66 MSF Clock

66 : MSF Clock

Select Project123456789ONSW2
  • Author: Jamie Wood & Daniel Cannell
  • Description: MSF radio clock
  • GitHub repository
  • Clock: 12500 Hz

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.

IO

#InputOutput
0clockshift_clk
1resetshift_data
2datashift_latch
3inverted
4shift_date
5
6
7