Datasheet

168
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
ICR1H and ICR1L – Input
Capture Register 1
ICR3H and ICR3L – Input
Capture Register 3 –
ICR4H and ICR4L – Input
Capture Register 4
ICR5H and ICR5L – Input
Capture Register 5
The Input Capture is updated with the counter (TCNTn) value each time an event occurs
on the ICPn pin (or optionally on the Analog Comparator output for Timer/Counter1).
The Input Capture can be used for defining the counter TOP value.
The Input Capture Register is 16-bit in size. To ensure that both the high and low bytes
are read simultaneously when the CPU accesses these registers, the access is per-
formed using an 8-bit temporary High Byte Register (TEMP). This temporary register is
shared by all the other 16-bit registers. See “Accessing 16-bit Registers” on page 139.
Bit 76543210
(0x87) ICR1[15:8] ICR1H
(0x86) ICR1[7:0] ICR1L
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
(0x97) ICR3[15:8] ICR3H
(0x96) ICR3[7:0] ICR3L
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
(0xA7) ICR4[15:8] ICR4H
(0xA6) ICR4[7:0] ICR4L
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
(0x127) ICR5[15:8] ICR5H
(0x126) ICR5[7:0] ICR5L
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000