Datasheet
Table Of Contents
- Features
- 1. Ordering Information
- 2. Typical Applications
- 3. Pinout and Block Diagram
- 4. Overview
- 5. Resources
- 6. Capacitive Touch Sensing
- 7. CPU
- 8. Memories
- 9. EDMA – Enhanced DMA Controller
- 10. Event System
- 11. System Clock and Clock options
- 11.1 Features
- 11.2 Overview
- 11.3 Clock Sources
- 11.3.1 32kHz Ultra Low Power Internal Oscillator
- 11.3.2 32.768kHz Calibrated Internal Oscillator
- 11.3.3 32.768kHz Crystal Oscillator
- 11.3.4 0.4 - 16MHz Crystal Oscillator
- 11.3.5 8MHz Calibrated Internal Oscillator
- 11.3.6 32MHz Run-time Calibrated Internal Oscillator
- 11.3.7 External Clock Sources
- 11.3.8 PLL with 1x-31x Multiplication Factor
- 12. Power Management and Sleep Modes
- 13. System Control and Reset
- 14. WDT – Watchdog Timer
- 15. Interrupts and Programmable Multilevel Interrupt Controller
- 16. I/O Ports
- 17. Timer Counter Type 4 and 5
- 18. WeX – Waveform Extension
- 19. Hi-Res – High Resolution Extension
- 20. Fault Extension
- 21. RTC – 16-bit Real-Time Counter
- 22. TWI – Two-Wire Interface
- 23. SPI – Serial Peripheral Interface
- 24. USART
- 25. IRCOM – IR Communication Module
- 26. XCL – XMEGA Custom Logic Module
- 27. CRC – Cyclic Redundancy Check Generator
- 28. ADC – 12-bit Analog to Digital Converter
- 29. DAC – Digital to Analog Converter
- 30. AC – Analog Comparator
- 31. Programming and Debugging
- 32. Pinout and Pin Functions
- 33. Peripheral Module Address Map
- 34. Instruction Set Summary
- 35. Packaging Information
- 36. Electrical Characteristics
- 36.1 Absolute Maximum Ratings
- 36.2 General Operating Ratings
- 36.3 Current Consumption
- 36.4 Wake-up Time from Sleep Modes
- 36.5 I/O Pin Characteristics
- 36.6 ADC Characteristics
- 36.7 DAC Characteristics
- 36.8 Analog Comparator Characteristics
- 36.9 Bandgap and Internal 1.0V Reference Characteristics
- 36.10 External Reset Characteristics
- 36.11 Power-on Reset Characteristics
- 36.12 Flash and EEPROM Characteristics
- 36.13 Clock and Oscillator Characteristics
- 36.13.1 Calibrated 32.768kHz Internal Oscillator Characteristics
- 36.13.2 Calibrated 8MHz Internal Oscillator Characteristics
- 36.13.3 Calibrated and Tunable 32MHz Internal Oscillator Characteristics
- 36.13.4 32 kHz Internal ULP Oscillator Characteristics
- 36.13.5 Internal Phase Locked Loop (PLL) Characteristics
- 36.13.6 External Clock Characteristics
- 36.13.7 External 16MHz Crystal Oscillator and XOSC Characteristics
- 36.13.8 External 32.768kHz Crystal Oscillator and TOSC Characteristics
- 36.14 SPI Characteristics
- 36.15 Two-Wire Interface Characteristics
- 37. Typical Characteristics
- 37.1 Current Consumption
- 37.2 I/O Pin Characteristics
- 37.3 ADC Characteristics
- 37.4 DAC Characteristics
- 37.5 AC Characteristics
- 37.6 Internal 1.0V Reference Characteristics
- 37.7 BOD Characteristics
- 37.8 External Reset Characteristics
- 37.9 Power-on Reset Characteristics
- 37.10 Oscillator Characteristics
- 37.11 Two-wire Interface Characteristics
- 37.12 PDI Characteristics
- 38. Errata – ATxmega32E5 / ATxmega16E5 / ATxmega8E5
- 39. Revision History
- Table of Contents
27
XMEGA E5 [DATASHEET]
Atmel-8153J–AVR-ATxmega8E5-ATxmega16E5-ATxmega32E5_Datasheet–11/2014
14. WDT – Watchdog Timer
14.1 Features
Issues a device reset if the timer is not reset before its timeout period
Asynchronous operation from dedicated oscillator
1kHz output of the 32kHz ultra low power oscillator
11 selectable timeout periods, from 8ms to 8s
Two operation modes:
Normal mode
Window mode
Configuration lock to prevent unwanted changes
14.2 Overview
The watchdog timer (WDT) is a system function for monitoring correct program operation. It makes it possible to recover
from error situations such as runaway or deadlocked code. The WDT is a timer, configured to a predefined timeout
period, and is constantly running when enabled. If the WDT is not reset within the timeout period, it will issue a
microcontroller reset. The WDT is reset by executing the WDR (watchdog timer reset) instruction from the application
code.
The window mode makes it possible to define a time slot or window inside the total timeout period during which WDT
must be reset. If the WDT is reset outside this window, either too early or too late, a system reset will be issued.
Compared to the normal mode, this can also catch situations where a code error causes constant WDR execution.
The WDT will run in active mode and all sleep modes, if enabled. It is asynchronous, runs from a CPU-independent clock
source, and will continue to operate to issue a system reset even if the main clocks fail.
The configuration change protection mechanism ensures that the WDT settings cannot be changed by accident. For
increased safety, a fuse for locking the WDT settings is also available.