System information

6 Hardware Monitor Functionality
onboard ADC measures the related change of the voltage between the NTC and a constant
reference resistor. The temperature is calculated by two steps. First, the measured voltage is
converted into the related resistance of the NTC. Afterwards, the temperature is calculated
by the resistance of the NTC using the Steinhart & Hart equation [81, 82].
Port Usage
1 Voltage measurement of 12V PCI pin.
2 Temperature measurement using an external NTC.
3 Temperature measurement using an external NTC.
4 Temperature measurement of the CHARM board.
5 - 10 Temperature measurement using an external NTC.
11 Voltage measurement of 3.3V PCI pin.
12 Voltage measurement of 5V PCI pin.
Table 6.1: Usage of the ADC ports.
FAN Speed Measurement
The CHARM card provides also the speed measurement of up to eight cooling fans. The
fans should be connected to the board of the card. The fan_speed VHDL module counts the
fan speed impulses in a fixed period of time. The results can be obtained by the CHARM
register file. The program fan_speed shows a list of all measured speed values. Following a
sample output of the program:
charm:/ $ fan_speed
Fan 1 rotation speed = 3159 RPM
Fan 2 rotation speed = 2344 RPM
Fan 3 rotation speed = 738 RPM
Fan 4 rotation speed = 745 RPM
Fan 5 rotation speed = 0
Fan 6 rotation speed = 0
Fan 7 rotation speed = 0
Fan 8 rotation speed = 0
6.3 Display Screen Inspector
One advantage of the CHARM is the integrated VGA function. With the aid of the VGA
driver, one has direct access to the VGA planes (see section 4.2.3). The VGA data can
be inspected before it will be generated to a video output signal. This approach permits
several powerful features of the CHARM: obtaining the textual representation of the screen
and inspecting previous screen contents. Section 6.3.1 explains the generation of the textual
representation of the screen content and section 6.3.2 illustrates how to get the previous
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