Imported from GitHub: Cath272/ESP32-Low-Power-Temp-Monitor · commit 541edd1 · license GPL-3.0
Description
Introduction ESP32 Low Power Temp Monitor is an ESP32 C6 based low power Temperature and Humidity Monitor that aims to have a device that is very efficent and doen't need charging. General description The device reads the temperature, relative humidity and...
README
ESP32 Low Power Temp Monitor
Introduction
ESP32 Low Power Temp Monitor is an ESP32 C6 based low power Temperature and Humidity Monitor that aims to have a device that is very efficent and doen't need charging.
General description
The device reads the temperature, relative humidity and barometric pressure and displays it on an 4.2 inch Epaper Display, alonside the current date and time. The device is awake just for a few seconds as it reads the tempereature and displays it and then goes to sleep. It performs a reading every minute. One a day it connects to WiFi and checks the current time to sync up with an NTP server to account for Daylight saving time and potential drifts in the internal esp32 real time clock.
In the project files you may find ESP32-C3 instead of ESP32-C6. I named it wrong when i created the project. The issue is just the file names, the footprints are correct and use a C6. The TPL5111 is currenly does not work properly so i emulated it in software using the esp32 deep sleep.
Block diagram
Hardware Design
ESP32 C6 Wroom 1 Module
This project is based around a ESP32 C6 Wroom 1 Module that incorporates a RISC-V single-core microprocessor with 4MB of flash, WiFi 6 and Zigbee
TPS63020
The TPS63020 is High Efficiency Single Inductor Buck-Boost Converter, used for converting the 5v from usb or the Li-ion battery voltage(3.0v to 4.2v) to a very stable 3.3V for the Microcontroller and the epaper display. The main advantage of this ic is its low operating quiescent current: 25 μA; and it's low cost:0.55€
BME280
The BME280 is a digital humidity, pressure and temperature sensor.
4.2 Inch Epaper Display
GDEY042Z98 Tri color (Black, White and Red) Epaper display using a SSD1683 driver chip, the main benefit of this display is its big size (4.2 inch) and very good price for an Epaper display (around 10€) datasheet
TPL5111
The TPL5111 is a Nano Power System timer for power gating. It is used to turn on the esp32 every minute to read the temperature
MCP7381
The MCP7381 is an integrated Li-ion cell battery controller
Li-ion 250MAh battery
Small 250Mah generic Li-ion cell with protection, used because of its small size
Solar Panel
Generic 1W 5V Solar panel
Schematic
Bill of Materials
| Component | Image | Model | Pcs | Price |
|---|---|---|---|---|
| ESP32-C6-WROOM-1-N8 |  | ESP32-C6-WROOM-1-N8 | 1 | € 4.91 |
| Buck Boost Coverter | TPS63020 | 1 | € 0.52 | |
| TPL5111 |  | TPL5111 | 1 | € 0.47 |
| BME280 |  | BME280 | 1 | € 2.78 |
| MCP7381 |  | MCP7381 | 1 | € 0.84 |
| Solar Panel |  | 5V 1W Solar Panel | 1 | € 2.23 |
| 4.2 Inch Epaper Display |  | GDEY042Z98 | 1 | € 11.64 |
PCB
Case and 3d design
The case was make using autocad and exported to stl The stl files can be found in the 3D Parts folder
The gerber production zip file can be found in the Production folder
Software Design
The device wakes up, connect to wifi on the first boot, reads the time from an NTP server, and then for the next 24 hours it just reads the temperature and displays it. The time is kept in a register while the esp sleeps and increments it on every boot. Every 24 hours it connect to Wifi to check the time again for accuracy. The program can be found in the Project_Code folder
Display
The program is based around the GxEPD2 libary for interfacing with the Epaper display,
Fonts
The font used in this project is Roboto with 2 diffrent font sizes: 16pt for the time, date, altitude and barometric pressure and 48pt for the Temeprature and relative humidity The font were converted from True Type to Adafruit's GFX Font format (also used by GxEPD2 as it is based on Adafruit GFX) using the ttf2gfx utility
BME280
Adafruit_BME280 for the BME280 sensor
Time
For time i used 4 libraries:
- esp_timer (esp_idf library) to get the execution time of the code
- ESP32Time for keeeping the time and displaying it in a C style format on the display
- ezTime for getting the time from an NTP server, the time is region based in this library and i used it to avoid the problem of keeping track of daylight savings
Results
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