different software times, impossible?

[lutherblisset]

hi richard, i understand. The 31-479 possible pulses of y for every 400 pulses of x are for me necessary, it's impossible for me to change those three parameters. i know it's a problem of "times", they are like two "digital gears" and i must find the way to match the reciprocal "teeth". The frequency of x now is 1666 hz (240.000uS) but the x motor accept other frequencies too. More difficult for me is understand interrupts, overflow, ticks, to find my way and the possible solution

[richard]

More difficult for me is understand interrupts, overflow, ticks, to find my way and the possible solution

the forum is crammed full of examples

search "blinky" to see some relevant ideas

perhaps if you provide more detailed information about what you are trying to achieve preferably with some examples of the code that you have tried , more help would be offered.
as it stands your goal is a mystery and worse still the goalposts seem to keep moving . speculation wastes everyone time and patience.
(I'm thinking now that an electronically variable gearbox might be your target , if so this approach is not going to work) but that's just speculation

[lutherblisset]

anyway the pwm (the only way to have two pulses on different ports of a pic at the same time) it's not good for me cause i work with stepper motors and i have to define closed number of steps, not frequencies. Cause i must define fix numbers, not number of pulses for second. I can't tell the pic to count until 9600 on a port and to count until 120000 on another port at the same time (the quartz of course) its impossible.

[amgen]

from what you have described so far, it may be easier than it seems to implement this..... maybe.
1, you have to use timer interrupt at 50micro seconds..... the highest common value for both times
2, you implement a while/wend loop with block of code for main X....hi/low and total run ... and block of code for Y .... with values you calculated
3, using counters in blocks to toggle pins and exit while when pulses/count are reached
4, outside of while blocks to get/calculate new Y's.... do other stuff then startup a new round of pulses
5, the constraint is all the code inside blocks have to be less than 50micro seconds..... at 20 MHZ should able to do about 100 to 200 instructions in 50micro seconds

[lutherblisset]

thank you amgen, i have to work with the timers for generate the correct number of pulses for two ports with the lowest possible latency.