Service manual

CARDELL MONITOR SERVICE MANUAL

21-02-0286 REV. 02 05/09

Keypad Monitoring

The keypad comes into the Main Control Board at J6. There are eight keys are read as inputs

by the DSP (U20 pins 116 - 124). The keys are normally high and active low when the switch is

pressed.

Indicator LED’S and Displays

U11, U13, U14, U15 and U16 are seven segment LED driver IC’s that are controlled thru the

SPI port of the DSP (U20). They are used to display Systolic, Diastolic, MAP, %SpO

, BPM,

SpO

bar graph, LARGE CUFF led, SMALL CUFF led, Silence led and the two slash led’s. U12

is an eight character smart alphanumeric display (Message Window) that is driven by the DSP

(U20) directly.

Real-Time Clock

The real-time clock (U21) is controlled by the DSP (U20) thru the SPI port. The part has it own

battery and internal crystal. The battery can be replaced separately when needed.

Alarms

The alarms circuit has an audio attenuator (U23), an amplifier (U24) and a speaker (LS1). The

sound is controlled by the DSP (U20).

Serial Interface

The serial input/output goes into the Main Control Board on J10. The serial port is controlled by

the DSP (U20).

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