DE5-NET
User
Manual
63
June 20, 2018
Figure 5-1
Si570 Block diagram
The output frequency is calculated using the following equation:
When Si570 is powered on, the default output frequency is 100 MHz. Users can program the output
frequency through the I2C interface using the following procedure.
6.
Freeze the DCO (bit 4 of Register 137).
7.
Write the new frequency configuration (RFREQ,HSDIV, and N1) to Register 7
–
12.
8.
Unfreeze the DCO and assert the NewFreq bit (bit 6 of Register 135).
The I2C address of Si570 is zero and it supports fast mode operation whose transfer rate is up to
400 kbps.
shows the register table for Si570.