AT90CAN64 Atmel Corporation, AT90CAN64 Datasheet - Page 58
AT90CAN64
Manufacturer Part Number
AT90CAN64
Description
Manufacturer
Atmel Corporation
Specifications of AT90CAN64
Flash (kbytes)
64 Kbytes
Pin Count
64
Max. Operating Frequency
16 MHz
Cpu
8-bit AVR
# Of Touch Channels
16
Hardware Qtouch Acquisition
No
Max I/o Pins
53
Ext Interrupts
8
Usb Speed
No
Usb Interface
No
Spi
1
Twi (i2c)
1
Uart
2
Can
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
No
Crypto Engine
No
Sram (kbytes)
4
Eeprom (bytes)
2048
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
No
Temp. Range (deg C)
-40 to 85
I/o Supply Class
2.7 to 5.5
Operating Voltage (vcc)
2.7 to 5.5
Fpu
No
Mpu / Mmu
no / no
Timers
4
Output Compare Channels
8
Input Capture Channels
2
Pwm Channels
7
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
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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