I am using two pic controllers

I want to know how to use the I2C to send data from master to slave

I want to send a count value from the master PIC, the slave should read that count value and accordingly set or reset one of its port bits for example PORTA,5 depending on the count value

If anyone has an idea please let me know

Thanks

 

Any ideas to send the data from master PIC to the slave PIC using i2C??

 

Good questions draw good answers. As most us in this forum are not clairvoyant. So a good start would be to post imperative information like any code and schematics you have.

 

this is I2C, if you use the datasheet, you need to set up the address for your i2c slave, i.e.: 01010101 therefore everytime your masters wants to communicated, you use the standard I2C functions to communicate with address 01010101.. sending your data across..?
make sense?
like t06afre says though, schematics etc will help, dont even know what pic models youre using!

 

I implemented the following subroutine which works perfectly fine when I send data from the master PIC to a digital potentiometer AD5245

But AD5245 has a specific device ID

Pot_0:
;{
call I2C_STRT////Start I2C communication subroutine
movlw 0x58 //////Device ID (address)for digital pot
movwf I2C_Value
call I2C_SEND
movlw 0x00
movwf I2C_Value
call I2C_SEND
movlw 0x79
movwf I2C_Value
call I2C_SEND/////Send data
call I2C_STP/////Stop subroutine
return
Now I want to implement something similar but use PIC16f887 as slave

The Master PIC is PIC18f67J90

If anyone has an idea please let me know

Thanks

 

PIC16F887 Datasheet page 187. chapter "13.4.1 Slave Mode"
like i said, you need to set the MSSP up so you can use I2C slave, 7 or 10 bit address..
then you need to give it the address so 0101010 or whatever isnt being used in your system.
then you need to communicate. as normal.
yes?

 

and please use code tags.

 

I did try setting the MSSP I2C slave, 7 or 10 bit address but it didn't work

Do i need to set it for the master PIC also?

 

no, you do need to set the address though?
and then write to that address from the master?
SSPADD i think is the register you need to put the address in. again check the datasheet, it has the method of communication for it
from the master side -
standard I2C comms, use the address of your slave, and transmit the data you want as standard

 

Now I know how to transfer the data from master to slave

But I am not able to read the data from the slave

For master to slave I used the following code:

Master PIC subroutine:

call I2C_STRT
movlw 0x40
movwf I2C_Value
call I2C_SEND
movlw 0x00
movwf I2C_Value
call I2C_SEND
movlw d'10'///////data to be sent to slave PIC
movwf I2C_Value
call I2C_SEND
call I2C_STP
return

I implemented the Slave PIC subroutine in the interrupt Service routine:

btfss PIR1,3
goto $
bcf PIR1,3

btfsc SSPSTAT,5
call label_data

retfie

label_data:
movf SSPBUF,0
movwf TEMP////register to store data received from master pic
return

Above code worked perfectly for master to slave

But now I am having issues in reading the data from slave to master

 

so to clarify, you are transmitting the data from master to slave? but you cannot read the data? try pausing the program and having a look at the SSPBUF make sure the data youve sent is actually there.. then you know 100% its being transmited and the addressing is right..
ALSO please remember to use code tags. try editing your post if you can and using them (# button at top of reply window) it makes things so much easier to understand

 

chrisw, I believe he has two PICs communicating via I2C, one master (which he has working) and a slave (which is not working).

rg23: I recently found a code example, I2C module in PIC18F4685 is configured as slave by Microchip. I have an upcoming need to make a slave unit so I'm re-researching it; I did it once but I am no longer with the company I left that code with.

I've yet to delve into this project.

 

i know, im trying to establish whether he actually has the communication correct at the moment.. though its triggering the interrupt for reception, and it wouldnt be if it wasnt.. obviously..