constants [[timerA-ctrl $fD5][timerA-val $fD6]]



to timed
    ;prescale value 1:2, bits 0-2 '000'
    clearbit 0 timerA-ctrl
    clearbit 1 timerA-ctrl
    clearbit 2 timerA-ctrl

    ;disable prescaler
    setbit   3 timerA-ctrl
  
    ;increment timer on rising edge
    clearbit 4 timerA-ctrl

    ;increment on external clock
    setbit   5 timerA-ctrl

    ;8-bit timer mode
    setbit   6 timerA-ctrl
   
    ;enable timer 0
    setbit   7 timerA-ctrl
    

    ; set the timer initially to 0 
    write timerA-val 0


   
    loop [
      ; repeat no-op 2990 times (should be changed to a more accurate
      ; timed value, probably by using the internal millisecond timer
      ; to wait a certain number of milliseconds, then report the micro-
      ; second timer value.  2990 is chosen as it produced the best 
      ; results in practice.
      repeat 2990 [no-op]


      ; send the timer value.              
      send (read timerA-val)
      

      ; reset the timer to 0
      write timerA-val 0
    ]
end