robin7331
RP2040 pin 26 "Run" floating despite datasheet recommendation
Just debugging why our Pixel Pump only intermittently boots up despite seemingly all power being OK, and noticed that pin 26 on the RP2040 "RUN" is just tied to a test point "TP5", but not to a positive voltage rail as the RP2040 datasheet recommends at 2.12.5 "External Reset"; is there a reason for this being left floating?
Good catch! I somehow missed the fact that it should be tied high. I never ran into issues due to this.
Your particular device is working fine if you pull it high with a bodge wire between the TP and 3v3 ?
I did a bit of an investigation.
Its wild that the datasheet recommends to tie it high while the actual RP Pico and another example schemetic from the hardware design guide also just has a push button pulling it low on demand but letting it float otherwise.
We've not tried pulling it high. It's also been working pretty fine since yesterday, so who knows 😁 When I read about the pullup recommendation yesterday, I also read that the rpi dev boards leave also don't pull it up, and just have it exposed as a pin, so it's more likely that the internal pullup is sufficient.
I am starting to wonder if a PETG-CF base might have some weird properties about it though. Maybe odd capacitance with the board, or static build up.
Maybe its just a defective mainboard afterall. Give me a heads up if this continues to behave weird and I'll send you a new mainboard. ✌️