Adding an ENS161

[taliesin]

I'm looking into extending the functionality of some LYWSD03MMCs by:

• interfacing an ENS161
• replacing the CR2032 by 2 AA cells

to create a battery powered BLE air quality sensor, also delivering temperature and humidity.

The ENS161 supports a low power and an ultra low power mode. I calculated battery life from the consumption specified in the datasheet and get about 10 month for the low power mode and about 2 years for ultra low power.
The power consumption of the chip during measurement is about 12mA, the cycle times are 1 minute and 5 minutes respectively.

While the implementation of the driver seems easy enough, I wonder about the power cycling. I read somewhere that I²C is not well behaved during wake-up cycles, this might cause trouble as the sensor needs to stay in the correct mode to deliver precise measurements.

Are there other things to watch out for?

[pvvx]

TB_ENS160_vNN.bin

TB_SCD41_vNNn.bin

SCD41

Measurement 30 sec - 3.4mA

Mmeasurement 5 sec - 17.5mA

---

[pvvx]

The power consumption of the chip during measurement is about 12mA,

45 mA 5 ms

the cycle times are 1 minute and 5 minutes respectively.

In normal mode, these chips measure the weather on Mars, not CO2.
In LowPower mode, they measure something completely unknown.

[taliesin]

Thanks for your response, Victor.

Have you been testing the ENS161 version? I was inspired by https://github.com/StuckAtPrototype/AirCube
The results seem pretty OK to me. Clearly one can't expect a CO2 level measurement from a VOC sensor and I'm really more interested in an air-quality indication and 5 levels would be OK for my application.

For the LED color he's using register 0x26, which is a relative indication of the last 24h.
But I'll take your advice and pretest on different platform (like ESP or Raspberry) to get a quicker shot on the sensor values.

[pvvx]

Count =

Bluetooth-Devices/bthome-ble#209

---

In addition, the specified firmware controls the DAC for ventilation in user-specified ratios.

[taliesin]

Yes, that was exactly what I was thinking of. The AirCube delivered a pretty nice chart (eCO2) as-well, maybe the ENS161 works better than the ENS160, we'll see.