AT89LP6440 datasheet(61/194 Pages) ATMEL

61 / 194 page

3706A–MICRO–9/09

AT89LP6440 - Preliminary

12.2

Capture Mode

In the Capture mode, Timer 2 is a fixed 16-bit timer or counter that counts up from MIN to MAX.

An overflow from MAX to MIN sets bit TF2 in T2CON. If EXEN2 = 1, a 1-to-0 transition at exter-

nal input T2EX also causes the current value in TH2 and TL2 to be captured into RCAP2H and

RCAP2L, respectively. In addition, the transition at T2EX causes bit EXF2 in T2CON to be set.

The EXF2 and TF2 bits can generate an interrupt. Capture mode is illustrated in Figure 12-1.

The Timer 2 overflow rate in Capture mode is given by the following equation:

PHS [2-0]

CCA Phase Mode. PWM channels may be grouped by 2, 3 or 4 such that only one channel in a group produces a pulse

in any one period. The PHS[2-0] bits may only be written when the timer is not active, i.e. TR2 = 0.

PHS2

PHS1

PHS0

Phase Mode

000Disabled, all channels active

0012-phase output on channels A & B

0103-phase output on channels A, B & C

0114-phase output on channels A, B, C & D

100Dual 2-phase output on channels A & B and C & D

101reserved

110reserved

111reserved

T2CM

[1-0]

Timer 2 Count Mode.

T2CM1

T2CM0

Count Mode

Standard Timer 2 (up count:

)

Clear on RCAP compare (up count:

)

10Dual-slope with single update (up-down count:

)

11Dual-slope with double update (up-down count:

)

T2OE

Timer 2 Output Enable. When T2OE = 1 and C/T2 = 0, the T2 pin will toggle after every Timer 2 overflow.

DCEN

Timer 2 Down Count Enable. When Timer 2 operates in Auto-Reload mode and EXEN2 = 1, setting DCEN = 1 will cause

Timer 2 to count up or down depending on the state of T2EX.

Symbol

Function

BOTTOM

MAX

→

MIN

TOP

→

MIN

TOP

MIN

→→

MIN

TOP

MIN

→→

Capture Mode:

Time-out Period

65536

Oscillator Frequency

-------------------------------------------------------

TPS

()

AT89LP6440 Datasheet(PDF) 61 Page - ATMEL Corporation

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