AT43USB325E-AU Atmel, AT43USB325E-AU Datasheet - Page 53

• Manufacturer Part Number: AT43USB325E-AU
• Description: IC USB KEYBOARD CTRLR 64LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB325E-AU

• Applications: Keyboard Controller
• Core Processor: AVR
• Program Memory Type: SRAM (16 kB)
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: SPI, 3-Wire Serial
• Number Of I /o: 42
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.5
3355C–USB–4/05
Watchdog Timer
down-counting compare match is not interpreted to be reached before the next time the counter
reaches the TOP value, making a one-period PWM pulse.
Table 6-7.
Note:
In PWM mode, the Timer Overflow Flag1, TOV1, is set when the counter advances from $0000.
Timer Overflow Interrupt1 operates exactly as in normal Timer/Counter mode, i.e. it is executed
when TOV1 is set provided that Timer Overflow Interrupt1 and global interrupts are enabled.
This also applies to the Timer Output Compare1 flags and interrupts.
The Watchdog Timer is clocked from a 1 MHz clock derived from the 6 MHz on chip oscillator.
By controlling the Watchdog Timer prescaler, the Watchdog reset interval can be adjusted, see
Table 6-8
dog Timer. Eight different clock cycle periods can be selected to determine the reset period. If
the reset period expires without another Watchdog reset, the AT43USB325 resets and executes
from the reset vector.
To prevent unintentional disabling of the watchdog, a special turn-off sequence must be followed
when the watchdog is disabled. Refer to the description of the Watchdog Timer Control Register
for details.
Figure 6-6.
COM1X1
1
1
1
1
X = A or B
for a detailed description. The WDR (Watchdog Reset) instruction resets the Watch-
PWM Outputs OCR1X = $0000 or Top
Watchdog Timer
Watchdog
1 MHz Clock
Reset
COM1X0
0
0
1
1
WDP0
WDP1
WDP2
OCR1X
WDE
$0000
$0000
TOP
TOP
Watchdog Prescaler
MCU Reset
Output OC1X
AT43USB325
H
H
L
L
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