watchdog: support catching the timeout

With this patch, the exception can now be caught:

    import microcontroller
    import watchdog
    import time

    wdt = microcontroller.watchdog
    wdt.timeout = 5

    while True:
        wdt.mode = watchdog.WatchDogMode.RAISE
        print("Starting loop -- should exit after five seconds")
        try:
            while True:
                time.sleep(10)
                # pass # This also works for a spinloop
        except watchdog.WatchDogTimeout as e:
            print("Watchdog Expired (PASS)")
        except Exception as e:
            print("Other exception (FAIL)")
    print("Exited loop")

This prints:

    Starting loop -- should exit after five seconds
    Watchdog Expired (PASS)
    Starting loop -- should exit after five seconds
    Watchdog Expired (PASS)
    Starting loop -- should exit after five seconds
    Watchdog Expired (PASS)

Signed-off-by: Sean Cross <[email protected]>

Author: xobs

shared-bindings/watchdog/__init__.c

@@ -74,6 +74,7 @@ mp_obj_exception_t mp_watchdog_timeout_exception = {
 STATIC const mp_rom_map_elem_t watchdog_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_watchdog) },
     { MP_ROM_QSTR(MP_QSTR_WatchDogMode),   MP_ROM_PTR(&watchdog_watchdogmode_type) },
+    { MP_ROM_QSTR(MP_QSTR_WatchDogTimeout),   MP_ROM_PTR(&mp_type_WatchDogTimeout) },
 };
 
 STATIC MP_DEFINE_CONST_DICT(watchdog_module_globals, watchdog_module_globals_table);