ATX power on Duet 3 mini 5+

[tomasf]

I just upgraded from Duet Wifi with RRF 2 to Duet 3 mini 5+ with RRF 3.2.2 and SBC. It's an awesome system, and I especially like the object model. I have a few questions about ATX power:

1. On Duet Wifi, PS_ON was off (high) by default, so the board started with power off. On the 3mini, it seems to be on by default (low)? If I put an M81 into config.g, the power is briefly on and then turns off.
   I'm using a pull-up resistor to make sure that a floating state is interpreted as off, so that shouldn't be the problem. Am I doing something wrong or is this the intended behavior?

2. The state.atxPower entry in the object model seems to always be set to false, even when power has been turned on. The web UI reflects this; if I turn on power and reload the page, the switch is shown as off again. Is this a bug or something I've misconfigured?

Thanks!

[dc42]

1. On current revisions of Duet 3 Mini, the PS_ON output may turn on very briefly when you apply VIN or 5V power, before firmware initialisation turns it off. If this happens, you should be able to suppress it by connecting a resistor between IO4_OUT and ground (because PS_ON shares a microcontroller pin with IO4_OUT). A resistor value between 3.3K and 10K should work. Do not use pin IO4_OUT if you are using PS_ON.

2. You are correct, the PS_ON state is not correctly reported in the object model. I will fix this in the next 3.3beta release.

[tomasf]

@dc42 The pulldown resistor solved it. Brilliant, thank you.