[time-nuts] Time Code generator

[jimlux]

Jeroen Bastemeijer - EWI wrote:
> Dear time-nuts,
> 
> A PIC based IRIG timecode generator sounds very interesting! Would like to build a new stand-alone IRIG-timecode generator since my Brandywine died....
> 
> Did some Google-searches without succes.... unfortunately! :-(
>

The generator is easy..
counting time in bcd is just arithmetic, then
you generate a bit stream, which is 100 bits long, and clock it out. 
The "symbols" in the bit stream are either 0.2, 0.5, or 0.8 long (that 
is, 2,5, or 8 milliseconds.

  all you have to do is generate 1kHz and amplitude modulate it somehow 
(I suspect that 2 resistors would do very nicely)

You could set up a 2kHz real time interrupt and toggle the output on 
each RTI.  count every other cycle to count the milliseconds and deal 
with clocking out the symbols/bits

Depending on how you want to do it, you can generate the symbols on the 
fly or just build up 1000 bits (1 per millisecond) and clock them out. 
Depends on how much RAM you've got, really.