This embedded system measures temperature and humidity and outputs the data on an LCD. The BME280 sensor can also do pressure but I didn’t implement it because the MCU had no more space available. The whole project can be found here. I’ve also included datasheets for the MCU, sensor and LCD.
Development was done on FreeBSD using the workflow I describe here. If you’re using Microchip’s own tools, you’ll have to make some small changes to the code, but nothing too extreme.
Components
- Microchip PIC16F877A-I/P microcontroller.
- Adafruit BME280 temperature, humidity and pressure sensor.
- 16x2 LCD.
- 1x 16MHz crystal oscillator.
- 2x 10kΩ resistor.
- 2x 300Ω resistor.
- 1x 10kΩ potentiometer.
- 2x 22pF ceramic capacitor.
- 2x LED.
- 2x push-button.
- Breadboard and wires.
- 3x AAA batteries (4.5V total) or a 9V battery with a 5V voltage divider.
Safe temperature range
| Component | Operating temperature |
|---|---|
| PIC16F877A | -40°C - 85°C |
| BME280 | -40°C - 85°C |
| LCD | -20°C - 70°C |
So, it’s best for the system to operate in the -20°C to 70°C range.
Schematic
You can also get the PDF version.
