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5.5. The Clock Control
The Clock Control application runs as a stand-alone application. ClockControl.bat resides in the cycloneVSX_5csxfc6df31_soc\examples\board_test_system directory.
For more information about the Si570/Si571/Si5338 and the Cyclone® V development board's clocking circuitry and clock input pins, refer to the Cyclone® V SoC Development Board Reference Manual .
The Clock Control communicates with the MAX® V device on the board through the JTAG bus. The Si570, Si571, and Si5338 programmable oscillators are connected to the MAX® V device through a 2-wire serial bus.
The following figure shows the Clock Control Si570 tab.
The following sections describe the Clock Control controls.
Serial Port Registers
The Serial port registers control shows the current values from the Si570 registers.
For more information about the Si570 registers, refer to the Si570/Si571 data sheet available on the Skyworks website.
fXTAL
The fXTAL control shows the calculated internal fixed-frequency crystal, based on the serial port register values. For more information about the fXTAL value and how it is calculated, refer to the Si570/Si571 data sheet available on the Skyworks website.
Target Frequency
The Target frequency control allows you to specify the frequency of the clock. Legal values are between 10 and 810 MHz with eight digits of precision to the right of the decimal point. For example, 421.31259873 is possible within 100 parts per million (ppm). The Target frequency control works in conjunction with the Set New Frequency control.
Default
This control sets the frequency for the oscillator associated with the active tab back to its default value. This can also be accomplished by power cycling the board.
Set New Frequency
The Set New Frequency control sets the programmable oscillator frequency for the selected clock to the value in the Target frequency control for the Si570 and Si571. Frequency changes might take several milliseconds to take effect. You might see glitches on the clock during this time. Altera recommends that you reset the FPGA logic after changing the frequencies.