After the successful deployment in public transportation of 10 uRADMonitor A3 units, in the city of Cluj Napoca, it was clear that such field deployments need more flexibility in terms of connectivity if it was to cover more ground faster. So I designed a new PCB, version 102, to add just that.
The Ethernet module would be replaced by a Wifi ESP8266-ESP04 module in the uRADMonitor A3 Wifi variant, a SIM800L module for the GSM variant, and finally a RN2483 from Microchip in the LoraWAN variant. The last one is an exciting new direction, as it provides radio link of up to 15km with minimum power requirements. The sensors stay the same:
The joy was short, as soon after receiving the PCBs and doing the first tests, it was clear there were major issues:
1. the PM2.5 sensor received an upgrade in the factory, and the new units had a different footprint, incompatible with my PCB design
2. there is some kind of weird RF interference generated by the High voltage inverter inductor, affecting the 8MHz microcontroller crystal. This renders the unit unstable.
Oh well ... back to the drawing board.