Microelectronics
Having recently setup a Home Assistant server (in getting ready to move home) I’ve been playing with ESPHome as a way to easily integrate my projects into the home.
With a view to make life a little easier for the next person I’ve included some sample config below which can be used with the Waveshare E-Paper ESP32 and ESP8266 Driver Boards (of note are the pin configurations and the platform type for the ESP32).
I’ve also found that as mentioned in the documents the 7.5″ v2 display really does require an ESP32 to drive it even if you’ve managed to get it working with other projects on the ESP8266. Additionally the ESPHome-Flasher tool delivers much more consistent results on an ESP32 when performing the initial flash.
In looking to keep occupied with the current pandemic going on I’ve taken my Microelectronics projects to a new level and have over the past few weeks kicked out a series of soil moisture sensors which are powered by battery (18650) with a small solar panel keeping them topped up.
As the battery charges/discharges the voltage changes and moves outside of the acceptable ranges for the little ESP32 MCU, here a load drop out voltage regulator like the Microchip MCP1700 comes into play by ensuring that the controller is fed the right voltage all the time. In researching this project I’ve come across a fair few articles which mention the regulator is only ‘stable’ or ‘the supply is smoothed out’ with a set of capacitors in line. Just to test that out I hooked my multimeter up to the MCP1700 without the capacitors and lone behold the wrong voltage is being kicked out. Put the capacitors in line and everything works as expected.
The article I followed when putting my final projects together is at these links:
- https://randomnerdtutorials.com/power-esp32-esp8266-solar-panels-battery-level-monitoring
- https://randomnerdtutorials.com/esp8266-voltage-regulator-lipo-and-li-ion-batteries
There does appear to be a discrepancy (1uF vs 100nF) between the capacity of the capacitors in the datasheet and the article (and indeed I’m having occasional issues with controllers resetting due to what appears to be a power problem) but for now things are working well enough.
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