ATmega16HVB datasheet(86/273 Pages) ATMEL

86 / 273 page

8042A–AVR–07/09

ATmega16HVB/32HVB

value of TCNTn, the counter will miss the Compare Match. The counter will then have to count to

its maximum value (0xFFFF) and wrap around starting at 0x0000 before Compare Match can

occur. As for the 16-bit Mode, the TOVn Flag is set in the same timer clock cycle that the counter

counts from MAX to 0x0000.

17.5.5

8-bit Input Capture Mode

The Timer/Counter can be used in a 8-bit Input Capture mode, see Table 17-2 on page 84 for bit

settings. For full description, see ”Input Capture Unit” on page 86.

17.5.6

16-bit Input Capture Mode

The Timer/Counter can also be used in a 16-bit Input Capture mode, see Table 17-2 on page 84

for bit settings. For full description, see ”Input Capture Unit” on page 86.

17.6

Input Capture Unit

The Timer/Counter incorporates an Input Capture unit that can capture external events and give

them a time-stamp indicating time of occurrence. The external signal indicates an event, or mul-

tiple events. For Timer/Counter0, the events can be applied via the PB0 pin (ICP00), or

alternatively via the osi_posedge pin on the Oscillator Sampling Interface (ICP01). For

Timer/Counter1, the events can be applied by the Battery Protection Interrupt (ICP10) or alter-

natively by the Voltage Regulator Interrupt (ICP11). The time-stamps can then be used to

calculate frequency, duty-cycle, and other features of the signal applied. Alternatively the time-

stamps can be used for creating a log of the events.

The Input Capture unit is illustrated by the block diagram shown in Figure 17-4 on page 86. The

elements of the block diagram that are not directly a part of the Input Capture unit are gray

shaded.

Figure 17-4. Input Capture Unit Block Diagram

The Output Compare Register OCRnA is a dual-purpose register that is also used as an 8-bit

Input Capture Register ICRn. In 16-bit Input Capture mode the Output Compare Register

OCRnB serves as the high byte of the Input Capture Register ICRn. In 8-bit Input Capture mode

the Output Compare Register OCRnB is free to be used as a normal Output Compare Register,

ICFn (Int.Req.)

WRITE

ICRn (16-bit Register)

OCRnB (8-bit)

Noise

Canceler

ICPn0

Edge

Detector

TEMP (8-bit)

DATA BUS (8-bit)

OCRnA (8-bit)

TCNTn (16-bit Counter)

TCNTnH (8-bit)

TCNTnL (8-bit)

ICNCn

ICESn

ICPn1

ICSn

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