at43usb320a ATMEL Corporation, at43usb320a Datasheet - Page 42

• Manufacturer Part Number: at43usb320a
• Description: Full-speed Usb Microcontroller With An Embedded Hub
• Manufacturer: ATMEL Corporation

16-bit
Timer/Counter1
Operation
Figure 12. ICP Pin Schematic Diagram
42
ACIC: COMPARATOR IC ENABLE
ACC0: COMPARATOR OUTPUT
AT43USB320A
ICP
1
0
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
Registers (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 oscil-
lator 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 Reg-
iste r 1 A and B (OCR1A and OCR1 B) as th e d ata sources to b e compa re d 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). In addition, the Analog Comparator can be set to trigger the Input Cap-
ture. Refer to .
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.
NOISE CANCELER
ICNC1
EDGE SELECT
ICES1
ACIC
ACO
ICF1
1443E–USB–4/04