ble_sensor

Bluetooth Low Energy Sensor with Adafruit ItsyBitsy nRF52840 and BME280 module

Experiments to optimize power consumption.

Run 1: Indirect current measurement BLE module with sensor module

• Adafruit ItsyBitsy nRF52840 Express development board
• BME280 temperature, humidity and pressure sensor via I2C
• Measurement interval: 60s
• Power supply: LiFePO4 battery in AA-Format with 550 mAh, fully charged

Start time: 05.01.2022, 21:39
measured battery level: 70%

Stop time: 14.01.2022, 01:14
measured battery level: 10 %

Runtime: 171 h, 35 min (ca. 7 days)
Estimated current consumption: 3 mA
(500 mAh / 171,5h = 2,9 mA)

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Run 2: Indirect current measurement BLE module without sensor module

• Measurement interval: 60s
• Power supply: LiFePO4 battery in AA-Format with 550 mAh, fully charged

Start time: 22.01.2022, 15:15
measured battery level: 70%

stopped after 170h (ca. 7 days)
measured battery level: 68 %

The i2c bus and the sensor board seem to be the power hungry culprits

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Run 3: Indirect current measurement BLE module with sensor module

• I2C sensor is powered via GPIO pin and switched off during sleep/delay
• Measurement interval: 30s
• Power supply: LiFePO4 battery in AA-Format with 550 mAh, fully charged

Start time: 06.02.2022, 10:30
measured battery level: 70%

Stop time: 20.02.2022, 21:30
measured battery level: 10%

Runtime: 347 h (ca. 14 days)
Estimated current consumption: 1,4 mA

(500 mAh / 347h = 1,4 mA)

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Run 4: Indirect current measurement BLE module with sensor module

• I2C sensor is powered via GPIO pin and switched off during sleep/delay
• Measurement interval: 30s
• Power supply: LiFePO4 battery in AA-Format with 550 mAh, fully charged
• Dotstar LED removed from board

Start time: 21.02.2022, 17:00
measured battery level: 72%