led pwm cycle

Comments

• JonnyMac Posts: 9,281

  2007-07-20 00:15 edited 2007-07-20 00:15

  Here's a simple bit of code:
  
  

  ' =========================================================================
    INTERRUPT 10_000
  ' =========================================================================
  
    INC pwmTimer
    IF pwmTimer = 0 THEN                          ' time for new cycle?
      acc0 = level0                               ' reset accumulator(s)
      Led0 = 0                                    ' clear PWM output(s)
    ENDIF
  
    INC acc0                                      ' update accumulator?
    IF acc0 = 0 THEN                              ' on rollover
      led0 = 1                                    '   activate output
    ENDIF
  
    RETURNINT
  

  
  
  
  You need a pwm timer (for any number of outputs); when this rolls over then you start the new PWM cycle. At the start you'll transfer the level for the pin(s) to the accumulator(s) for that(those) pins; the outputs are cleared at the same time. Then you increment the accumulator(s); when there is a rollover detected then the output is activated. In use, the larger the value of "level", the sooner the output will be activated within the cycle and the brighter the LED will be.
  
  Keep in mind that when you're using an ISR, instructions like PAUSE, SEROUT, etc. (anything timing based) is affected.
• Travis Best Posts: 8

  2007-07-20 13:05 edited 2007-07-20 13:05

  thanks I got it to work thanks for the help