Opening Station Control left the compass blank for a second or two while the
amplifiers, relay boards and power supply filled at once.
Nothing was slow. The status bar keeps the shared heading loop running, so when
the compass mounts there is already a tick pending — up to the full three-second
idle interval away — and the new subscriber simply waited out the rest of it.
The heading was known the whole time and had nowhere to be read from.
The last heading is now kept and handed to whoever subscribes next. That matters
more on the Alpha SPID this was reported on than it would elsewhere: every poll
is an open, a read at 600 baud and a close, so even fetching immediately on
mount would not have been immediate.
In a microtask, so a subscriber is never called back before subscribeRotorHeading
has returned to it.
rouggy
e5c9ca1a7d