Altera Audio Video Development Kit, Stratix IV GX Edition - Manual (Page 48)

6–26 Chapter 6: Board Test System
The Clock Control
Audio Video Development Kit, Stratix IV GX Edition User Guide © November 2009 Altera Corporation
The following sections describe the Clock Control controls.
Serial Port Registers
The Serial port registers control shows the current values from the Si570 registers.
f For more information about the Si570 registers, refer to the Si570/Si571 datasheet
available on the Silicon Labs website (
www.silabs.com ).
fXTAL
The fXTAL control shows the calculated internal fixed-frequency crystal based on the
serial port register values.
f For more information about the f
XTAL
value and how it is calculated, refer to the
Si570/Si571 datasheet available on the Silicon Labs website ( www.silabs.com ).
Disable Oscillator
The Disable oscillator enables and disables the Si570 output buffer. Turn on Disable
oscillator
to power down the Si570 output buffer. Turn off the Disable oscillator to
drive the Si570 output buffer normally.
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.
Figure 6–13. The Clock Control