NXP Semiconductors
NHS3100
Temperature logger
NHS3100 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2018. All rights reserved.
Product data sheet Rev. 6.03 — 15 June 2018
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8.13 WatchDog Timer (WDT)
If the microcontroller enters an erroneous state, the purpose of the WatchDog Timer
(WDT) is to reset it within a reasonable amount of time.
When enabled, if the user program fails to feed (or reload) the WDT within a
predetermined amount of time, the WDT generates a system reset.
8.13.1 Features
• If not periodically reloaded, it internally resets the microcontroller
• Debug mode
• Enabled by software but requires a hardware reset or a WDT reset/interrupt to be
disabled
• If enabled, incorrect/incomplete feed sequence causes reset/interrupt
• Flag to indicate WDT reset
• Programmable 24-bit timer with internal prescaler
• Selectable time period from (TWDCLK × 256 × 4) to (TWDCLK × 2
24
× 4) in multiples
of TWDCLK × 4
• The WDT clock (WDCLK) source is a 2 MHz clock derived from the SFRO, or the
external clock as set by the SYSCLKCTRL register
8.13.2 General description
The WDT consists of a divide by 4 fixed prescaler and a 24-bit counter. The clock is fed
to the timer via a prescaler. The timer decrements when clocked. The minimum value by
which the counter is decremented is 0xFF. Setting a value lower than 0xFF causes 0xFF
to be loaded in the counter. Hence the minimum WDT interval is (TWDCLK × 256 × 4)
and the maximum is (TWDCLK × 2
24
× 4), in multiples of (TWDCLK × 4).
8.14 System tick timer
8.14.1 Features
• Simple 24-bit timer
• Uses dedicated exception vector
• Clocked internally by the system clock or the system clock divided by two
8.14.2 General description
The SYSTICK timer is a part of the Cortex-M0+. The SYSTICK timer can be used to
generate a fixed periodic interrupt for use by an operating system or other system.
Since the SYSTICK timer is a part of the Cortex-M0+, it facilitates porting of software by
providing a standard timer available on Cortex-M0+ based devices. The SYSTICK timer
can be used for management software.
Refer to the Cortex-M0+ Devices - Generic User Guide (Ref. 2) for details.