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I2C Slave, i2c_poll returns

 
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Matt.
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I2C Slave, i2c_poll returns
PostPosted: Tue Jan 16, 2007 9:59 am     Reply with quote
Hello all,

I use a 16F877 as a slave and a very simple code.
I poll data in a while ( while (!i2c_poll) ) and then do an i2c_read
When with the master board (another system) I send data on the i2c bus, my program goes in the while (so, i2c_poll found some data to get). I then do an i2c_read, but it hangs here. i2c_read does not return. OK1 is outputed on the RS232, but not the OK2
Does anybody have an idea of what it could be ?
Regards,

Matt.
Code:

#include <16F877.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)
 

void main()
{
      puts("I2C TRACES");
i2c_start();
 
while(!i2c_poll())
{
   puts("OK1");
   test = i2c_read();
   puts("OK2");
}
i2c_stop();
while (true)
   {
 
   }
}
rnielsen



Joined: 23 Sep 2003
Posts: 852
Location: Utah

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PostPosted: Tue Jan 16, 2007 11:20 am     Reply with quote
I would suggest you use the hardware that is on the PIC to do your I2C reception. You are using a software I2C and the hardware will be much more effective. Put some code in the ISR and start your experimenting there. There are boat loads of posts regarding this stuff and you can get a good start from them.

Ronald
Matt.
Guest
PostPosted: Wed Jan 17, 2007 2:09 am     Reply with quote
Even with ISR it does not work. I guess it is a hardware problem ...
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Jan 17, 2007 2:28 am     Reply with quote
Your slave code is incorrect. I2c slaves don't do start and stop bits.
The master does those operations.

Also, when you specify "SLAVE" in the #use i2c statement, the compiler
will automatically use the hardware i2c module, if the hardware pins are
also specified.

Look at the CCS example file on how to do an i2c slave. It's called
Ex_Slave.c and it's in this folder: c:\Program Files\Picc\Examples
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