How can i use two PIC micro controllers working synchronic?

Question

I have a circuit with two PIC micros and they are moving some motors . i want them two move motors in a same time. help me what can i do ? ( can i use common crystal ?) also i am using 4MHz crystal.

Answer 1

By the time the 4 MHz crystal signal is divided down inside the PIC to an individual set of instructions for motor motion, the 2 PICs would be close enough to each other if they used separate 4 MHz crystals.   I doubt you will be sending any commands to an winding driver every 250 nanoseconds (1/ 4MHz).  The driver transistors or MOSFETs probably won't even respond in less than a couple of microseconds.

What you need to do is to use a port output from one PIC to drive an interrupt on the other PIC, and vice-versa.  In real-time-operating systems, these are called semaphores.  Having the 2 PICs 'talk' to one another constantly will keep them in synchronization.  Each of the interrupts should force the PICs into a known state.  A timer should time out to drive the interrupt in the other PIC.  That way, if the frequency is off by a few percent, it can be compensated for in time with the timer.

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Answer 2

you have to drive them with the same clock signal but not directly by the same crystal. better search the web