ATMEGA1284PR231-AU Atmel, ATMEGA1284PR231-AU Datasheet - Page 53

BUNDLE ATMEGA1284P/RF231 TQFP

ATMEGA1284PR231-AU

Manufacturer Part Number
ATMEGA1284PR231-AU
Description
BUNDLE ATMEGA1284P/RF231 TQFP
Manufacturer
Atmel
Datasheet

Specifications of ATMEGA1284PR231-AU

Frequency
2.4GHz
Modulation Or Protocol
802.15.4 Zigbee, 6LoWPAN, RF4CE, SP100, WirelessHART™, ISM
Data Interface
PCB, Surface Mount
Memory Size
128kB Flash, 4kB EEPROM, 16kB RAM
Antenna Connector
PCB, Surface Mount
Package / Case
44-TQFP, 44-VQFP
Processor Series
ATMEGA128x
Core
AVR8
Data Bus Width
8 bit
Program Memory Type
Flash
Program Memory Size
128 KB
Data Ram Size
16 KB
Development Tools By Supplier
ATAVRRZ541, ATAVRRAVEN, ATAVRRZUSBSTICK, ATAVRISP2, ATAVRRZ201
For Use With
ATSTK600 - DEV KIT FOR AVR/AVR32
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Supply
-
Power - Output
-
Operating Temperature
-
Applications
-
Sensitivity
-
Data Rate - Maximum
-
Current - Transmitting
-
Current - Receiving
-
Lead Free Status / Rohs Status
 Details
9.3
9.3.1
9.3.2
8059D–AVR–11/09
Watchdog Timer
Features
Overview
ATmega1284P has an Enhanced Watchdog Timer (WDT). The WDT is a timer counting cycles
of a separate on-chip 128 kHz oscillator. The WDT gives an interrupt or a system reset when the
counter reaches a given time-out value. In normal operation mode, it is required that the system
uses the WDR - Watchdog Timer Reset - instruction to restart the counter before the time-out
value is reached. If the system doesn't restart the counter, an interrupt or system reset will be
issued.
Figure 9-7.
In Interrupt mode, the WDT gives an interrupt when the timer expires. This interrupt can be used
to wake the device from sleep-modes, and also as a general system timer. One example is to
limit the maximum time allowed for certain operations, giving an interrupt when the operation
has run longer than expected. In System Reset mode, the WDT gives a reset when the timer
expires. This is typically used to prevent system hang-up in case of runaway code. The third
mode, Interrupt and System Reset mode, combines the other two modes by first giving an inter-
rupt and then switch to System Reset mode. This mode will for instance allow a safe shutdown
by saving critical parameters before a system reset.
The Watchdog always on (WDTON) fuse, if programmed, will force the Watchdog Timer to Sys-
tem Reset mode. With the fuse programmed the System Reset mode bit (WDE) and Interrupt
mode bit (WDIE) are locked to 1 and 0 respectively. To further ensure program security, altera-
tions to the Watchdog set-up must follow timed sequences. The sequence for clearing WDE and
changing time-out configuration is as follows:
Clocked from separate On-chip Oscillator
3 Operating modes
Selectable Time-out period from 16ms to 8s
Possible Hardware fuse Watchdog always on (WDTON) for fail-safe mode
– Interrupt
– System Reset
– Interrupt and System Reset
WATCHDOG
RESET
Watchdog Timer
OSCILLATOR
128kHz
WDIE
WDIF
WDE
ATmega1284P
WDP0
WDP1
WDP2
WDP3
MCU RESET
INTERRUPT
53

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