD

D1

51

VSS550

P0.326

P0.222

1_SEG6

Q3BC847AL

23

1

2_SEG1

1_SEG7

2_SEG22_SEG3

2_SEG0

2_SEG52_SEG4

2_SEG62_SEG7

U10

7 SEG DISP

E1 D2

CA

13

C4

DP5

B6 A7

CA

28

F9

G10

2_SEG1



C Program to I2C – 7 Segment Display using LPC2148 ***************************************************************************************

Title : Program to I2C - Seven Segment display ***************************************************************************************

#include <LPC214x.h>

#include <stdio.h>

#define MAX 6

#define AA 2

#define SI 3

#define STO 4

#define STA 5

#define I2EN 6

void I2C_ISR(void)__irq;

void Wait (unsigned int);

void I2C_Init (void);

int I2C_Start (void);

int I2C_Write (unsigned char *Buff, unsigned int Count);

unsigned char Buff[] = {0x00,0x27,0x3F,0x06,0x5B,0x4F};

unsigned char index = 0;

void I2C_ISR(void)__irq

{

if (I2C0CONSET & 0x08)

{

switch (I2C0STAT)

{

case (0x08):

I2C0CONCLR = 1 << STA;

I2C0DAT = 0x70; //Slave Addr + W

break;



case (0x10):

I2C0CONCLR = 1 << STA; //Clear START Bit

I2C0DAT = 0x70;

break;

case (0x18):

I2C0CONCLR = 0x20; //Clear START Bit

I2C0DAT = Buff[index];

index++;

break;

case (0x20):



index++;

break;

case (0x28):


if (index < MAX)

{


index++;

}

else

{

index = 0;

I2C0CONSET = 0x10; //Send STOP Bit

}

break;



case (0x30):


if (index < MAX)

{


index++;

}

else

{

index = 0;

I2C0CONSET = 0x10; //Send STOP Bit

I2C_Start();

}

break;

case (0x38):

I2C0CONSET = 0x20;

break;

}

}

I2C0CONCLR = 1 << SI;

VICVectAddr = 0x00;

}

void main()

{

unsigned int i;

VPBDIV = 0x02;

PINSEL0 = 0x00000055; // P0.3 - SDA0 & P0.2 - SCL0

U0LCR = 0x83;

U0DLL = 97;

U0DLM = 0x00;

U0LCR = 0x03;



VICIntSelect = 0<<9;

VICVectCntl0 = 0x020 | 9 ;

VICVectAddr0 = (unsigned long)I2C_ISR;

VICIntEnable = 1<<9;

I2C_Init();

I2C_Start ();

for (i=0;i<30;i++) Wait(10000);

I2C0CONCLR = 1 << SI;

while(1)

{

for (i=0;i<20;i++) Wait(10000);

}

}

void Delay(void)

{

unsigned int i,j;

for(i=0;i<20;i++)

for(j=0;j<200;j++);

}

void Wait (unsigned int Delay)

{

while(Delay--);

}

void I2C_Init (void)

{

I2C0SCLH = 150; //50%duty,I2C Freq ->100KHz, PCLK = 30MHz

I2C0SCLL = 150;

I2C0CONSET = 1 << I2EN; //Enable I2C 0

}



int I2C_Start (void)

{

I2C0CONCLR = 1 << STO;

I2C0CONCLR = 1 << AA;

I2C0CONSET = 1 << STA;

return 0;

}

int I2C_Write (unsigned char *Buff, unsigned int Count)

{

while(Count--)

{

I2C0DAT = *Buff++;

}

return 0;

}

To compile the above C code you need the KEIL

software. They must be properly set up and a project with

correct settings must be created in order to compile the

code. To compile the above code, the C file must be added

to the project.

In Keil, you want to develop or debug the project

without any hardware setup. You must compile the code for

generating HEX file. In debugging Mode, you want to check

the port output without LPC2148 Primer Board.

The Flash Magic software is used to download the hex

file into your microcontroller IC LPC2148 through UART0.



Testing the I2C – Seven segment with LPC2148

Give +3.3V power supply to LPC2148 Primer Board; the

four seven segment display is connected with the LPC2148

Primer Board. First check the entire seven segments LED’s

are properly working or not.

Here we are display just 1234 in four seven segment.

The entire seven segments receive it through I2C & display

it in order.

If any data is not coming in seven segments, then you

just check the entire seven segments LED’s are working or

not. Change the seven segment driver IC & Check the I2C

connections. Check the four seven segments connections.

Otherwise you just check the code with debugging mode in

Keil. If you want to see more details about debugging just

see the videos in below link.

How to Create & Debug a Project in Keil.

http://youtu.be/EzOCple4POk



General Information

For proper working use the components of exact values

as shown in Circuit file. Wherever possible use new

components.

Solder everything in a clean way. A major problem

arises due to improper soldering, solder jumps and

loose joints.

Use the exact value crystal shown in schematic.

More instructions are available in following articles,

Interfacing UART with LPC2148 Microcontroller.

Interfacing Keys with LPC2148 Microcontroller.

User Manual of LPC2148 Primer Board.

Tutorial of how to create & Debug a project in Keil.

http://www.pantechsolutions.net/index.php?option=com_k2&view=item&layout=item&id=665&virtuemart_category_id=1&Itemid=19






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ARM HOW-TO GUIDE Interfacing I2C-7SEG with LPC2148 · PDF file13-12-2014 · Circuit Diagram to Interface I2C–7 seg with LPC2148 ... User Manual of LPC2148 Primer Board. Tutorial