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DCF77 Monitor, rx module, pic16, LCD Display, serial output

DCF77 Monitor, RX module, PIC16, LCD, Serial output

Here bit52 is 200mS long

Here bit48 is 92mS long, the 005 means that the last 5 recieved minutes was with perfect checksum

I used a good old test kit I had handy, it contained a 2402 LCD display and a PIC on a PCB
it is the same PCB as I used in my homemade wattmeter project
I have made the software so a cheap 1602 display can be used for the monitoring.

Purpose / Idea

The use of this DCF77 reciever and monitor is a standalone unit that can set my Nixie clocks via serial commands
this unit can be used to set whatever type of clock, that accecpt the serial string, but it can also be used alone to monitor the DCF77 signals,
however this is not a clock, and if no DCF77 signal is present or if noise is too strong, the time is unreadable,
THIS IS A MONITOR with serial output not a clock, OK.
if no display is mounted a few LED will indicate signal quality and ok data.
12 years ago I made my own DCF77 reciever using resonant coils and transistor amplifiers,
today a little smart and cheap Conrad module can perform even better due to crystal filter with super narrow bandwidth.

Parts used:
Conrad DCF77 RX module BN 641138
10K pull up from pin4 output to pin2 power, pin1 is ground.
1uF decoubling on the DCF77 digital data, helped.
PIC16F876 at 4MHz and a 1602 standard LCD display.
The DCF77 decoding is straight forward, but I have added some extra security,
The serial set string will be transmitted if 3 (or maybe 5) following minutes are with perfect checksum,
and their minutes are in sequence, while all other data are stable, this will prevent crap data to screw up the time on my loved nixie clocks.

Video clips

dcf77-2402-rxbits.avi first I used all avail 24 chars.
note how the mins and hr bits are recieved and displayed while this happens.
dcf77-1602-rx.avi I think a 1602 is good and cheap, so lets use that
note on both videos the short bit0 and the long bit1 are close to 100mS and 200mS, this means good signal.

Schematic : Later

Software : Later

This is still under development, so hang on.

Okt. 2004.