parasite

A low power soil moisture sensor based on the nRF52840.

TODO

• Figure out how to calibrate the ADC when running from different voltages, as the battery discharges
• Experiment with different TX power / battery tradeoff. Since we'll be deepsleeping most of the time, maybe we can get away with a lot of TX power.
• Implement deep sleep
• Measure current in deep sleep
• Measure current in operation (ADC + BLE adversiting)
• Test with a range of 2-5V input. Disconnect from USB and monitor using a serial post. Use the bench power supply to power Vcc with variable voltage. DO NOT CONNECT VCC FROM THE USB-TO-SERIAL BOARD!*
• Test with a coin cell
• Implement ADC for battery monitoring
• Figure out a way for people to configure the device with a custom name. Idea: BLE service (this is what my hacked xiaomi temp sensor does)
• Figure out how OTA works (if at all) over BLE
• Design new board using the nrf52 instead of esp32

Done

• Implement battery level monitoring
• Implement BLE advertising with moisture
• Implement ADC for the parasitic capacitor; check out air/water range (using protoboard)
• Simple PWM square wave generator
• Hook square wave generator to the protoboard sensor circuit
• Make the protoboard sensor work