An STM32-based datalogger for electricity meters with pulse LED.

This repository contains both the PCB design files and firmware source code.

• detecting pulses of LED more than 100 mm away from the sensor,
• dynamic adjustment of bright / dark threshold,
• logging over one year of 1 minute resolution data to SPI flash,
• command line interface for debugging and reading logged data over USB CDC,
• support for RS485 communication.

I milled the single sided PCB on my CNC machine.

Some notes:

• The DCF-3850N connector is only there for future-proofing. I don't currently use it and never tested it.
• The onewire bus connector is currently unused, but it should be easy enough to add DS18B20 temperature sensors.
• DS3231 RTC is necessary because the internal RTC on my STM32F103 was not accurate enough. Cut JP1 (battery power to STM32 VBAT) if you decide to use it too.
• The micro USB connector was a bad idea. I ended up replacing it with wires soldered directly to the board after accidentally breaking it off several times.

make help  # show available commands
make  # build
make check  # run cppcheck

For uploading to the STM32 via STlink, I use tools/mkbin and tools/upload_latest.