P42 Pico M.2: A RPI Pico RP2040 board in new form factor.

RE: P42 Pico M.2: A RPI Pico RP2040 board in new form factor.

wolfgangfriedrich — Thu, 07 Nov 2024 02:53:57 GMT

As it happens too often, this revision 1 board has its issues. With my RadXA ROCK 3A SBC not arrived yet, I was going for the fly-wire test approach.

USB and power through an external 3.3 V regulator are working flawlessly. Power LEDs are on and the user LED is blinking away. Nice! UART on the m.2 and on GPIOs are doing simple loopback and the USB/UART is running a simple command line already.

Things that did not work out of the box: I2C (of course). I should pay more attention to the pin mapping. I cannot use I2C1 at the same time on the m.2 and the QWIIC connector. Also pin4 on the QWIIC is SCL, not SDA. Nothing a few cuts and wires cannot fix. Now I have a loop-back from the m.2 end to the QWIIC connector. One port is master, one is slave. Mint.
More wires will be required to test the uSD card, the SPI signals are connected up-sidedown to the SPI port on the RP2040. Pin mapping again! I blame this one on the schematic symbol, not showing all pin functions.

RE: P42 Pico M.2: A RPI Pico RP2040 board in new form factor.

wolfgangfriedrich — Thu, 15 Aug 2024 00:46:36 GMT

I managed to solder pin headers to the castellated holes, but only barely. Had to use a lot of hot glue to hold the header in place and still managed to rip off one pad .
Real holes would work much better, I give this idea a -1 out of 10. Would not recommend.
Even better is probably adding wires and have the pin headers somewhat strain-relieved from the 0.8mm PCB.

RE: P42 Pico M.2: A RPI Pico RP2040 board in new form factor.

shabaz — Sun, 11 Aug 2024 00:56:21 GMT

Hi Wolfgang,

Very interesting board! And great to see there's space for plenty of storage with the micro SD too!

Regarding castellated pins, I think it works on your board, because it's so small there are no through-hole pins. In that case, people can still use normal pin headers, and simply solder to the sides.

I recently saw a different module (not related to Pico) where they did a slightly similar thing, having castellated pads since they had no space for through-hole option, and then also containing a flat flex connector (instead of the edge connector since it wasn't an M.2 module), so that users could chose either option.

Nice idea with the 'poor-mans castellated connections', I can imagine for sure they will be very welcome when prototyping, even if they are slightly more difficult to solder to.