Awesome
DCF77 transmitter for Raspberry Pi Pico W
Overview
This project is DCF77 transmitter for Raspberry Pi Pico W in proximate usage
This project supports:
- fetch CET (CEST) time by NTP
- DCF77 carrier frequency at 77500 Hz
- DCF77 amplitude modulation (High: 100%, Low: 12.5%)
- DCF77 phase modulation (0°, +15.6°, -15.6°) (Implemented, not verified yet)
- minimum peripheral circuits with wired headphones to emit weak radio waves
Supported Board
- Raspberry Pi Pico W
Pin Assignment
| Pico Pin # | Pin Name | Function | Note |
|---|---|---|---|
| 4 | GP2 | PIN_MOD_P | DCF77 signal differential output Pch |
| 5 | GP3 | PIN_MOD_N | DCF77 signal differential output Nch |
- Single-ended signal is not available since pair signals are asymmetrically driven in actual to have effect of PWM. Use a transformer to convert into single-ended output.
Connection Diagram
How to make the program work
- Use Thonny (Confirmed with Thonny 4.0.2, Python 3.10.9)
- Install MicroPython (Raspberry Pi Pico) interpreter firmware on Raspberry Pi Pico W by Thonny
- Confirmed with MicroPython v1.22.2
- Add
secrets.pyto include your WiFi configuration and put it on the storage of Raspberry Pi Pico W
# secrets.py
secrets = {
'ssid': 'xxxx',
'password': 'xxxx',
}
- Excecute
pico_dcf77_tx.pyfrom Thonny - For stand-alone application, please rename
pico_dcf77_tx.pyasmain.pyand store in the storage of Raspberry Pi Pico W
Log
Bit description log displayed in the console is made compliant to https://www.dcf77logs.de/live except for Civil warning bits / weather information
Timecode: Sat, Jun 03, 2023 21:17:00 0-000000000000000-001001-11101000-1000010-110000-011-01100-110001001
Tips for emitting DCF77
- The recommended way to make the clock detect DCF77 emulated singal in limited proximate environment, is just to connect wired earphone between PIN_MOD_P and PIN_MOD_N pins through designated circuit (LPF) and put the clock close to the earphone cable. (This could damage the earphone. please try with cheaper one.)
