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SECTION 14: MAIN COLOR BOARD DIGITAL THEORY OF
OPERATION
14. MAIN COLOR BOARD DIGITAL THEORY OF OPERATION
14.1 GENERAL
14.1 General
14.2 Power Supply Connections
14.3 CPU Connections
14.4 LNA 386EX Connections
14.5 CPU Timing
14.6 Dram Control
14.7 Flash Control
14.8 LCD Display
14.9 Real Time Clock (RTC)
14.10 DUART Control
14.11 Knob Interface Control
14.12 Push Button Control
14.13 Miscellaneous Control - CS5#
14.14 Speaker
14.15 NIBP (Non Invasive Blood Pressure) Control
14.16 Front End Interface
14.17 Digital Schematic
14.18 Block Diagram
14.19 Current Drain of Digital Electronics
The LNA color digital design is based around an Intel 386EX microcontroller,
which has a 386SX microprocessor core and peripheral blocks around it. The
internal peripherals are all controlled by on board programmable registers. In
order to save power this design has a Vcc = 3.3 volts.
The data from the front end (ECG, temperature, respiration, etc.) is multiplexed
through a linear opto isolator to a 12 bit A/D converter, which is connected to
the on board synchronous serial port. The synchronous serial port is controlled
by the on board DMA unit.
The LCD display is a 640x480 TFT color display which is connected to an
S-MOS 1354F0A controller chip. This chip interfaces via the data bus to the
386EX and has one 1MX16 DRAM for data storage. The backlight is controlled
by enabling the +12 volts DC to the inverter board. There is no contrast
adjustment for this display.
The main executable memory is a 512Kx16 flash memory which takes the upper
1Megabyte of address space. This flash contains the boot program and the
executable program for controlling the whole unit.
A 2 Megabyte DRAM is located in lower memory starting at location 0 and is
used for data storage and manipulation. The DRAM also has the ability to
execute code when programming the flash with a new program from the external
RS-232 port.
14-1
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Table of Contents
Troubleshooting
