3 channel PWM with customize duty cycle

[HenrikOlsson]

Hi,
Perhaps you could do something like:

For i = 0 to 2
  Phase(i) = Phase(i) + 1
  If Phase(i) > 185 then
    Phase(i) = 0         'When pointer is > 185 we need to wrap around to 0.
    Gosub ChangeBridgeDrive                  'One phase is starting over, go change the outputs.
  ENDIF
NEXT

And the ChangeBridgeDrive subroutine might then look something like:

ChangeBridgeDrive:
 
' When we come here the value i contains the phase counter that just got reset so we
' can use that to determine for which phase we should switch the outputs.
 
Select Case i
    Case 0                          ' It was Phase 1 that rolled over
        TOGGLE PORTA.1              ' Invert the state of the pin
        TOGGLE PORTA.2              ' Invert the state of the pin
 
    Case 1                          ' It was Phase 2 that rolled over
        TOGGLE PortB.1              ' Invert the state of the pin
        TOGGLE PortB.2              ' Invert the state of the pin
 
 
    Case 2                          ' It was Phase 1 that rolled over
        TOGGLE PortC.1              ' Invert the state of the pin
        TOGGLE PortC.2              ' Invert the state of the pin
 
    END SELECT
 
RETURN

Again, it compiles but I've not tested. One concern I have is the time between the two outputs for each halfbridge switching but since the dutycycle is effectively zero at the time of switching there should be no risk of shoot-thru etc. This of course also depends on the design of the hardware which I haven't seen so I'm just raising a warning about it.

/Henrik.