The Jenny program consists of 2 parts, a LTC reader and a LTC generator joined together by a teeny bit of code that monitors  a push button every frame in TC read, if the button is held down for 25 consecutive frames it transfers from TC read , (storing the current incoming LTC of course) at bit80, the end of the current frame, and trundles over to the TCgen code in a microsecond or so, continuing from the LTC stored when the reader handed over to the Jenny.  It needs most of that microsecond to set up the numbers for the frame rate counter, figure out if DF or NDF standard, and look up the fiddle factors to compensate for any long term TCXO errors, from when the board was calibrated against my rubidium clock.

The TCreader has a lot of debugging code in it, like set a port pin high or low if something (defined by me) happens. I use the AVR’s PORTB for debugging, just convenient for the circuit board that I made.  The graphic LCD has it’s reset line connected to a PORTB pin, and somewhere in the TCreader this pin is being set low, unintentionally, so stopping the display, so not a faulty display, just me being untidy.

The TCgen has been running on the bench for a couple of weeks without dieing,

Happy, just got to get some enthusiasm to find the bug in the Reader part of the code.

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