Diff: SI570.h

Revision:

0:dae1bf95c49e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SI570.h	Tue Nov 09 20:56:52 2010 +0000
@@ -0,0 +1,150 @@
+/* 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
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