66 MSF Clock

66 : MSF Clock

How it works

The MSF radio clock bitstream is synchronised, decoded, and the time displayed on an LED display driven by a shift-register.

How to test

  • Provide 12.5kHz clock to the clock pin, e.g. using the clock divider set to 0.
  • Connect the data input to a WWVB / MSF receiver module.
  • Connect the inverted input high if the module outputs a 1 when there is no carrier.
  • Connect the shift_date input to a button. If held, the display will show date instead of time.
  • Connect the shift register outputs to a 42-bit shift register chain. Bit 41 is shifted out first.
Bit Segment
41-35 Hours tens G-A (41=G, 35=A)
34-28 Hours ones G-A as above
27-21 Minutes tens G-A as above
20-14 Minutes ones G-A as above
13-7 Seconds tens G-A as above
6-0 Seconds ones G-A as above

Time and date are always both shifted out, so an 84-bit shift register will show both simultaneously.


# Input Output
0 clock shift_clk
1 reset shift_data
2 data shift_latch
3 inverted none
4 shift_date none
5 none none
6 none none
7 none none