EM73A89B datasheet(21/58 Pages) EMC

21 / 58 page

* This specification are subject to be changed without notice.

EM73A89B

4-BIT MICRO-CONTROLLER FOR LCD PRODUCT

8.16.2001

Preliminary

Internal pulse

TimerB(TimerA) value

n+1

n+2

n+3

n+4

n+5

P8.1/TRGB(P8.3/TRGA)

PROGRAM EXAMPLE: To generate TRGA interrupt request after 60 ms with system clock LXlN=32KHz

LDIA

#0100B

;

EXAE

; enable mask 2

EICIL

110111b

; interrupt latch ←0, enable EI

LDIA

#0Ah;

STATAL;

LDIA

#00h;

STATAM;

LDIA

#0Fh;

STATAH;

LDIA

#1000B;

OUTA

P28

; enable timerA with internal pulse rate: LXIN/23 Hz

NOTE: The preset value of timer/counter register is calculated as following procedure.

Internal pulse rate: LXIN/23 ; LXIN = 32KHz

The time of timer counter count one = 23 /LXIN = 8/32768=0.244ms

The number of internal pulse to get timer overflow = 60 ms/0.244ms = 245.901= 0F6h

The preset value of timer/counter register = 1000h - 0F6h = F0Ah

PULSE WIDTH MEASUREMENT MODE

Under the pulse width measurement mode, the counter is incresed at the rising edge of internal pulse during

external timer/counter input (P8.1/TRGB, P8.3/TRGA) in high level, interrupt request is generated as soon as

timer/counter count overflow.

PROGRAM EXAMPLE: Enable timerA by pulse width measurement mode.

LDIA

#1100b ;

OUTA

P28

; Enable timerA with pulse width measurement mode.

TIMER MODE

Under timer mode, the timer/counter is increased by one at any rising edge of internal pulse. User can choose

up to 4 types of internal pulse rate by setting IPSB for timerB (IPSA for timerA).

When timer/counter counts overflow, an interrupt request will be sent to interrupt control unit.

Internal pulse

TimerB (TimerA )value

n+1

n+2

n+3

n+4

n+5

n+6

n+7

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