UPD17P136ACT datasheet(141/292 Pages) NEC

141 / 292 page

CHAPTER 13 PERIPHERAL HARDWARE

122

13.2 BASIC INTERVAL TIMER (BTM)

The

µPD17134A subseries has a 7-bit basic interval timer.

This basic interval timer has the following functions.

(1) Generates reference time.

(2) Selects and counts wait time when standby mode is released.

(3) Serves as watchdog timer that detects program hang-up.

13.2.1 Basic Interval Timer Configuration

Figure 13-9 shows the configuration of the basic interval timer.

Figure 13-9. Basic Interval Timer Configuration

Remark (1) through (4) in the figure corresponding to the signals in the timing chart in Figure 13-12.

BTM mode

Watchdog timer

mode register

(RF: 03H)

BTMISEL BTMRES BTMCK1 BTMCK0

WDTRES 0

WDTEN

Reset

Selector

fX/8192

fX/4096

Timer 0 count up

INT pin (ACZCROSS)

Basic interval timer

(7-bit divider circuit)

Reset

Selector

IRQBTM

set signal

Watchdog

reset signal

(3)

(2)

Outputs 1 while counting 0 to 7

during count of 0 to 256

fBTM

1-bit

divider

circuit

1-shot pulse

generation

circuit

Internal bus

(4)

(1)

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