The LIMP pin is for the limp home function
and is an open-drain, active low, output. The pin is used for a
limp home mode if the watchdog has timed out causing a reset.
The pin must be pulled up with an external resistor connected to
the battery supply, VSUP. For the LIMP pin to be turned off, the
watchdog error counter must reach zero from correct input
triggers. If programmed any event that triggers the fail-safe
mode also turns on the LIMP pin. The state of this pin can be
read back by setting DEVICE_CONFIG register 8'h1A[6] LIMP_RD_EN
to 1b. The state of the LIMP pin active (on) or inactive (off)
can be read back from LIMP_STATE at 8'h1A[5].