To avoid inadvertent watchdog configuration
changes, the
TCAN1576-Q1 implements a mechanism for locking and unlocking watchdog
configuration registers. This impacts registers 8'h13, 8'h14, 8'h16 and 8'h2D. These
registers can only be programmed in standby mode. The WD trigger write to 8'h15
automatically locks these registers. Once these registers are locked, an SPI write to
them is treated as a WD failure. To unlock these registers, the device must transition
into standby mode from normal or listen mode (see
Figure 8-28). Unlocking is good for one write to each of the registers.
Note: (1) Registers 8'h13, 8'h14,
8'h16, and 8'h2D are allowed one write each after entering standby mode before being
relocked.