Mindray TRIO Manual de servicio descargar pdf (Pagina 18)

Trio™ Service Manual 0070-10-0591-01 1 - 11

Theory of Operation Hardware Overview

1.2.6 Keypad Board

P/N 0671-00-0064

FIGURE 1-8 Keypad block diagram

1.2.6.1 Detailed Description

This module detects keypad and encoder input signals, converts them into code and transmits

the code to the Host CPU board. The Host CPU board sends commands to the keyboard

which in turn controls the indicator and audio process circuits, activating audio and visual

alarms accordingly.

CPU

The Keypad Board's CPU is responsible for the following functions:

• Detects keypad and encoder input signals

•Controls LED status

• Controls Audio Process Circuit

• Regularly zeroes Watchdog Timer

• Communicates with main board.

Key Test Points

NO. NAME LOCATION FUNCTION

1 VCC P4.4 Power input, range: 4.8~5.2V

2 GND P4.5 Power supply and signal ground

3 RST U1.10 CPU reset signal. At low level(<0.3V) when

operating normally

4 Crystal oscillator X1.1,X.2 CPU crystal oscillator. Sine wave signal

(1.5~3.5V) when operating normally

Watchdog

ENCODER

KEY

CPU

(PIC16F73)

RAM

192 X 8

FLASH

4K X 4

Main Control

board (Host CPU Board)

Audio Process

Circuit

SPEAKER

LED

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 ... 81 82

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Mindray TRIO Manual de servicio Pagina 18