Library to control Silicon Labs SI570 10 MHZ TO 1.4 GHZ I2C PROGRAMMABLE XO/VCXO.

Dependents:   t2d Thing2Do

This is the page for the Silicon Laboratories Si570 frequency synthesizer, with I2C interface.

The Si570 XO/Si571 VCXO utilizes Silicon Laboratories’ advanced DSPLL® circuitry to provide a low-jitter clock at any frequency. The Si570/Si571 are user-programmable to any output frequency from 10 to 945 MHz and select frequencies to 1400 MHz with <1 ppb resolution. The device is programmed via an I2C serial interface. Unlike traditional XO/VCXOs where a different crystal is required for each output frequency, the Si57x uses one fixed- frequency crystal and a DSPLL clock synthesis IC to provide any-frequency operation. This IC-based approach allows the crystal resonator to provide exceptional frequency stability and reliability. In addition, DSPLL clock synthesis provides superior supply noise rejection, simplifying the task of generating low-jitter clocks in noisy environments typically found in communication systems.

The Si570 is very popular for amateur radio use. It can be used as the local oscillator in a superheterodyne receiver, or it can be the local oscillator in a direct conversion quadrature receiver for software defined radio (SDR) such as the Softrock. In addition to its use inside a receiver, the Si570 kit can be used as a stand-alone signal source for test and measurement and for other purposes, such as a VFO for your old Heathkit DX40 for that matter. Just keep in mind that the Si570's output is a square wave and may require additional filtering for some purposes.

Image of the SI570 in action


Hello World!

 #include "mbed.h"
 #include "TextLCD.h"
 #include "SI570.h"
 #include "QEI.h"
 TextLCD lcd(p11, p12, p15, p16, p29, p30); // rs, e, d0-d3
 SI570 si570(p9, p10, 0xAA);
 QEI wheel (p5, p6, NC, 360);
 int main() {
     int wp,swp=0;
     float startfreq=7.0;
     float freq;
     while (1) {
         wp =  wheel.getPulses();
         if (swp != wp) {
             swp = wp;
         lcd.printf("%f MHz", si570.get_frequency());



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SI570.cpp 9780 Revisions Annotate
SI570.h 5018 Revisions Annotate