ATTINY2313A-SUR Atmel, ATTINY2313A-SUR Datasheet - Page 92

• Manufacturer Part Number: ATTINY2313A-SUR
• Description: MCU AVR 2KB FLASH 20MHZ 20SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY2313A-SUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 18
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Converters: -

12.5.1
92
ATtiny2313A/4313
Input Capture Trigger Source
Figure 12-3. Input Capture Unit Block Diagram
When a change of the logic level (an event) occurs on the Input Capture pin (ICP1), alternatively
on the Analog Comparator output (ACO), and this change confirms to the setting of the edge
detector, a capture will be triggered. When a capture is triggered, the 16-bit value of the counter
(TCNT1) is written to the Input Capture Register (ICR1). The Input Capture Flag (ICF1) is set at
the same system clock as the TCNT1 value is copied into ICR1 Register. If enabled (ICIE1 = 1),
the Input Capture Flag generates an Input Capture interrupt. The ICF1 flag is automatically
cleared when the interrupt is executed. Alternatively the ICF1 flag can be cleared by software by
writing a logical one to its I/O bit location.
Reading the 16-bit value in the Input Capture Register (ICR1) is done by first reading the low
byte (ICR1L) and then the high byte (ICR1H). When the low byte is read the high byte is copied
into the high byte temporary register (TEMP). When the CPU reads the ICR1H I/O location it will
access the TEMP Register.
The ICR1 Register can only be written when using a Waveform Generation mode that utilizes
the ICR1 Register for defining the counter’s TOP value. In these cases the Waveform Genera-
tion mode (WGM13:0) bits must be set before the TOP value can be written to the ICR1
Register. When writing the ICR1 Register the high byte must be written to the ICR1H I/O location
before the low byte is written to ICR1L.
For more information on how to access the 16-bit registers refer to
on page
The main trigger source for the Input Capture unit is the Input Capture pin (ICP1).
Timer/Counter1 can alternatively use the Analog Comparator output as trigger source for the
Input Capture unit. The Analog Comparator is selected as trigger source by setting the Analog
Comparator Input Capture (ACIC) bit in the Analog Comparator Control and Status Register
(ACSR). Be aware that changing trigger source can trigger a capture. The Input Capture Flag
must therefore be cleared after the change.
106.
ICPn
WRITE
ICRnH (8-bit)
TEMP (8-bit)
Comparator
Analog
ICRn (16-bit Register)
ACO*
ICRnL (8-bit)
ACIC*
DATA BUS
Canceler
Noise
ICNC
(8-bit)
TCNTnH (8-bit)
TCNTn (16-bit Counter)
Detector
ICES
Edge
“Accessing 16-bit Registers”
TCNTnL (8-bit)
ICFn (Int.Req.)
8246A–AVR–11/09