In trying to find a suitable power supply for the P2 I have come across an undocumented funny. If the WKP pin is pulled high, at power on this appears to stop the P2 starting up even though no pinMode or attachinterrupt has been made to this pin. Is there a rationale explanation for this?
Pin D10, pin 30? That should not occur.
There are several pins including D8, which is WKP on the Argon and Boron, that are boot mode pins that can prevent the device from booting, though they are active low, not active high.
I tried connecting D10 on the Photon 2 to 3V3 and it booted fine. Also GND.
This is a P2 on a custom board not a Photon2 which I have tried before. If I take away the pull-up resistor on this pin then it works fine. So maybe something else?
It's almost certainly something else, but not clear what.
Since the Photon 2 has a P2 on it, it should behave the same, but I tested again with a P2 D10 pin connected to 3V3 and it also booted as it should.
Thank you for trying it out and replying quickly. We are having a ton of issues with the peripherals around the P2 since the P2 is so sensitive on the 3V3 rail - it could be that.
It would not surprise me if a slightly slow slew rate on 3V3 caused weird behavior like that. The Photon 2 includes a supervisory reset circuit that prevents problems like that.
The P2 test board I used did not have a supervisory reset, but the P2 often works without it.
Hi Rick, I tried tying the D10/WKP pin on my P2 first board to 3V3 with a 10K resistor and to GND and without.
3V3 and no connection all work fine, 10K to GND works but I see D7 blue led flash and the RGB LED flash red/magenta quickly whilst getting there.
The custom board has no connection to WKP and it is still behaving weirdly - definitely when tied to GND it doesn't like it.
This is making a wake from hibernation when mains power restored feature way more complicated than it should be on paper (was with Photon/P1).