how to generate two signals from two ports at the same time by using p16f84

[bikxsici]

yes, i have tried it also, i put them in main loop but i could not obtain time accuracy.

[bikxsici]

i need a loop with constant 8 mic. sec. time period and multiplying it with two different variables to obtain to different signal. but how?

[mackrackit]

How fast are you allowed to run the MCU?

[mackrackit]

http://www.picbasic.co.uk/forum/cont....-PICMultiCalc

[bikxsici]

i am allowed to use pic16f84 and 10 mhz crystal. i think this project is impossible, since i have struggled so much, but unfortunately he has a circuit doing that with pic16f84 :0

[bikxsici]

thanks a lot mackrackit

that utility makes me more careful about timer. now let me review my program again

[cncmachineguy]

Your first post said you needed to be able to select 2 frequencies. How are they selected? If they are just hardcoded in and there is nothing in the "main", there is no need for an interrupt. You can do it all from the main routine. This will save all the time required to process the interrupt.your code would have 1 line looking for the timer overflow such as :

while !tmr0 overflow
wend

then load 2 counters, 1 for each output

freq1 = period / timer0
freq2 = period2 / timer0

then on each overflow, decrement the freq's. when 1 reaches zero

if !freq then
 toggle output bit
 reload freq
endif

now don't forget to reload the timer unless you can set it up to just free run. You will need to play with the freq's counter numbers to "tune" the output, but I suspect you can get it right on the money.

[bikxsici]

hi cncmachineguy

dividing two variables by tmr0 and obtaining two periods from tmr0, it seems to work, but i think there can be some problems. for example, should we reload tmr0 with respect to which signal? for the first pulses ok but then when next period start?

program below is what you said, isn't it? thank you for advices

    OPTION_REG=%00000000
    TMR0=0
    INTCON=%10100000
main:
    while   tmr0>=250 
    tmr0= 0
    wend
      
    freq1= per1 / timer0
    freq2= per2 / timer0
    
    if  freq1<1 then    
    toggle  a0
    per1=100
    else
    endif
    
    if  freq2<1 then    
    toggle  a0
    per2=200
    else
    endif
    goto    main