Service manual

UCW and Ultraview 1700 Monitors — Service Manual
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EMI Reduction
The CPU PCBA includes several design features intended to reduce EMI effects. The power supply
to the PCBA is segmented and heavily filtered to prevent noise propagation from one part of the
PCBA to another. All high-frequency signals are driven through series resistors to limit the rise and
fall times of these signals, reducing ringing and other EMI effects. The construction of the multi-layer
PCBA is such that noisy signals are shielded by power and ground planes.
Boot Sequence Overview
When power is applied, the unit begins the boot up sequence. The following is a highly-abbreviated
version of the sequence of events that occurs while the unit is booting.
1. Program execution starts at address 00000100 in flash memory.
2. Key internal and external devices and memories are mapped and enabled.
3. The boot-type value is read from super-cap-backed SRAM. This value is written to SRAM at
every power down or self-reboot. The value determines the kind of boot, either warm or cold.
Warm booting skips diagnostics and other steps in order to boot as quickly as possible.
4. Key areas of DRAM are tested (cold boot only).
5. The boot code is copied from flash memory to DRAM and program execution resumes in
DRAM.
6. More internal and external devices are initialized.
7. Other key memory and CPU tests are performed (cold boot only).
8. The VxWorks kernel is started.
9. Drivers needed for diagnostics and the boot console are installed.
10. Diagnostics are run (cold boot only).
11. Boot logo and the 3-2-1 countdown are displayed (cold boot only).
12. The application code is copied from flash memory to DRAM and executed in DRAM.
13. Much of the above initialization is repeated as part of the application code.
14. The main monitor task, MonitorInit, is spawned and normal monitor operation begins.
Normal Operation Overview
During normal operation, the software does the following:
• Once the unit is booted, it begins normal monitor operation, which involves high-level software
subsystem tasks running simultaneously. These tasks interface to other tasks, and all tasks
interface to hardware devices via device drivers. The VxWorks kernel is responsible for running
tasks based on their relative priority and on other system interrupts and events.
Main Subsystems and Tasks:
• The SDLC subsystem sends packets from the modules to the rest of the system, including
Ethernet and GDS, and sends packets to modules.
• The Interpreter subsystem provides modules and keys with “primitives” that are used via table
code to create and control the display and action of the various menus and keys. The Interpreter
subsystem processes key presses from the user and notifies the Keyboard Interpreter to execute
the appropriate table code program. That program uses the Key Display task to redraw the new
key state as feedback to the user.