ATmega324P datasheet(157/377 Pages) ATMEL

157 / 377 page

157

7674F–AVR–09/09

ATmega164P/324P/644P

• Bit 6 – FOC2B: Force Output Compare B

The FOC2B bit is only active when the WGM bits specify a non-PWM mode.

However, for ensuring compatibility with future devices, this bit must be set to zero when

TCCR2B is written when operating in PWM mode. When writing a logical one to the FOC2B bit,

an immediate Compare Match is forced on the Waveform Generation unit. The OC2B output is

changed according to its COM2B1:0 bits setting. Note that the FOC2B bit is implemented as a

strobe. Therefore it is the value present in the COM2B1:0 bits that determines the effect of the

forced compare.

A FOC2B strobe will not generate any interrupt, nor will it clear the timer in CTC mode using

OCR2B as TOP.

The FOC2B bit is always read as zero.

• Bits 5:4 – Res: Reserved Bits

These bits are reserved bits in the ATmega164P/324P/644P and will always read as zero.

• Bit 3 – WGM22: Waveform Generation Mode

See the description in the “TCCR2A – Timer/Counter Control Register A” on page 153.

• Bit 2:0 – CS22:0: Clock Select

The three Clock Select bits select the clock source to be used by the Timer/Counter, see Table

15-9 on page 157.

If external pin modes are used for the Timer/Counter0, transitions on the T0 pin will clock the

counter even if the pin is configured as an output. This feature allows software control of the

counting.

15.11.3

TCNT2 – Timer/Counter Register

The Timer/Counter Register gives direct access, both for read and write operations, to the

Timer/Counter unit 8-bit counter. Writing to the TCNT2 Register blocks (removes) the Compare

Table 15-9.

Clock Select Bit Description

CS22

CS21

CS20

Description

No clock source (Timer/Counter stopped).

001

clkT2S/(No prescaling)

010

clkT2S/8 (From prescaler)

011

clkT2S/32 (From prescaler)

100

clkT2S/64 (From prescaler)

101

clkT2S/128 (From prescaler)

110

clkT2S/256 (From prescaler)

111

clkT2S/1024 (From prescaler)

Bit

76543210

(0xB2)

TCNT2[7:0]

TCNT2

Read/Write

R/W

Initial Value

00000000

ATmega324P Datasheet(PDF) 157 Page - ATMEL Corporation

ATmega324P Datasheet(HTML) 157 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL