ESP SOLAR CHARGER Logger

A device that logs the solar panel output, playing with freertos while building a small tool

Current development status

SPIKE-ing

Motivation

Logging the voltage and current output/input on the solar and the battery ends, requires a lot of manual work, using traditional methods like a regular multimeter. So I started to build a dual chanel multimeter for voltage and current that, stores at a certain tick the readings.

Because wifi/ble MCUs come in cheap these days and they provide an simple way of logging data, I strongly consider implementing at least one of the two remote interface : either BLE and MQTT.

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Prototypes modules

• 1 x TTGO ESP32 Battery - a development board with an ESP32, a sd card slot, a battery charger and a joystick
• 2 x INA219 Module - a current and voltage sensor
• 1 x a real time clock

Considering implementing

• BLE Interface
• TCP (MQTT) Interface

Lessons Learned

1. Wire lib is not working in tasks with low priority. because of #2.
2. CPP variables don't outlive the block scopes; that is why setup has a while(true) {noop();} at the end
3. QueueHandle_t is a pointer already, no nead to convert it to a pointer
4. Downside of INA219 is that you must connect a common ground with the MCU to measure the voltage (Hope I'm wrong)