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Raspberry B+ i2c PIC 18F4550 Slave problem.

 
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freebee



Joined: 25 Nov 2014
Posts: 1

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Raspberry B+ i2c PIC 18F4550 Slave problem.
PostPosted: Tue Nov 25, 2014 11:21 am     Reply with quote
hi for all,

I am very novice in code and i want just send string from a pic to a raspberry pi. Raspberry b+ is just i2c master and pic just slave.

Code for i2c pic slave:
Code:
#include <18F4550.h>
#device adc=10
#fuses XT, NOWDT, PUT, BROWNOUT, NOLVP
#use delay(clock=20Mhz)
#define PIC_TRIS_B 0b00000011 // Input mode B0 and B1
#use i2c(Slave, Slow, sda=PIN_B0, scl=PIN_B1, address=0x08)


//==========================
void main()
{

i2c_start();
while(1)
  { 
   i2c_write(0x55);
   delay_us(500);
  }

}

The idea is just send a data to raspberry pi.
This code compiles, but no send data. Can somebody help me ?.
Ttelmah



Joined: 11 Mar 2010
Posts: 19552

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PostPosted: Tue Nov 25, 2014 11:56 am     Reply with quote
Look at the slave example.

All I2C transactions are initiated by the master. A slave cannot send a start.

The slave has to wait for the master to send a data request, with the correct address, and _then_ load the byte for the reply.

As a comment, have you actually tested your PIC is working?. XT, and 20MHz, are _not_ legal clock settings.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Tue Nov 25, 2014 12:37 pm     Reply with quote
Here is a post that explains how to setup a simple i2c master and
slave, by using the CCS example file, ex_slave.c:
http://www.ccsinfo.com/forum/viewtopic.php?t=50861&start=1
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