Library to control Silicon Labs SI570 10 MHZ TO 1.4 GHZ I2C PROGRAMMABLE XO/VCXO.
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(); 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()); } }
Links
- NXP mbed design challenge entry: Si570-Based Universal HAM Radio VFO
- www.agri-vision.nl (home of this project)
- Experiments with software defined radio (SDR) using Softrock, the Si570 VCXO, and a hacked Linux based ADM5120 router to control the Si570, using a web browser.
- Review of Si570 Frequency Synthesizer Kit from K5JHF and K5BCQ
- DG8SAQ - Si570 control with AVR
Reference
SI570.h
- Committer:
- soldeerridder
- Date:
- 2010-11-09
- Revision:
- 0:dae1bf95c49e
File content as of revision 0:dae1bf95c49e:
/* mbed SI570 Library, for driving the SI570 programable VCXO * Copyright (c) 2010, Gerrit Polder, PA3BYA * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #ifndef MBED_SI570_H #define MBED_SI570_H #include "mbed.h" //these must be floating point number especially 2^28 so that //there is enough memory to use them in the calculation #define POW_2_16 65536.0 #define POW_2_24 16777216.0 #define POW_2_28 268435456.0 #define FOUT_START_UP 56.320 //MHz #define PPM 3500 // +/- max ppm from center frequency #define FDCO_MAX 5670.0 //MHz #define FDCO_MIN 4850.0 //MHz /** Interface to the popular SI570 VCXO */ class SI570 { public: /** Create an instance of the SI570 connected to specified I2C pins, with the specified address. * * Example: * @code * #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()); * } * } * @endcode * * @param sda The I2C data pin * @param scl The I2C clock pin * @param address The I2C address for this SI570 */ SI570(PinName sda, PinName scl, int address); /** Resets the SI570. * * Resets and reads the startup configuration from the Si570 */ void si570reset(void); /** Read the current frequency. * * get the SI570 registers an calculate the current frequency * * @returns the current frequency */ double get_frequency(void); /** Read the current rfreq value. * * get the SI570 registers an calculate the current rfreq * * @returns the current rfreq */ double get_rfreq(void); /** Read the current n1. * * get the SI570 registers an calculate the current n1 * * @returns the current n1 */ int get_n1(void); /** Read the current hsdiv. * * get the SI570 registers an calculate the current hsdiv * * @returns the current hsdiv */ int get_hsdiv(void); /** Set a new frequency. * * Set the SI570 registers to output frequency * When the new frequency is within the 3500 PPM range of the center frequency, hsdiv and n1 needs not to be reprogrammed, resulting in a glitch free transition. * For changes larger than 3500 PPM, the process of freezing and unfreezing the DCO will cause the output clock to momentarily stop and start at any arbitrary point during a clock cycle. This process can take up to 10 ms. * * @param frequency the frequency to set. * @returns the current frequency */ int set_frequency(double frequency); private: I2C _i2c; int _address; char cmd[2]; char buf[6]; unsigned char n1; unsigned char hsdiv; unsigned long frac_bits; double rfreq; double fxtal_device; double currentFreq; double currentRfreq; void get_registers(void); int set_frequency_small_change(double currentFrequency); int set_frequency_large_change(double currentFrequency); unsigned char SetBits(unsigned char original, unsigned char reset_mask, unsigned char new_val); }; #endif