AT43USB325E-AU Atmel, AT43USB325E-AU Datasheet - Page 43

• 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
Figure 6-2.
3355C–USB–4/05
8-bit Timer/Counter0
Timer/Counter0 Block Diagram
7
Timer Int. Mask Register
Timer/Counter0
The 8-bit Timer/Counter0 can select clock source from CK, prescaled CK or an external pin. In
addition it can be stopped as described in the specification for the Timer/Counter0 Control Reg-
ister (TCCR0). The overflow status flag is found in the Timer/Counter Interrupt Flag Register
(TIFR). Control signals are found in the Timer/Counter0 Control Register (TCCR0). The interrupt
enable/disable settings for Timer/Counter0 are found in the Timer/Counter Interrupt Mask Regis-
ter - TIMSK.
When Timer/Counter0 is externally clocked, the external signal is synchronized with the oscilla-
tor frequency of the CPU. To assure proper sampling of the external clock, the minimum time
between two external clock transitions must be at least one internal CPU clock period. The
external clock signal is sampled on the rising edge of the internal CPU clock.
The 8-bit Timer/Counter0 features both a high resolution and a high accuracy usage with the
lower prescaling opportunities. Similarly, the high prescaling opportunities make the
Timer/Counter0 useful for lower speed functions or exact timing functions with infrequent
actions.
(TCNT0)
(TIMSK)
0
Overflow IRQ
T/C0
T/C Clock Source
Timer Int. Flag Register
(TIFR)
Control
Logic
T/C0 Control Register
(TCCR0)
AT43USB325
CK
T0
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