Almost decent scale

Work in progress, a clone of decent scale for home use

BOM:

• ESP32 or ESP32s3
• HX711
• Load cell

Calibrating over Bluetooth:

The scale supports calibrating over bluetooth. To calibrate the scale, send the 0x03F1 command to 36F5 which will activate the calibration mode.

Once in calibration, the process is the same as when calibrating over Serial port.

• remove all weights and wait for the scale to tare (7 seconds)
• add a known weight
• read the value from the weight characteristic FFF4
• calculate the factor: (units_read_from_char / known_weight)
• write 0x03F2XXXXXXXX to 36F5 where XX is the uint32 representation of the factor multiplied by 1000
• scale should be calibrated now

TODO:

• conform to DE scale BT protocol (tare, led, version, etc) ✔️ looks ok
• Add own thread logic
• Calibration over BT ✔️
• DE1 tare command handling ✔️
• esp32-s3 target ✔️
• (maybe) web server
• esp32-s2 mini target <- cancelled, only has wifi, maybe one day s3-mini

Use platformio.ini to define pins for your setup. Also if you want to use fake BT for some reason, add -D BT_COMMS_FAKE, otherwise use -D BT_COMMS_NIMBLE.

Additionally, I had to slow down my esp32s3 devboard - use -D ESP32S3_SLOWDOWN to reduce clock speed to 80MHz.