ATMEGA64M1-15MZ Atmel, ATMEGA64M1-15MZ Datasheet - Page 52

• Manufacturer Part Number: ATMEGA64M1-15MZ
• Description: MCU AVR 64KB FLASH 3PSC 32-VQFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA64M1-15MZ

• Package / Case: 32-VQFN
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Eeprom Size: 2K x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Program Memory Size: 64KB (64K x 8)
• Data Converters: A/D 11x10b; D/A 1x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Connectivity: CAN, LIN, SPI, UART/USART
• Core Size: 8-Bit
• Processor Series: ATMEGA64x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, ATADAPCAN01
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Lead Free Status / Rohs Status: Details

7.4
52
Watchdog Timer
Atmel ATmega16/32/64/M1/C1
ATmega16/32/64/M1/C1 has an Enhanced Watchdog Timer (WDT). The main features are:
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Figure 7-7.
The Watchdog Timer (WDT) is a timer counting cycles of a separate on-chip 128 kHz oscilla-
tor. 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 sys-
tem doesn't restart the counter, an interrupt or system reset will be issued.
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 opera-
tion 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 interrupt 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 Timer Always On” (WDTON) fuse, if programmed, will force the Watchdog
Timer to System 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, alterations to the Watchdog set-up must follow timed sequences. The sequence for
clearing WDE and changing time-out configuration is as follows:
1. In the same operation, write a logic one to the Watchdog change enable bit (WDCE)
2. Within the next four clock cycles, write the WDE and Watchdog prescaler bits (WDP)
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
and WDE. A logic one must be written to WDE regardless of the previous value of the
WDE bit.
as desired, but with the WDCE bit cleared. This must be done in one operation.
Watchdog Timer
OSCILLATOR
128 KHz
WDP3
WDIF
WDIE
INTERRUPT
MCU RESET
7647G–AVR–09/11