comair's Introduction

ComAir

A LoRa air quality sensor powered with an indoor solar pannel.

This PCB uses:

as MCU: STM32L412C8
for LoRa communication: RFM95
for energy harvesting: SPV1050
any 18650 lithium cell (could be recycled from old laptop battery)
as solar pannel, one or two: LL200-4.8-37
for CO2 sensing: SCD41
for temperature and humidity: either SCD41 or SHTC3

Warning this project is still work in progress, PCB may still contain errors.

PCB V1.0 preview:

TODO

Write some basic testing firmware
Evaluate energy balance
Optimize energy usage

License

CC-BY-SA

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comair's Issues

USB DFU bootloader blocked because of RFM95 module (DIO5)

There is no pull down resistor on RFM95 reset pin and DIO5 by default is clkout, this prevent the MCU to enter DFU mode generating a lot of:

[268721.923613] usb 5-3-port4: attempt power cycle
[268722.526763] usb 5-3.4: new full-speed USB device number 111 using xhci_hcd
[268722.526854] usb 5-3.4: Device not responding to setup address.
[268722.731529] usb 5-3.4: Device not responding to setup address.
[268722.938996] usb 5-3.4: device not accepting address 111, error -71
[268723.015776] usb 5-3.4: new full-speed USB device number 112 using xhci_hcd
[268723.015881] usb 5-3.4: Device not responding to setup address.
[268723.219173] usb 5-3.4: Device not responding to setup address.
[268723.426869] usb 5-3.4: device not accepting address 112, error -71
[268723.427205] usb 5-3-port4: unable to enumerate USB device

The simplest solution is to disconnect this pin which should be useless.

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