variable PWM with 12F1572

[HackInBlack]

adapted from an example file;the pushbutton 'should' change the duty-cycle on channel 1,but won't do anything...can anyone see whats wrong?

chip 12F1572, 32

   ' #config mclr=on   'use bushbutton on GPIO.3 as input
    #define SWITCH_PORT GPIO.3

    Dir SWITCH_PORT In

    Dir PORTA Out

    Do
  If SWITCH_PORT = 0 Then

    #define HPWM16_1_Freq 100         '100khz
    #define HPWM16_1_Duty 5           '5% duty DS2 barely lit
    HPWM16On ( 1 )

    else

    #define HPWM16_1_Freq 200         '200khz
    #define HPWM16_1_Duty 100         '100% duty
    HPWM16On ( 1 )

    #define HPWM16_3_Freq 300         '300khz
    #define HPWM16_3_Duty 60          '60% duty DS3 brighter
    HPWM16On ( 3 )

    End If
Loop

[kent_twt4]

The Switch_Port In is overwritten by PortA Out. Could set each individual pin, or use TrisA = 0b001000

[HackInBlack]

i've changed 'DIR porta out' to 'TrisA = 0b001000' but the switch still has no effect;the chip is outputting the correct PWM but it won't change on the button press...

[Anobium]

You are using fixed mode PWM. The frequency and duty are fixed at the frequency and duty as specified by the PWM constants. As you cannot change the constants in your running program what you are getting is the correct behaviour for fixed mode.

You need to use Variable mode PWM.

[HackInBlack]

i thought obout that just before you posted! its 'set and forget' PWM...now to try the same idea using variable PWM.if i can get my head round the examples...still at least it does output 2 PWM waveforms albeit on seperate pins! why only2? simple..the lowpincount board only has 2 'linked' LEDs.

[Anobium]

See C:\GCB@Syn\GreatCowBasic\Demos\pwm_solutions\pic_pwm16_examples in your installation. There are a lot of demos specific to your chosen chip.

[HackInBlack]

#chip 12F1572, 32

#define SWITCH_PORT GPIO.3
Dir PORTA Out
TrisA = 0b001000

 Do
  If SWITCH_PORT = 0 Then

HPWM16(1, 10, 16384)   '10 kHz, 25% duty cycle (16384/65535)

else

HPWM16(1, 80, 16384)   '80 kHz, 25% duty cycle (16384/65535)

HPWM16(3, 30, 16384)   '30 kHz, 25% duty cycle (16384/65535)

End if
loop

' not sure if the 80 is right but at least its visible! and it works as expected

[Anobium]

Excellent news.

Enjoy