grauzone has created an ATTNode v3 addon board for the MH-Z19C CO2 Sensor. The addon has an onboard 3,3V voltage regulator to supply the node while providing the needed 5V to the sensor (directly from a 5V supply). It also incorporates 2 WS2812B RGB LEDs to signal current LoRa status as well as the current CO2 Level. Details on the hardware can be found on Github . While adding the code for the CO2-Sensors I also extended the firmware to support multiple sensors.
grauzone has developed a simple voltage regulator board to make more power sources usable for the ATTNode: Overview This is an add-on for the ATTNode to supply it with operating voltages between 3.5-16V. The voltage source must provide at least 120 mA. The PCB has the format of the CR2032 battery clip and is soldered to the back of the node instead of the clip. This allows the node to be powered by a USB power supply, a LiPo or any other fixed voltage power supply.