Air Quality Egg

Officially received my first Air Quality Egg shield in the mail last week, and been putting it through some paces with kind collaborators in Atmospheric Chemistry.

I’ve got a couple of shields and a couple of Nanodes, and have been remixing hardware, firmware, and testing environments. Notes on activities, links to more detailed write-ups, etc., go here.

Sensor Specs

Some extrapolations of manufacturer spec’d response curves for different sensors. See the links to Rpub (below) for more figures and details.

Chamber Testing

Coming soon.

Firmware

I’m on OSX and this worked for me:

  1. Download & install CrossPack for AVR® Development.
  2. Clone the aqe_sensor_interface_shield library from GitHub.
  3. If your shield is older, and has a Tiny48 instead of a Tiny88, splice the ATtiny48 configuration from this avrdude.conf into yours.
  4. Using an AVRISP mkII, flash the EEPROM, then the hex file.
    $ avrdude -p t88 -c avrisp2 -e -P usb -U eeprom:w:aqe_sensor_interface_shield.eep
    $ avrdude -p t88 -c avrisp2 -e -P usb -U flash:w:aqe_sensor_interface_shield.hex

I ran into a problem where I was getting 0 back as the measured value, and Ro=4294967295=0xFFFFFFFF. The solution was to run the PollEggBus_WriteTest sketch (it’s under File > Examples in Arduino when you have the EggBus library installed), after changing Line 7 to read:

uint32_t r0_values[2] = {2200, 750000};

That successfully set Ro back to what it should have been, and persisted through a subsequent upload of the PollEggBus sketch.

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