As noted in discussion on PR #18263, the id parameter is optional on ports
that support virtual timers.
Add some more general explanation of hardware vs virtual timers, and remove
redundant documentation about timer callbacks in favour of the isr_rules
page.
This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>
Update the main machine.Timer specification, and any references to
hard/soft interrupts in port-specific documentation. There is a separate
copy of the machine.Timer documentation for the pyboard, so update that
too to keep everything consistent.
Signed-off-by: Chris Webb <chris@arachsys.com>
Latest versions of Sphinx (at least 3.1.0) do not need the `*` escaped and
will render the `\` in the output if it is there, so remove it.
Fixes issue #6209.
The WiPy machine.Timer class is very different to the esp8266 and esp32
implementations which are better candidates for a general Timer class. By
moving the WiPy Timer docs to a completely separate file, under a new name
machine.TimerWiPy, it gives a clean slate to define and write the docs for
a better, general machine.Timer class. This is with the aim of eventually
providing documentation that does not have conditional parts to it,
conditional on the port.
While the new docs are being defined it makes sense to keep the WiPy docs,
since they describe its behaviour. Once the new Timer behaviour is defined
the WiPy code can be changed to match it, and then the TimerWiPy docs would
be removed.
