Altera Cyclone V SoC User Manual download pdf (Page 36)

5–18 Chapter 5: Board Test System

The Clock Control

Cyclone V SoC Development Kit November 2013 Altera Corporation

User Guide

The Clock Control communicates with the MAX V device on the board through the

JTAG bus. The Si570 and Si571 programmable oscillators are connected to the MAX V

device through a 2-wire serial bus. Figure 5–9 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.

f For more information about the Si570 registers, refer to the Si570/Si571 data sheet

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.

For more information about the f

XTAL

value and how it is calculated, refer to the

Si570/Si571 data sheet available on the Silicon Labs website (www.silabs.com).

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.

Figure 5–9. The Clock Control

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Altera Cyclone V SoC User Manual Page 36