No Logo Tech NRF52840 controller boards

It turns out that ProMicro footprint clone of the Nice!Nano v2 controller with 21 GPIOs (which I bought for my Hesse Bluetooth keyboard) is part of a family of at least four similar boards of differing sizes, possibly all originally from No Logo Tech. In English at least, the naming is rather confusing! The others expose even more GPIO pins (although many not on easily reached pins), and some have an RGB LED built in too. Sadly most are rather lacking in documentation outside of product listings on AliExpress and the like, but they have LiPo battery charging, and are all using the Nordic NRF52840 chip so ought to work with ZMK for use in a keyboard design.

"ProMicro NRF52840"

"Nano 33 BLE NRF52840"

(Xiao-like) "SuperNRF52840"

"Super mini NRF52840" (with space)

The images of these controller boards are taken from AliExpress sales pages, cropped and in one case repositioned, but otherwise unedited.

"Promicro NRF52840"

The Promicro NRF52840 (Zepher supported) was originally launched as the "Supermini NRF52840" (not to be confused with the smaller board below which I assume was launched later).

Size: 17.78x33.00mm, 12 pins on left & right (13 including battery connections) GPIO: 21 as holes. Battery: Top two pins, by the USB. Summary: ProMicro footprint Nice!Nano v2 clone with slightly offset trio of middle pins. Battery and user single colour LEDs. No reset button. Price: ~£3 (AliExpress).

Arduino-like "Nano 33 BLE NRF52840"

Size: 17.78x43.18mm, 16 pins on left & right GPIOs: 22 as holes, plus 6 pads on back, plus 2 tiny thru-holes (30 in all). Battery: Top two pins, by the USB. Summary: Clone of the Arduino Nano 33 BLE, with battery charging. RGB LED. No reset button. Price: ~£13 (AliExpress).

Wee "Super mini NRF52840"

Size: 18.00x23.50mm, 9 pins on left & right. GPIO: 20 as holes, plus 8 pads on rear (28 in all). Battery: Pads on back. Summary: Bigger than a Xiao, but offers more easy to solder GPIOs. Battery and user LEDs. Reset button. Price: ~£10 (AliExpress; AliExpress).

Xiao-like "SuperNRF52840" aka "MINI NRF52840"

No Logo Tech's SuperNRF52840 repository has some documentation for this Xiao-footprint version - including images with their gear logo on the back (rather than the white stripe seen on AliExpress listings which are therefore likely of unoffical clones).

Size: 18x21mm. GPIOs: 11 as castellated holes, plus 9 pads on rear including NFC (20 in all). Battery: Pads on back. Summary: Xiao form factor, with different back pads. RGB LED. Reset button. Price:~£7.50 (AliExpress; AliExpress).

Conclusions

Pricewise, the "MINI NRF52840" has little advantage over the original Seeed Studio Xiao family, some of which also advertise 20 GPIOs. It does have an RGB LED though.

It would mean some fiddly soldering for back pad connections, but the "Nano 33 BLE NRF52840" or the new wee "Super mini NRF52840" (not the old one now called the "ProMicro NRF52840") should give me the 26 GPIOs needed for a Bluetooth version of my original keyboard design - the Gamma Omega TC36K (26 GPIOs for 36 keys diode free 6KRO with graph theory). Or, assuming the roll-over limitation of the Gamma Omega Hesse (21 GPIOs for 36 keys, diode free 4KRO with graph theory) doesn't bother me in practice, something with more keys...

Note that I have only tried one of the ProMicro NRF52840 clones at this point, and will soon be using it in my Gamma Omega Hesse keyboard.