Summary

Make thePin.irq() wakeup behaviour more consistent on rp2.Closes#7035 and partial fix for#16180

Goal is that any pin which hasPin.irq() and atrigger set will wake rp2 port from anymachine.lightsleep() call.

Details

Currently:

• A Pin with an irq() trigger is a wakeup source only whenmachine.lightsleep(n) is used with a timeout, and only if an IRQ handler is set.

After this PR:

• A Pin with an irq() trigger is a wakeup source from both indefinitemachine.lightsleep() andmachine.lightsleep(n) with a timeout.

• A Pin with an irq() trigger is a wakeup source even if no handler function is set.

TODOs

• Waking RP2040 repeatedly frommachine.lightsleep() with no timeout and USB causes the USB connection to misbehave and eventually the CPU hangs. This is the same thing fixed for lightsleep with a timeout inrp2: Selectively leave the USB clocks enabled in light sleep. #15111 andrp2: Fix USB PLL glitch during wake from light sleep. #15301 . However, with no timeout argument the RP2 goes to the lower power "DORMANT" mode so keeping USB clock running isn't an option. Callingtud_disconnect()/tud_connect() ortud_deinit()/tud_init() before and after going to dormant mode doesn't seem to be enough to fix this. One heavy-handed workaround would be to not select DORMANT if USB is enabled, just call WFI instead. However, then the wakeup conditions are a lot different which may be confusing if developing and testing via USB and then deploying...
• Test on RP2350. I have hardware coming, otherwise help is welcome.
• This implementation doesn't match the machine.Pin docs re: irq(wake=) argument. However, I think only cc3200 port has actually implemented this argument as documented, so the fix here might be to make the docs match the current reality rather than the other way around.

This work was funded through GitHub Sponsors.

Testing

• TBD

Trade-offs and Alternatives

• It seems likemachine.lightsleep() has had very limited utility until now (i.e. no possible wake source?) so maybe we should refactor to only use DORMANT mode for deep sleep where we don't have to worry about recovering the USB peripheral. Keeping clocks running does increase consumption, though.