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jallum
Joined: 05 Mar 2008
Posts: 9
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| Master and slave I2C implemented on one PIC |
 Posted: Thu Mar 06, 2008 1:33 pm |
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If you are trying to set up your PIC as master of an I2C bus using SW implementation, and slave of an altogether different bus (or even the same bus I suppose) using the HW SSP module, here is some code for you:
| Code: |
#include <16F877A.h>
#device adc=10
#FUSES NOWDT //No Watch Dog Timer
#FUSES HS //High speed Osc (> 4mhz)
#FUSES PUT //Power Up Timer
#FUSES PROTECT //Code protected from reads
#FUSES NODEBUG //No Debug mode for ICD
#FUSES BROWNOUT //Brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD //No EE protection
#FUSES NOWRT //Program memory not write protected
#use delay(clock=20M)
//NOTE: Must declare MASTER before SLAVE, i2c_isr_state() returns 0
// when MASTER is the most recent #use i2c
#use i2c(MASTER, sda=PIN_C1, scl=PIN_C0, stream=I2CM)
#use i2c(SLAVE, sda=PIN_C4, scl=PIN_C3, address=0x60, force_hw, stream=I2CS)
#use rs232(baud=57600, parity=N, xmit=PIN_C6, rcv=PIN_C7, bits=8, stream=COM1)
#use fast_io(D)
int rcv_buf[0x10];
int wrt_buf[0x10];
int cmd=0xFF;
#int_SSP // interrupt on i2c activity
void i2c_isr(void)
{
int state, incoming;
state = i2c_isr_state();
if(state < 0x80)
{
incoming = i2c_read(I2CS);
if (state == 1)
{
cmd = incoming;
}
else if (state > 1)
{
rcv_buf[state-2]=incoming;
}
}
else
{
i2c_write(I2CS,wrt_buf[state-0x80]);
}
}
void main()
{
enable_interrupts(INT_SSP);
enable_interrupts(GLOBAL);
printf("\n\rbegin");
while (TRUE)
{
if (cmd<0xFF)
printf("\n\rcmd: %x", cmd);
i2c_start(I2CM);
i2c_write(I2CM,0xa0); //i2c address of a slave device
i2c_write(I2CM,0x2e); //1st byte to slave
i2c_write(I2CM,0xa0); //2nd byte to slave
i2c_stop(I2CM);
}
}
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It is VERY important to declare the SLAVE after the MASTER. It appears that i2c_isr_state() will return 0 if the MASTER declaration is the most recently encountered #use statement, although i2c_isr_state() should only read the state of the SLAVE SSP hardware. |
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XyVy
Joined: 10 Sep 2008
Posts: 2
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| Posted: Wed Sep 10, 2008 3:16 am |
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Hello Jallum, I need to do work i2c master and slave in the same PIC, but when I introduce the #use i2c(master...) the slave side does not work, but if I delete the #use i2c(master...) line, the slave side works okey again.
What is wrong?
My code is:
| Code: |
#include <16F876A.h>
#FUSES NOWDT //No Watch Dog Timer
#FUSES XT //Crystal osc <= 4mhz
#FUSES NOPUT //No Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD //No EE protection
#FUSES NOWRT //Program memory not write protected
#use delay(clock=4000000)
#byte port_b=0x06
#use i2c(MASTER, FAST, sda=PIN_A0, scl=PIN_A1, address=0xB0, force_sw, stream=i2cM)
#use i2c(SLAVE, FAST, sda=PIN_C4, scl=PIN_C3, address = 0x08, force_hw, stream = i2cS)
// Comandos soportados por el PIC 16F876 en nuestro software
#define INIT 0x01
#define CONSULTA_MOTOR1 0x02
#define CONSULTA_MOTOR2 0x03
#define MUEVE_MOTOR1 0x04
#define MUEVE_MOTOR2 0x05
#define INTERRUPTOR1 0x06
#define INTERRUPTOR2 0x07
#define INTERRUPTOR3 0x08
#define INTERRUPTOR4 0x09
#define STOP_MOTOR1 0x0A
#define STOP_MOTOR2 0x0B
// definimos los datos para usar i2c
