GMS81C2020 Datasheet, PDF(53/92 Page) Hynix Semiconductor – CMOS Single-Chip 8-Bit Microcontroller with A/D Converter & VFD Driver

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GMS81C2020 Datasheet, PDF (53/92 Pages) Hynix Semiconductor – CMOS Single-Chip 8-Bit Microcontroller with A/D Converter & VFD Driver

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Hyundai Micro Electronics

GMS81C2020/GMS81C2120

These timers have each 8-bit count register and data regis-

ter. The count register is increased by every internal or ex-

ternal clock input. The internal clock has a prescaler divide

ratio option of 2, 4, 8, 32,128, 512, 2048 (selected by con-

trol bits T0CK2, T0CK1 and T0CK0 of register TM0) and

1, 2, 8 (selected by control bits T1CK1 and T1CK0 of reg-

ister TM1). In the Timer 0, timer register T0 increases

from 00H until it matches TDR0 and then reset to 00H. The

match output of Timer 0 generates Timer 0 interrupt

(latched in T0IF bit). As TDRx and Tx register are in same

address, when reading it as a Tx, written to TDRx.

In counter function, the counter is increased every 0-to-

1(1-to-0) (rising & falling edge) transition of EC0 pin. In

order to use counter function, the bit EC0 of the R0 Func-

tion Selection Register (R0FUNC.2) is set to "1". The Timer

0 can be used as a counter by pin EC0 input, but Timer 1

can not.

TDR1

Timer 1 (T1IF)

Interrupt

n-1

up-count

PCP

Interrupt period

= PCP x (n+1)

Occur interrupt

Figure 15-3 Counting Example of Timer Data Registers

TIME

TDR1

Timer 1 (T1IF)

Interrupt

T1ST

Start & Stop

T1CN

Control count

clear & start

stop

disable enable

up-count

Occur interrupt

T1ST = 0

T1ST = 1

T1CN = 0

T1CN = 1

Figure 15-4 Timer Count Operation

TIME

Nov. 1999 Ver 0.0

preliminary

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