To avoid inadvertent watchdog configuration
changes, the
TCAN284x-Q1 family implements a watchdog
configuration register locking and unlocking mechanism. Registers 8'h13, 8'h14, 8'16 and
8'h2D are only programmable in standby mode and are the registers that become locked.
These registers automatically lock with the first WD input trigger event or when
transitioning to normal mode via SPI command. The unlocking mechanism is transitioning
to standby mode; which allows one write to each of the four registers. If the registers
are locked while in standby mode, the device must transition to normal mode and then
back to standby mode. The WD can be enabled in sleep mode and is only capable of timeout
and the configuration registers are locked. See
Figure 1-1;which
shows the described behavior.