char data;
char cuenta;
BYTE state;
BYTE comando;
BYTE dato;
void inicializa()
{
output_high(PIN_B2);
i2c_start(i2cM);
i2c_write(i2cM, 0xB0); // Dirección del dispositivo
i2c_write(i2cM, 0x00); // Registro de Modo
i2c_write(i2cM, 0x01); // Motor1 detenido
i2c_stop(i2cM);
output_low(PIN_B2);
}
void MueveMotor1(char dato)
{
output_high(PIN_B2);
i2c_start(i2cM);
i2c_write(i2cM, 0xB0); // Dirección del dispositivo
i2c_write(i2cM, 0x01); // Registro de modo
i2c_write(i2cM, dato); // Registro Velocidad motor 1
i2c_stop(i2cM);
output_low(PIN_B2);
}
void MueveMotor2(char dato)
{
output_high(PIN_B2);
i2c_start(i2cM);
i2c_write(i2cM, 0xB0); // Dirección del dispositivo
i2c_write(i2cM, 0x02); // Velocidad de los motores
i2c_write(i2cM, dato); // Velocidad del motor2
i2c_stop(i2cM);
output_low(PIN_B2);
}
void StopMotor1()
{
output_high(PIN_B2);
i2c_start(i2cM);
i2c_write(i2cM, 0xB0); // Dirección del dispositivo
i2c_write(i2cM, 0x01); // Registro de Modo
i2c_write(i2cM, 128);
i2c_stop(i2cM);
output_low(PIN_B2);
}
void StopMotor2()
{
output_high(PIN_B2);
i2c_start(i2cM);
i2c_write(i2cM, 0xB0); // Dirección del dispositivo
i2c_write(i2cM, 0x02); // Velocidad de los motores
i2c_write(i2cM, 128); // velocidad del motor1
i2c_stop(i2cM);
output_low(PIN_B2);
}
#INT_SSP
void ssp_interupt ()
{
state = i2c_isr_state();
if(state<0x80) //master is sending data
{
if(state == 0)
{
} else if (state == 1) //first received byte
{
output_high(PIN_B2);
comando = i2c_read(i2cS);
} if (state==2) { // 2º byte recibido
dato=i2c_read(i2cS);
}
}else if (state == 0x80) { //master is requesting data
output_high(PIN_B1);
if (input(PIN_B4)) {
i2c_write(i2cS, 1);
} else {
i2c_write(i2cS, 0);
}
i2c_write(i2cS, cuenta); //send requested data
cuenta++;
}
}
void main()
{
char data;
int pulsado=0;
char sw=0;
int activo;
cuenta=0;
port_b=0;
enable_interrupts(GLOBAL);
enable_interrupts(INT_SSP);
sw=0;
pulsado=0;
while (1) {
activo=input(PIN_B4);
if (activo && (sw==0) && (!pulsado)) {
output_low(PIN_B2);
MueveMotor1(255);
StopMotor2();
pulsado=1;
sw=1;
} else if (activo && (sw==1) && (!pulsado)) {
output_high(PIN_B2);
MueveMotor2(255);
StopMotor1();
pulsado=1;
sw=0;
}
delay_ms(50);
if (!input(PIN_B4)) {
output_low(PIN_B2);
pulsado=0;
}
delay_ms(50);
}
}
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Thanks in advance! |
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XyVy
Joined: 10 Sep 2008
Posts: 2
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| Posted: Thu Sep 11, 2008 2:40 am |
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Good news guys!
I have solved my problem.
I put the uses like:
#use i2c(MASTER, sda=PIN_A0, scl=PIN_A1, address=0xB0, stream=i2cM)
#use i2c(SLAVE, sda=PIN_C4, scl=PIN_C3, address = 0x08, force_hw, stream = i2cS)
But, I believe the problem was in the following function:
| Code: |
#INT_SSP
void ssp_interupt ()
{
state = i2c_isr_state(i2cS);
if(state<0x80) //master is sending data
{
if(state == 0)
{
} else if (state == 1) //first received byte
{
output_high(PIN_B2);
comando = i2c_read(i2cS);
} if (state==2) { // 2º byte recibido
dato=i2c_read(i2cS);
}
}else if (state == 0x80) { //master is requesting data
output_high(PIN_B1);
if (input(PIN_B4)) {
i2c_write(i2cS, 1);
} else {
i2c_write(i2cS, 0);
}
i2c_write(i2cS, cuenta); //send requested data
cuenta++;
}
}
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I forgot put the "i2cS" stream in the i2c_isr_state.
The PIC works okey!!
Thanks! |
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