Interfacing two PIC24's together

mharris27 · Joined: 22 Apr 2005 Posts: 15

Has anyone successfully been able to interface two PIC24 micro's togther using I2C?

I am trying but I have little experience with the I2C protocol. I can find lots of info on interfacing a pic24 with a memory device but not with another pic24.

All I want to do is send data one way (from the master to slave) the slave processor will be idle until it sees data that is addressed to it on the I2C bus and then it will exicute a desired rutine. Any advice would be appreciated.

ECACE · Joined: 24 Jul 2006 Posts: 94

Look in your PICC/Examples directory for the file: EX_SLAVE.C

That is an example of the PIC in I2C Slave mode, where the PIC is acting like it is a memory device. Understand that one along with the ones you mentioned of the PIC accessing memory devices. In those cases, the PIC would be the master. You will then have both sides of the code and should be able to get it to work.

I would strongly suggest that you get the PIC accessing a memory device to work correctly first, and understand exaclty what is going on with it. Do not start with code trying to do both sides up front. If your code is working for the master side, then and only then try to get the Slave side to work. Debugging two sides of communication and not knowing which one is failing can be quite a challenge.

Good luck.
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mharris27 · Joined: 22 Apr 2005 Posts: 15

Thanks for the response...I have looked at the .c file that you recommended...the problem is this. The PIC24H256GP210 does not recognize the #INT_SSP or any of the enable_interrupts commands. I have looked thru the header file and they are not listed. It's my understanding that the I2C intrrupts are all automatic for hese micros no?

Thanks,
Mike

ECACE · Joined: 24 Jul 2006 Posts: 94

If there is nothing about the interupt enables in the header file specific to your processor, then that would explain the problem. I don't have PCD, so I can't look at the PIC24 header files. Sorry.
If that is the case though, I would suggest you call/email CCS. I have heard there are bugs in the PCD compiler. Perhaps you have found a new one? Sorry I couldn't be of more help. Maybe someone else on the forum is familiar with it.

FYI, in the future, you should always post your compiler version, processor in question, and a code snippet if possible. It can really help in trying to determine what your problem may be.

Good luck.
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FvM · Joined: 27 Aug 2008 Posts: 2337 Location: Germany

To learn the expected #int_xxx names with PCD, you should consult the View - Valid Interrupts page in PCWHD IDE. They are e. g. #int_si2c, #int_si2c2 or #int_si2c3 for I2C slave interrupt. I guess, other details may also need to be corrected when porting the said example program to PCD.