Digital Schematic Figure 17-5 Through Figure 17-7 - Mallinckrodt NELLCOR NPB-4000 Service Manual

13.16 DIGITAL SCHEMATIC FIGURE 17-5 THROUGH FIGURE 17-7

Section 13: Microprocessor Computer and Control –Theory of Operation
Register CS5# + E has the following bit assignments
Bit 0 Not used
BIT 1 Not used
BIT 2 Not used
BIT 3 Not used
BIT 4 Not used
BIT 5 NURSE CALL
BIT 6 PRINTER RESET
BIT 7 PRINTER CTS (CLEAR TO SEND)
The NURSECALL and PRINTER RESET bits are the flip flop outputs
programmed by writing to register CS5# + E as explained above.
A 1 (high) indicates that the bit is true, a 0 that the bit is false.
These schematics include all of the above circuits and some additional circuits
that need explanation. For clarity purposes we will discuss the page 1 and
integrate page 2 wherever necessary.
Page 1 of the schematics is mostly the digital portion of the design. It contains
the following chips:
386EXMP
ACT1000F
LCD
CONTROLLER
74HCT244
74LVC16245
RTC DS1693
74LVC541
DUART
MAX211E
DISPLAY RAM
DRAM
74ACT157
BOOT FLASH
TREND FLASH
OSCILLATOR
microcontroller
programmable device with the control circuits
1351FLB LCD display control chip
buffer chips for the signals from the LCD
controller to the display itself
data bus buffer to interface the 386EX to the other
chips
real-time clock with 64 bytes of battery-backed
ram and on-board crystal
mux for the address/data to the RTC
dual UART for the RS-232 and recorder
RS-232 interface chip with 15,000 volts ESD
32K x 8 SRAM for the LCD display
256K x 16 dynamic ram memory
address mux for the DRAM
bootable/executable flash memory
flash memory for storing trend data
40 MHz oscillator to generate CLK2
13-23