@sebastian would you mind having a quick look at a KiCAD schematic and and PCB for me before I send it off for fab? It's just a few headers and a RPi pico but I need to be sure I've done it well enough.

@g7kse Sure. If you can somehow send me the files, I'd be happy to take a look.

@sebastian Great, really appreciate it. I've put them it a sort of github repo (not entirely sure i know what I'm doing) github.com/g7kse/CanSat/tree/m

@g7kse Not sure how you plan on mounting the BMP280, but to me the connector looks the wrong way round. You can plug it in 180° rotated, but then it might interfere with the LM7805 and its capacitors.

@g7kse I'm in a very boring remote meeting for work, so I figured I might do something productive.

The RFM9x looks okay, but you might want to check the GPS since I don't know which module you plan to use.

@sebastian will do, also on long teams meeting. really appreciate it. was sent one of these circuitspecialists.com/GPS-MOD

@g7kse Similar problem. The pins line up, but the image of the GPS module shows the bottom. So that socket is probably also rotated.

On the bright side, TXD is connected to RXD on the Pico and vice versa. (One of my all time favourite mistakes, is connecting TXD to TXD and RXD to RXD.)

@sebastian theres a bit of a theme here. I need to take more care on placement and checking pins 🙂

@g7kse I've been designing PCBs for about 10 years now and I still print the layout on paper in 1:1 scale (making sure nothing is mirrored) to put the parts onto it for sanity checks.

Looking at the schematic I'd also add a diode between the screw terminal and the 7805 for reverse polarity protection. Since you are not using low drop I'd assume you can spare the 0.7v drop over the diode. Just in case somebody is in a hurry while connecting the battery.

@g7kse Some small cosmetic things:
Theres a ground trace in the upper left corner, that runs outside the copper pour.

Also I'd move the RST track further away from the pads. If you solder the pico directly to the board, you might end up scratching the silkscreen and shorting the trace to a pad. Tiny risk, but there's space, so it won't hurt to move the trace.

@g7kse Usually I just delete all the ground traces that will run inside a copper pour. Makes things looking a little cleaner in the PCB editor, but you have to be little more careful not to end up with disconnected "islands".

Follow

@g7kse There are a few traces that I'd route a little different, but that's mostly personal preference and it shouldn't make difference functionally.

Other than that it's neat little board.

· · Web · 1 · 0 · 0

@sebastian brilliant. Thanks. I didn't really want vias but no big deal. If I can explain this well enough to a teacher then I will tackle the condensed board with a minimal rp2040, lora, bmp280 and GPS without needing breakouts

Sign in to participate in the conversation
chaos.social

chaos.social – a Fediverse instance for & by the Chaos community