Principles
- Use a MAX44009 to measure environment light
- Use an Arduino Pro Mini 3V3 modified to be battery supplied
- The Arduino 3.3V 8mhz can handle down to roughly 2.8V and the Nrf24l01+ down to 1.9V. Hence the batteries can not be NiMH rechargeables - Alkaline or Lithium required. We use a CR2032 coin cell which gives 3.3V.
- Possible later improvement: Program the BOD to 0xFE = 1.8V.
- Prepare the Arduino Pro Mini for use with a battery supply: remove the power LED, remove the voltage regulator.
- Prepare the MAX44009 module to be supplied by 3V.
The result
Used Components
- NRF24L01+SMD
- ArduinoProMini3V modified to reduce current consumption for battery supply
- AdapterProMiniForNrfSmd Connects the NRF24L01+ with the Arduino
- MAX44009-Light-Sensor 3V version
Wiring
| Component | Pin | Wire/Component | Pin | Component |
|---|---|---|---|---|
| ArduinoProMini3V | VCC | red | plus | Battery CR2032 |
| ArduinoProMini3V | GND | black | min | Battery CR2032 |
| AdapterProMiniForNrfSmd | IRQ | green | D2 | ArduinoProMini3V |
| MAX44009-Light-Sensor | VCC | red | VCC | ArduinoProMini3V |
| MAX44009-Light-Sensor | GND | black | GND | ArduinoProMini3V |
| MAX44009-Light-Sensor | SCL | A5 | Purple | ArduinoProMini3V |
| MAX44009-Light-Sensor | SDA | A4 | Green | ArduinoProMini3V |
| NRF24L01+SMD | IRQ | Blue | D2 | ArduinoProMini3V |
Programming
- Select as board: Arduino Pro or Pro Mini
- Processor: ATmega328P (3.3V, 8MHz)
- Serial monitor: 19200 Baud
- Use platformio
Code at: LightSensor.ino
I2C scanner
The I2C scanner software gives:
Scanning... I2C device found at address 0x4A ! done
First sign of life
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