Design Review of nRF52840 Keyboard

[David Colburn]

Hello,

Recently I designed a wireless keyboard with a nRF52840 as the main processor. I had the board reviewed by a friend and had it produced by JLCPCB. I have assembled the board, but there is an issue that makes it so I am unable to connect to it with Bluetooth or SWD. I will attach the schematics and board design below. If anyone sees an issue that would make the board inoperable please let me know. For reference, the nPM1300 does work and I was able to confirm the voltages.

Thanks

[hmolesworth]

One issue lies in pin P0.06 receiving phantom power (aka back-drive) from RGB_POWER due to a schematic error. This will interfere with the nRF52840 reset mechanism as this pin will partially power the nRF52840 internal VDD from +5V/10K via the internal schottky clamp diode before the 3V3 external VDD rail rises.

Test by removing R9 and switching back on :-)

I should add this was only a quick review; if you would post a searchable pdf it would be easier to look further if required.