Altera Audio Video Development Kit, Stratix IV GX Edition - Manual (Page 47)

Chapter 6: Board Test System 6–25
The Clock Control
© November 2009 Altera Corporation Audio Video Development Kit, Stratix IV GX Edition User Guide
Calculating Power
The Power Monitor calculates power by measuring two different voltages with the
LT2418 A/D and applying the equation P = V × I to determine the power
consumption. The LT2418 measures the voltage after the appropriate sense resistor
(Vsense) and the voltage drop across that sense resistor (Vdif). The current (I) is
calculated by dividing the measured voltage drop across the resistor by the value of
the sense resistor (I = Vdif/R). Through substitution, the equation for calculating
power becomes P = V × I = Vsense × (Vdif/R) = (Vsense) × (Vdif) × (1/.003).
You can verify the power numbers shown in the Power Monitor with a digital
multimeter that is capable of measuring microvolts to ensure you have enough
significant digits for an accurate calculation. Measure the voltage on one side of the
resistor (the side opposite the power source) and then measure the voltage on the
other side. The first measurement is Vsense and the difference between the two
measurements is Vdif. Plug the values into the equation to determine the power
consumption.
The Clock Control
The Clock Control sets the Si570 programmable oscillator to any frequency between
10 MHz and 810 MHz with eight digits of precision to the right of the decimal point.
The oscillator drives a 2-to-4 buffer that drives a copy of the clock to all four edges of
the FPGA.
The Clock Control runs as a stand-alone application. ClockControl.exe resides in the
<install dir>\kits\stratixIVGX_4sgx230_av\examples\board_test_system directory.
On Windows, click Start > All Programs > Altera > Audio Video Development Kit,
Stratix IV GX Edition
<version> > Clock Control to start the application.
f For more information about the Si570 and the Stratix IV GX development board’s
clocking circuitry and clock input pins, refer to the
Stratix IV GX FPGA Development
Board Reference Manual .
The Clock Control communicates with the MAX II device on the board through the
JTAG bus. The Si570 programmable oscillator is connected to the MAX II device
through a 2-wire serial bus.
Figure 6–13 shows the Clock Control.