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amboleos
Joined: 13 Oct 2010
Posts: 8
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| i2c state problem |
 Posted: Wed Oct 13, 2010 7:57 am |
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Hi all,
I have problems with I2C. I need to connect 3 PIC to one master but after six hour, I could only write to one slave. I tried every tutorial and code that I found but in proteus they don't work.
I can see that master passes the info to slave and slave executes
| Code: | | i2c_write(buffer[address]); |
but master reads this value as 0x80 which equal to the state value in that period.
Here is my master code
| Code: |
#include <16F877A.h>
#include "2401.c"
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#use i2c(MASTER, SDA=PIN_C4, SCL=PIN_C3)
int8 data=0;
int8 data1=0;
void main()
{
init_ext_eeprom(); //Call before the other functions are used ////
delay_ms(100);
data=read_ext_eeprom(2); //Read the byte d from the address a ////
delay_ms(100); ////
write_ext_eeprom(2, 15); // Write the byte d to the address a ////
delay_ms(100);
data=read_ext_eeprom(2); //Read the byte d from the address a ////
////
data1 = ext_eeprom_ready(); //Returns TRUE if the eeprom is ready ////
//to receive opcodes ////
///
} |
and slave
| Code: | #include <16F877A.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0xA0)
BYTE address, buffer[0x10];
BYTE incoming, state;
#INT_SSP
void ssp_interupt ()
{
state = i2c_isr_state();
if(state <= 0x80) //Master is sending data
{
incoming = i2c_read();
if(state == 1) //First received byte is address
address = incoming;
if(state == 2) //Second received byte is data
buffer[address] = incoming;
}
if(state == 0x80) //Master is requesting data
{
i2c_write(buffer[address]);
}
}
void main ()
{
enable_interrupts(GLOBAL);
enable_interrupts(INT_SSP);
buffer[0]=23;
buffer[1]=24;
buffer[2]=25;
buffer[3]=26;
buffer[4]=27;
while (TRUE) {}
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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amboleos
Joined: 13 Oct 2010
Posts: 8
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| Posted: Thu Oct 14, 2010 2:51 am |
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Thank you for links, I tried the these codes that are supposed to be working.
Meanwhile my complier is PCWHD 4.112
Master
| Code: | #include <18f4520.h>
#fuses HS, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#use i2c(Master, sda=PIN_C4, scl=PIN_C3)
#define SLAVE1_WRT_ADDR 0x14
#define SLAVE1_READ_ADDR 0x15
#define SLAVE2_WRT_ADDR 0x28
#define SLAVE2_READ_ADDR 0x29
#define SLAVE3_WRT_ADDR 0x42
#define SLAVE3_READ_ADDR 0x43
//====================================
void main()
{
int8 data1,data2,data3;
while(1)
{
output_high(pin_d4);
delay_ms(60);
output_low(pin_d4);
i2c_start();
i2c_write(SLAVE1_READ_ADDR);
data1 = i2c_read(0);
i2c_stop();
delay_ms(10);
i2c_start();
i2c_write(SLAVE2_READ_ADDR);
data2 = i2c_read(0);
i2c_stop();
delay_ms(10);
i2c_start();
i2c_write(SLAVE3_READ_ADDR);
data3 = i2c_read(0);
i2c_stop();
printf(" [ %3U %3U %3U ] \r\n", data1,data2,data3);
output_high(pin_d6);
delay_ms(60);
output_low(pin_d6);
}
} |
my slave (just one slave is connected to the bus)
| Code: | #include <18F4520.h>
#device adc=8
#fuses HS,NOWDT,PUT,BROWNOUT,NOLVP
#use delay(clock=20000000)
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0x14)
int8 adc_result;
#INT_SSP
void ssp_interrupt()
{
int8 incoming, state;
state = i2c_isr_state();
if(state < 0x80) // Master is sending data
{
incoming = i2c_read();
}
if(state >= 0x80) // Master is requesting data from slave
{
i2c_write(14);
}
}
//======================================
void main ()
{
setup_adc_ports(AN0);
setup_adc(ADC_CLOCK_DIV_8);
set_adc_channel(0);
delay_us(20);
adc_result = read_adc();
enable_interrupts(INT_SSP);
enable_interrupts(GLOBAL);
while(1)
{
adc_result = read_adc();
delay_ms(500);
}
} |
My results
| Code: | [14 255 255]
[255 255 255]
[255 255 255]
[255 255 255]
.... |
Just the first time, value is correctly readed. 
I also tried to clear all other slave codes and just let 1 slave and master communicate, but again it didnt work.
Problem is that slave never enters interrupt again after first one. |
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temtronic
Joined: 01 Jul 2010
Posts: 9241
Location: Greensville,Ontario
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| Posted: Thu Oct 14, 2010 5:39 am |
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If this is a simulator (proteus) it may not be your code but the simulator!
I've never trusted any simulator in the 35 years I've been cutting code.
NONE will work 100% properly all of the time.
If real hardware, check the pullups for right values for your speed, board layout, etc. |
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