Gerrit Polder / SI570

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

Dependents:   t2d Thing2Do

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Table of Contents

  1. Image of the SI570 in action
  2. Hello World!
  3. Links
  4. Reference

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

/media/uploads/soldeerridder/si570_sr.jpg

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();
         freq=startfreq+wp*0.00001;
         if (swp != wp) {
             si570.set_frequency(freq);
             swp = wp;
         }                
         lcd.locate(0,0);
         lcd.printf("%f MHz", si570.get_frequency());
     }
 }

Reference

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