I was close to buy a Fibaro complete set until I discovered MySensors Project. This project is really cool, I'd like to thanks everyone involved in it. I'm more an hardware guy, so I wanted to do a little sensor board that I can spin for 10 units or something like that to cover the needs of my apartment.
I decided to design a little sensorboard that fit on the back of a 2AA holder ( 58*33mm) that can fit all the sensors I would need. The idea is that once you have the PCB, you solder just what you need on it. But it can work with every sensors populated also.
After days of reading and comparing sensors / supplies solutions, these are the specifications I choose:
- Works on two AA batteries in series. Use an MCP16252 to generate 3.3V that is enabled by default but can be switched off (and so bypassed) by the MCU if the batteries voltage is enough.
- Battery voltage monitored by the MCU
- Arduino compatible atmega328p design. External 512k spi flash for future OTA
- RFM69HCW design. It seems this is better for range and overall reliability ?
- PIR sensor: Custom design with the E931.96
- Light sensor: TSL2591
- Temp/Humidity sensor: Can use SI7020, HTU21D, and SHT2x range from sensirion
- Pressure sensor: BMP280
- IMU: MPU6050, MPU9255
- Two RGBW 5050 LEDs
- Extension connectors that can be used to stack extension board on top of the PCB.
I estimated it could achieve 1 to 3 years of battery life. I try to implement every hardware energy saving possibilities (hardware interrupts, ...).
Have you any advice or comments on this ? I have zero experience with MySensors and these sensors, so that could help. Here is a preview of the PCB : (routing still in progress). If anyone would like to see the schematics, I just need to clean it to release. This will be open source hardware if anyone is interested.