AT43USB325E-AC Atmel, AT43USB325E-AC Datasheet - Page 46

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

Specifications of AT43USB325E-AC

• 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: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

6.4
Figure 6-4.
46
16-bit Timer/Counter1 Operation
ACIC: COMPARATOR IC ENABLE
ACC0: COMPARATOR OUTPUT
AT43USB325
ICP
ICP Pin Schematic Diagram
The 16-bit Timer/Counter1 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/Counter1 Control Reg-
isters (TCCR1A and TCCR1B). The different status flags (overflow, compare match and capture
event) are found in the Timer/Counter Interrupt Flag Register (TIFR). Control signals are found
in the Timer/Counter1 Control Registers (TCCR1A and TCCR1B). The interrupt enable/disable
settings for Timer/Counter1 are found in the Timer/Counter Interrupt Mask Register (TIMSK).
When Timer/Counter1 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 16-bit Timer/Counter1 features both a high resolution and a high accuracy usage with the
lower prescaling opportunities. Similarly, the high prescaling opportunities makes the
Timer/Counter1 useful for lower speed functions or exact timing functions with infrequent
actions.
The Timer/Counter1 supports two Output Compare functions using the Output Compare Regis-
ter 1 A and B (OCR1A and OCR1B) as the data sources to be compared to the Timer/Counter1
contents. The Output Compare functions include optional clearing of the counter on compareA
match, and actions on the Output Compare pins on both compare matches.
Timer/Counter1 can also be used as a 8-, 9- or 10-bit Pulse With Modulator. In this mode the
counter and the OCR1A/OCR1B registers serve as a dual glitch-free stand-alone PWM with
centered pulses.
The Input Capture function of Timer/Counter1 provides a capture of the Timer/Counter1 con-
tents to the Input Capture Register - ICR1, triggered by an external event on the Input Capture
Pin (ICP/PF3). The actual capture event settings are defined by the Timer/Counter1 Control
Register (TCCR1B). The AT43USB325 has no analog comparator and the mux control signal,
ACO, is permanently set so that the ICP input is routed to the noise canceler.
If the noise canceler function is enabled, the actual trigger condition for the capture event is
monitored over 4 samples, and all 4 must be equal to activate the capture flag.
1
0
NOISE CANCELER
ICNC1
EDGE SELECT
ICES1
ACIC
ACO
ICF1
3355C–USB–4/05