51422 Watchdog timer - reset

[roger hayes]

What's the trick to using the WDT without causing a system reset??? We want to use the WDT for a pause mechanism - then continue from the pause at the same Main location? tks!

[John Kelley]

'm not sure what you're trying to use the WDT for. WDT is typically used to effect a CPU reset in case your code freezes or deadlocks.

Typical usage is:

• set CONFIG to (WDT_CONFIG_SLEEP_Pause << WDT_CONFIG_SLEEP_Pos) (see nrf51_bitfields.h for more options)
• set the CRV register to 32768 * number of seconds to wait before CPU reset
• set RREN to WDT_RREN_RR0_Msk
• set TASKS_START to 1
• set RR[0] to WDT_RR_RR_Reload on every loop of your main loop (and also any long running subroutine) to prevent WDT from triggering

[Ole Morten]

Correct. Also, if you get a timeout event, there will always be a reset. What you want is therefore not possible. Take a look at section 19.1.3 in the nRF51 Reference Manual for details on how this works.