I just noticed the other day that this thing existed; it supports 2.4 GHz wireless (not 5 GHz), and Bluetooth LE (BLE); the manufacturer part code is RMC20452T , also known as RM2 and it costs about $4.
Underside; the board is 16.5 x 14.5 mm in size (but you'll need some space for a ground plane):
The RM2 is useful for custom RP2040 or RP2350 projects where WLAN (again, annoyingly just 2.4 GHz)/BLE is needed; not useful for anything else as far as I'm aware. From a software perspective, coding should be no different to using a Pi Pico W.
The RM2 should be very easy to drop into KiCad projects, since the footprint/symbol/3D model is available.
The RM2 datasheet (PDF) seems easy enough to follow, but is extremely basic; and I found it a bit confusing regarding a 'reset' line it mentions, but the text is silent on that later. It is not clear what line that refers to.
There are no suggested layouts, the PDF just states a good ground plane is needed, and shows the copper fill keepout area.
Note that there isn't a version with antenna connector, however, one workaround would be to place the module on a PCB (large enough to have a ground plane, or perhaps use parts of an enclosure for that) and run the interface wires a short distance to the microcontroller, if you needed the antenna positioned somewhere not feasible on the main circuit board. Personally, if it were me, I would try to use the module in that way, i.e. on a separate PCB with short wires, before integrating onto a larger PCB; I'd much rather have it separately and position it for the best signal.
Anyone see a use for this module? Or if anyone has seen it in use, any photos showing how it was deployed in the design would be great to see.
At some point I'd like to experiment with creating a PCB for it, but I was wondering if anyone else had given it a shot, or were planning to, or would like to!
Thanks for reading.
