AT90CAN128-16AI Atmel, AT90CAN128-16AI Datasheet - Page 58

• Manufacturer Part Number: AT90CAN128-16AI
• Description: IC MCU AVR FLASH 128K 64TQFP
• Manufacturer: Atmel
• Series: AVR® 90CANr

Specifications of AT90CAN128-16AI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: CAN, EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• For Use With: ATDVK90CAN1 - KIT DEV FOR AT90CAN128 MCU
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

7.3.1
58
AT90CAN32/64/128
Watchdog Timer Control Register – WDTCR
• Bits 7..5 – Reserved Bits
These bits are reserved bits for future use.
• Bit 4 – WDCE: Watchdog Change Enable
This bit must be set when the WDE bit is written to logic zero. Otherwise, the Watchdog will not
be disabled. Once written to one, hardware will clear this bit after four clock cycles. Refer to the
description of the WDE bit for a Watchdog disable procedure. This bit must also be set when
changing the prescaler bits.
Watchdog Timer” on page 59.
• Bit 3 – WDE: Watchdog Enable
When the WDE is written to logic one, the Watchdog Timer is enabled, and if the WDE is written
to logic zero, the Watchdog Timer function is disabled. WDE can only be cleared if the WDCE bit
has logic level one. To disable an enabled Watchdog Timer, the following procedure must be
followed:
In safety level 2, it is not possible to disable the Watchdog Timer, even with the algorithm
described above.
Timer” on page 59.
• Bits 2..0 – WDP2, WDP1, WDP0: Watchdog Timer Prescaler 2, 1, and 0
The WDP2, WDP1, and WDP0 bits determine the Watchdog Timer prescaling when the Watch-
dog Timer is enabled. The different prescaling values and their corresponding Timeout Periods
are shown in
Table 7-6.
1. In the same operation, write a logic one to WDCE and WDE. A logic one must be writ-
2. Within the next four clock cycles, write a logic 0 to WDE. This disables the Watchdog.
WDP2
Initial Value
Read/Write
0
0
0
0
1
1
1
1
Bit
ten to WDE even though it is set to one before the disable operation starts.
WDP1
Table
0
0
1
1
0
0
1
1
Watchdog Timer Prescale Select
R
7
–
0
See “Timed Sequences for Changing the Configuration of the Watchdog
7-6.
WDP0
0
1
0
1
0
1
0
1
R
6
–
0
See “Timed Sequences for Changing the Configuration of the
Oscillator Cycles
R
5
–
0
Number of WDT
32/64K cycles
1,024K cycles
2,048K cycles
256K cycles
512K cycles
16K cycles
32K cycles
64K cycles
WDCE
R/W
0
4
WDE
R/W
3
0
Typical Time-out at
WDP2
R/W
2
0
V
CC
17.1 ms
34.3 ms
68.5 ms
0.14 s
0.27 s
0.55 s
1.1 s
2.2 s
= 3.0V
WDP1
R/W
1
0
WDP0
R/W
0
0
Typical Time-out at
WDTCR
V
CC
16.3 ms
32.5 ms
7679H–CAN–08/08
65 ms
0.13 s
0.26 s
0.52 s
1.0 s
2.1 s
= 5.0V