System Management Devices And Functions - Rastergraf Topaz User Manual

5.5 System Management Devices and Functions

The Topaz/Stratus/Garnet boards have devices that are specifically
intended to assist in system management. These include:
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Please contact Rastergraf for more information if you wish to utilize any
or all of these features.
A National Semiconductor LM75 I
near the SM731 chip provides local temperature measurements.
You can obtain the data sheet and collateral information for the
LM75 from the technical document section on the Rastergraf web
site;
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A 2 Kb I C Serial EEPROM which can be used by system software
to store data such as serial number and software revision;
In addition, there are features of the SM731 chip that are useful:
Power management control registers allow various parts of the
chip to be put powered down without making the chip entirely
useless;
Signature registers in the RAMDAC can be are used to confirm
that a test pattern in display memory will pass correctly through
the SM731 all the way to the DAC inputs. This is useful as a Built
In Self Test (BIST) function;
When the board is properly connected to a monitor and a test
image is displayed on the monitor, a certain level voltage will be
developed at the DAC outputs that drive the monitor. A simple
A/D reads the voltage and confirms that the DAC output is above a
certain threshold level;
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The I C-based DDC2B protocol is used to control the display
monitor. DDC2B is a VESA standard (http://www.vesa.org/)
which allows the frame buffer to read the Additional Display
Identification Data (EDID) from the monitor. The EDID includes
resolutions supported, maximum width and refresh, and sync type;
Frequency select bits for the SM731 Drawing Engine and the
programmable Memory Clock PLL allow the system to optimize
operating frequencies for the SM731 as a function of system
temperature.
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C temperature sensor located
Programming On-board Devices and Memories 5-19
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