Datascope Passport 2, Руководство по обслуживанию

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Passport 2®/Passport 2 LT™ Service Manual 0070-10-0441 2 - 7
Theory of Operation CPU Control Module
2.1.12 Tone Generator, U39
The tone generator is implemented using an eight bit microcontroller. The device generates a
tone signal of 909Hz for a duration of 300ms. The tone is generated in response to the
following input conditions:
1. When the system is first turned on, the level of the MPC860T's BRESET* (same as
HRESET*) signal is monitored. If this level is detected as high, the tone is generated.
2. When an active low status signal input is detected, the tone is generated. The status
signal tone 769Hz for a duration of 300ms is generated by the MPC860T on Port A, bit
4 (PA4). The signal can be repeated as required in order to create a series of tones.
2.1.13 LCD/CRT VGA Controller, U16
The LCD/VGA controller is a SPC8110 with an integrated RAMDAC, PLL Bit Block Transfer
engine and a VL Local Bus interface. It is capable of displaying 256 colors. Support for video
modes of 640 X 480 and 800 X 600 is required. The display controller needs to be able to
drive a TFT color LCD (10.4" or 12.1") (single scan), or EL panel (dual scan), or
Monochrome LCD Passive (dual scan) and an external VGA color CRT simultaneously.
The display system consists of the LCD/CRT VGA controller (U16), clock oscillator (U65), the
programmable clock synthesizer (Y2 & U66), and video display RAM (U18 & U19). The
signals required by the various display panels are routed to the Keypad/Display board
through connector J5. The various Keypad/Display boards have specific interface connectors
for each display type, requiring only a simple one-to-one cable assembly. The display panel
identifies itself to the CPU module by connecting selected pins in the VIDSEL[4:1] field
directly to the power net. These signals are pulled down to 3VGND on the CPU module
through 33.2K resistors, and their assigned value is then read, in order to identify the panel
type.
2.1.14 PCMCIA Interface
The PCMCIA interface is a dual interface called Socket A and Socket B. The PCMCIA cards
plug into a dual stacked connector assembly, J14. The MPC860T's PCMCIA host adapter
module provides all the control logic for each PCMCIA socket interface and requires only
power switching logic and buffering. The additional external buffering allows the PCMCIA
host adapter module to support up to two PCMCIA sockets and provide electrical isolation.
Because the PCMCIA interface specification was designed around the Intel (Little Endian)
method of storing 16 bit words, a byte swapping scheme had to be employed in order to
conform to the standard. Motorola follows the Big Endian method.
2.1.15 Serial EEPROM
The memory is made up of 512 bytes of non-volatile memory. U45 is a dip part and is
socketed to allow programming the memory with an external programmer. This device is
used to store network settings. Communications from the device is done via the MPC860T's
SPI interface. To select this SPI device the MPC860T's, SPISEL signal (PB31) should be set to
logic '0'.