nRF52: a single interrupt activation doesn't work

[perttierkkila]

TLDR: nRF52 blinky example doesn't work when serial is disabled.

Env

tinygo version 0.33.0 darwin/arm64 (using go version go1.22.5 and LLVM version 18.1.2)

This is a pretty wild bug which goes down to interrupt enable and this one line https://github.com/tinygo-org/tinygo/blob/release/src/runtime/runtime_nrf.go#L61

intr.Enable()

When this line is replaced code from Enable() with constant value, IRQ works properly. Only difference is internal irq.num is not used. Enabling any other IRQ doesn't do the trick.

arm.EnableIRQ(uint32(nrf.IRQ_RTC1))

And the weird part, if application enables ANY IRQ (for example IRQ num 240 which doesn't exist), IRQ_RTC1 starts working also. Due this, default settings with serial enabled, keeps IRQ_RTC1 working properly and hides a bug.

At least 0.31 worked properly as I have used serial=none setting a long time. Please keep older versions at brew to allow easily allow switching version. Now it is pretty PIA.