I see that the 'HC11 MPU has some sort of timer functionality, and I am wondering if and how I could use that functionality to emulate a MC6840 timer IC.
The 6840 timers in my projects are set up so:
Timer 1 - programmable delay; 1/16 second per count (the number of counts was preloaded before calling the subroutine). No external signals were associated with this timer.
Timer 2 - IRQ timer; set so that it provided a continuous 2439Hz signal. The waveform was then fed into the MPU's IRQ pin.
Timer 3 - carrier generator; set so that it provided a 12.5kHz signal, which could be enabled during transmit intervals. This also had an external output.
The 6840 timers in my projects are set up so:
Timer 1 - programmable delay; 1/16 second per count (the number of counts was preloaded before calling the subroutine). No external signals were associated with this timer.
Timer 2 - IRQ timer; set so that it provided a continuous 2439Hz signal. The waveform was then fed into the MPU's IRQ pin.
Timer 3 - carrier generator; set so that it provided a 12.5kHz signal, which could be enabled during transmit intervals. This also had an external output.