I have started gathering pieces for a bus sign prototype, and for the radio base station that will be needed to send updates to them over the air. Here you see a pair of microchip modules that each include RISC processors as well as LoRA and WiFi radios, plus antennas for both kinds of radio
Installed bus signs will use rubber-duck style antennas as seen here but the base station will probably get a bigger antenna to help the signs work reliably at longer distances — at 915 MHz a full-wave antenna is around 13″ long. Expected practical range is somewhere between 1-3 km in our urban environment
The other components in this image are a small solar panel (black), as 4.2″ e-ink display (white), and the small black rectangles are 2.4 GHz antennas. The deployed bus signs won’t use WiFi, but I will use it during development and I think there will be a way to enable Bluetooth for maintenance and updates — I want to be able to apply software changes after signs are installed at bus stops, ideally without dismounting them
The compute and radio module I’m using is a bare-bones device. It needs other components to regulate power, to manage a battery, to connect to solar power, to drive the display, and to connect to USB/UART for programming. Here you can see a hand-assembled version of some of that chain, which is enough to get the prototype powered up and connected to both radios. This chain does not yet include the components needed for solar or e-ink
For the deployed version I will want a custom PCB, both the make the device both more compact and easier to assemble. I have already spent some time drawing up schematics for that PCB and I hope to do the board layout and have a sample manufactured in the next few weeks
