AT43USB325E-AU Atmel, AT43USB325E-AU Datasheet - Page 44

• 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

6.2.1
6.2.2
44
AT43USB325
Timer/Counter0 Control Register – TCCR0
Timer/Counter0 – TCNT0
• Bits 7..3 – Res: Reserved Bits
These bits are reserved bits in the AT43USB325 and always read as zero.
• Bits 2, 1, 0 – CS02, CS01, CS00: Clock Select0, bit 2, 1 and 0
The Clock Select0 bits 2, 1 and 0 define the prescaling source of Timer/Counter0.
Table 6-1.
The Stop condition provides a Timer Enable/Disable function. The CK down divided modes are
scaled directly from the CK oscillator clock. If the external pin modes are used for
Timer/Counter0, transitions on PB0/(T0) will clock the counter even if the pin is configured as an
output. This feature can give the user SW control of the counting.
The Timer/Counter0 is realized as an up-counter with read and write access. If the
Timer/Counter0 is written and a clock source is present, the Timer/Counter0 continues counting
in the clock cycle following the write operation.
Read/Write
Initial Value
$33 ($53)
Read/Write
Initial Value
$32 ($52)
Bit
Bit
CS02
0
0
0
0
1
1
1
1
R
Clock 0 Prescale Select
7
–
0
MSB
R/W
7
0
CS01
R
6
–
0
R/W
0
0
1
1
0
0
1
1
0
6
–
R
5
–
0
R/W
5
–
0
CS00
0
1
0
1
0
1
0
1
R
4
–
0
R/W
4
–
0
R
3
–
0
Description
Stop, the Timer/Counter0 is stopped
CK
CK/8
CK/64
CK/256
CK/1024
External Pin T0, falling edge
External Pin T0, rising edge
R/W
3
–
0
CS02
R/W
2
0
R/W
2
–
0
CS01
R/W
1
0
R/W
1
–
0
CS00
R/W
LSB
R/W
0
0
0
0
3355C–USB–4/05
TCCR0
TCNT0