MAX32600 User’s Guide
System Clock, Timers/Counters, Watchdog Timers and Real Time Clock
10.2 Watchdog Timers
10.2.1
Watchdog Timers Overview
The
MAX32600
features two Windowed Watchdog Timers (WWDT) that protect against corrupt or unreliable software, power faults, and other system-level problems
that may place the
MAX32600
into unsuitable operating states. When the application is working correctly, application software will periodically reset the watchdog
counter within a specific window of time. If the watchdog timer interrupt is enabled and the software does not reset the counter within the interrupt time period
(
), the watchdog timer will generate a watchdog timer interrupt. If the watchdog timer reset is enabled and the software does not reset the counter within
the reset time period (
), the watchdog timer will generate a system reset. In both cases, a watchdog timer interrupt or reset will also occur if the counter is
reset during the pre-window.
10.2.2
Clock Source Selection and Gating
The
MAX32600
supports multiple clock source selection options. This enables the use of both WWDTs to ensure that in the event a specific clock source fails, the
second WWDT will still catch the failure.
Each Watchdog Timer on the
MAX32600
supports clock source selection from one of three available clocks. To select the clock source, refer to the table below and
write to either the
or
field.
Note
See Watchdog Timer value explanation below.
Watchdog Source Selection
Clock Source
00b
System Clock (default)
01b
RTC oscillator
10b
24MHz ring oscillator
11b
Nano-ring oscillator
Once a clock source is set up for the watchdog timer, the clock must be turned on to the Watchdog Timer. By default, the clock is gated off to the block. To turn on
the clock and enable the Watchdog Timer Peripheral, write a 1 to the
register.
The default source of the watchdog timer is the system clock and is scalable via the
CLKMAN_CLK_CTRL_11_WDT0.watchdog0_clk_scale
and
CTRL_12_WDT1.watchdog1_clk_scale
registers.
Note
This does not start the watchdog operation, but enables the selected clock to clock the Watchdog Timer once the Timer is configured and firmware
enables the Watchdog. The
is below.
Rev.1.3 April 2015
Maxim Integrated
Page 555
