Pic25k20 PWM Amicus board incorrect freq

[pic-ignorant]

I used a 12F683 (hardware pwm)to get modulated IR @ 38Khz. Works really well

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[Tim]

I would have used a 12f683 if I had one here. The issue was I could not wait to order one. I needed to update the client by today which is why I purchased the kit from Maplins as they had it in stock at a local store.

[Les]

I've never had a problem with 18F25K20 device and PWM. So just to prove to myself that the chip is not at fault I wrote a simple snippet program to configure the PWM for 36KHz and 38KHz and ran it in the ISIS simulator. The results were as expected:

    Device = 18F25K20
    Declare  Xtal  = 4
    Declare Optimiser_Level = 1
    
' For Approx 36KHz 50% duty cycle (Actually 35.715KHz) 
(*
    T2CON = %00000100  
    PR2 = 27          
    CCPR1L = % 00001110        
    CCP1CON = % 00001100 
    Output PORTC.2
*)  
' For Approx 38KHz 50% duty cycle (Actually 38.461KHz) 

    T2CON = %00000100  
    PR2 = 25          
    CCPR1L = %00001101         
    CCP1CON = %00001100 
    Output  PORTC .2

If you were running your tests on the Amicus18 platform, did you remember that Amicus18 uses a 16MHz crystal, but your program is set for a 4MHz crystal.

[pic-ignorant]

Oh OK. If you wanted me to try out some code, I have a some 12f683 boards and loose pics at work if its any help

[Les]

I've also noticed in your configs that you have XINST set to On. This will cause havoc with standard programs.

[Tim]

Since I gave up trying it on the real board it was all done in a sim and the sim had the clock set to 16 Mhz. All the calculations for the PWM were don on a 16mhz clock.

I tried the code posted in a sim and it did not run with out the proper fuses settings When I added them in it did run but not at 36 or 38 khz with the extal at either 4 or 16mhz.

I spent a lot of time trying to find out what freq the Amicus board runs at by default. The only reference I could find was a post saying it was 64mhz and a simple delayms test seemed to confirm that. (real hardware) So any further tests I did were programmed via my Pickit2 were I turned of the PLL.

Anyway now I have given up, I was only using the Amicus to save time as it was powered via USB etc but now I have another dev board I do not need it.