UPD17708 datasheet(164/356 Pages) NEC

164 / 356 page

µPD17704, 17705, 17707, 17708, 17709

164

13.3.2 Clock selection, start/stop control, and gate control blocks

Figure 13-12 shows the configuration of these blocks.

The clock selection block selects a basic clock to operate timer 0 counter.

Four types of basic clocks can be selected by using the TM0CK1 and TM0CK0 flags.

Figure 13-13 shows the configuration and function of each flag.

The start/stop block controls the TM0MD flag and open/close signal from the gate control block, and starts

or stops the basic clock to be input to timer 0 counter by the TM0EN flag.

The gate control block sets the opening or closing conditions of the gate.

It sets whether the gate is opened or closed by a rising or falling of the input signal, by using the TM0GOEG

and TM0GCEG flags. This block also issues an interrupt request when the closing condition of the gate is

detected.

Figure 13-14 shows the configuration and function of each flag.

Figure 13-12. Configuration of Clock Selection, Start/Stop Control, and Gate Control Blocks

Selector

100 kHz

10 kHz

2 kHz

1 kHz

TM0CK1

TM0CK0

Clock selection

Divider

4.5 MHz

Start/stop

Timer 0 counter

TM0EN flag

TM0MD flag

P1A0/TM0G

TM0GOEG

TM0GCEG

Gate control

Open/

Edge

detection

Timer 0 interrupt

UPD17708 데이터시트(PDF) 164 Page - NEC