P83CL882 datasheet(39/88 Pages) PHILIPS

39 / 88 page

2001 Jun 19

Philips Semiconductors

Product speciﬁcation

80C51 Ultra Low Power (ULP) telephony controller

P83CL882

6.6.2

TIMER 2 MODES IN GENERAL

Timer 2 can operate in three different modes:

• Capture mode

• Auto-reload mode

• Clock output mode.

In these three modes the timer/counter operates on events

detected on inputs T2 and T2EX.

Table 52 shows the list of T2CON and T2MOD register bits

which set the Timer 2 mode of operation.

Sections 6.6.3 to 6.6.5 describe the Timer 2 modes.

Table 52 Timer 2 modes

6.6.3

CAPTURE MODE

In the Capture mode, registers T2RCH/T2RCL are used to

capture the T2H/T2L register data.

There are two options selected by the T2CON.EXEN2 bit.

This bit enables or disables the events of the external

trigger input T2EX.

• T2CON.C/T2 = 1: Timer 2 is a 16-bit counter. The

counter increments at each LOW-to-HIGH transition on

input T2 at a maximum rate of one each 12 fpsc cycles.

• T2CON.C/T2 = 0: Timer 2 is a 16-bit timer. The timer

increments each 6 fPSC cycles.

• T2CON.EXEN2 = 1: The external trigger input T2EX is

enabled. Timer 2 is a 16-bit timer or counter.

– If T2MOD.DCEN = 0, a HIGH-to-LOW transition at

input T2EX causes the current Timer 2 value

(T2H/T2L data) to be captured into T2RCH/T2RCL,

and bit T2CON.EXF2 becomes set.

– If T2MOD.DCEN = 1, bit T2CON.EXEN2 has no

influence. Overflowing of Timer 2 sets bit

T2CON.TF2.

• T2CON.EXEN2 = 0: The external trigger input T2EX is

disabled. Timer 2 is a 16-bit timer or counter. The T2EX

input is ignored. Overflowing of Timer 2 sets bit

T2CON.TF2.

The Capture mode is shown in Fig.19.

CP/RL2 C/T2OE

C/T2

OPERATING MODE

16-bit auto-reload

16-bit capture

clock output

handbook, full pagewidth

MBH998

TL2

(8 BITS)

COMPARATOR 1

(16 BITS)

TR2

control

TH2

(8 BITS)

COMP2L

COMP2H

ECOMP

RCAP2L

RCAP2H

EXF2

TF2

COMP

Timer 2

interrupt

port

P1.2

EXEN2

control

C/T2 = 1

T2 pin

OSC

transition

detector

T2EX pin

C/T2 = 0

capture

Fig.19 Timer 2 in Capture mode.

P83CL882 датащи(PDF) 39 Page - NXP Semiconductors

P83CL882 датащи(HTML) 39 Page - NXP Semiconductors

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

датащи скачать

ссылки URL