master and 3 slaves PIC

[David]

Hi

I want use CCS do program of communication between 1 master PIC (18F452) and 3 Slaves PIC(18F452), the salve PIC has different address. which is the best way for this program.
I used Intel MCS51 for a similar project before, the MCS51 has multiprocessor communication mode. but I don't know how about PIC.
Thanks,
Merry Christmas and happy new year!

David

[TSchultz]

I have used both I2C and SPI for this type of communication before if the PICS are all on the same board. I have also used multi-drop RS485 when they are on different boards.

One thing I find helpfull for interprocess communications is to add a couple of handshaking lines to ease to process. I like the SPI interface best and in addition to chip select, I add a busy pin to each of the slaves.

The busy can then be used to indicate when the slave is doing something that should not be interrupted. With some thought and knowledge of how the firmware is written it is also possible to write the routines to keep the slave and master code flow so it can be synchronized if necessary.

As with any interprocess data bus you need to have a way to control the use of the bus so you don't have contention problems.