Hi Henrik,

Thank you once again for your very detailed response. Much appreciated.

I understand that my PID loop is running slow and appreciate that it would be best "to count the pulses in hardware instead of the COUNT command" BUT I need some direction on how to make this happen. I have had zero experience using timer interrupts (though I have worked with Darrel's DT-Interrupt for IOC). Can you walk me through the process or direct me to a previous thread which explains the process? I am really struggling to get my head around timer registers, where and how the pulses are stored and what needs to be done to retrieve them for implementation with the PID routine.

As far as the data outputting is concerned, I am quite happy to live with my "display on button press" routine just to see the filter gain terms after adjustment. I haven't played with a UART before so that will become a whole new learning curve for me. For the time being, I will be happy just to get the PID routine nice and stable. I can always program another PIC just to handle the RPM output routine...

Cheers
Barry
VK2XBP