W742E816 Просмотр технического описания (PDF) - Winbond

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W742E816

4-BIT MICROCONTROLLER

Winbond 

W742E/C816

Deleted: SA5505

Deleted: W742C811

5.12 Timer/Counter

5.12.1 Timer 0 (TM0)

Timer 0 (TM0) is a programmable 8-bit binary down-counter. The specified value can be loaded into

TM0 by executing the MOV TM0L(TM0H), R instructions. When the MOV TM0L(TM0H), R instructions

are executed, it will stop the TM0 down-counting (if the TM0 is down-counting) and reset the MR0.3 to

0, and the specified value can be loaded into TM0. Then we can set MR0.3 to 1, that will cause the

event flag 1 (EVF.1) is reset and the TM0 starts to down count. When it decrements to FFH, Timer 0

stops operating and generates an underflow (EVF.1 = 1). Then, if the Timer 0 interrupt enable flag has

been set (IEF.1 = 1), the interrupt is executed, while if the hold release enable flag 1 has been set

(HEF.1 = 1), the hold state is terminated. The Timer 0 clock input can be set as FOSC/1024 or FOSC/4

by setting MR0 bit 0. The default timer value is FOSC/4. The organization of Timer 0 is shown in Figure

5-6.

If the Timer 0 clock input is FOSC/4:

Desired Timer 0 interval = (preset value +1) × 4 × 1/FOSC

If the Timer 0 clock input is FOSC/1024:

Desired Timer 0 interval = (preset value +1) × 1024 × 1/FOSC

Preset value: Decimal number of Timer 0 preset value

FOSC: Clock oscillation frequency

Fosc/1024

Fosc/4

1. Reset

2. CLR EVF, #02H

3. Reset MR0.3 to 0

4. MOV TM0L, R or MOV TM0H, R

MR0.0

Disable

Enable

Set MR0.3 to 1

8-Bit Binary

Down Counter

(Timer 0)

4

4

MOV TM0H, R MOV TM0L, R

SQ

R

EVF.1

HEF.1

IEF.1

Hold mode release (HCF.1)

Timer 0 interrupt (INT1)

1. Reset

2. CLR EVF, #02H

3. Set MR0.3 to 1

Figure 5-6 Organization of Timer 0

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Publication Release Date: April 15, 2005

Revision A2

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