Diff: SignalGenerator.h

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0:40051400cafe

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+/* mbed signal generator implementation using LPC1768 DAC
+ * Copyright (c) 2010 ygarcia
+ *
+ * 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.
+ */
+
+#if !defined(__SIGNALGERNERATOR_H__)
+#define __SIGNALGERNERATOR_H__
+
+#define __DEBUG
+#include "Debug.h"
+
+/** This class provides methods to generate differents signale wave form. V0.0.0.1
+ *
+ * Note that the maximum update rate of 1 MHz, so Fmax = 1MHz / _num_pixels
+ *
+ * Note that Vout is given by the relation below (UM10360 - Table 537. D/A Pin Description):
+ *    Vout = VALUE * ((Vrefp - Vrefn) / 1024) + Vrefn
+ *    in which:
+ *        - Vrefp: tied to VDD (e.g. 3.3V)
+ *        - Vrefn: tied to Vss
+ * @see UM10360 - Chapter 30: LPC17xx Digital-to-Analog Converter (DAC)
+ * @remark This class was validated with Tektronix TDS2014 oscilloscope
+ * @author Yann Garcia (Don't hesitate to contact me: garcia.yann@gmail.com)
+ * References:
+ * - http://fabrice.sincere.pagesperso-orange.fr/cm_electronique/projet_pic/gbf/gbf.htm
+ * @todo 1) Enhance comments 2) Add support of user-defined signal in byte array format
+ */
+class SignalGenerator
+{
+public:
+    /** List of supported signals
+     */
+    enum SignalGeneratorType {
+        SquareSignal = 0, //<! Square signal (50% duty cycle)
+        TriangleSignal = 1, //<! Triangle signal
+        SawtoothSignal = 2, //<! Sawtooth signal
+        ReverseSawtoothSignal = 3, //<! Reversed sawtooth signal
+        SinusSignal = 4 //<! Sinusoidal signal
+    }; // End of SignalGeneratorType enum
+public:
+    /** Default ctor
+     *
+     * Initialize the internal datas. Default values are:
+     * - signal type: SquareSignal
+     * - frequency: 1000Hz
+     * - # of pixels is fixed, _twait is adjusted
+     * 
+     * @param p_outPort: Pin name of the Analog out port (e.g. p18 for LPC1768)
+     */
+    SignalGenerator(PinName p_outPort);
+    /** Default dtor
+     *
+     * Free resources
+     */
+    virtual ~SignalGenerator();
+    
+    /** Set the frequency of the signal.
+     *
+     * @param p_signalType: Signal type. Default value is square signal
+     * @param p_frequency: Signal frequency. Default value is 1000Hz
+     * @param p_num_pixels: Number of pixels ber period. Default value is 64
+     * @see UM10360 - Chapter 30: LPC17xx Digital-to-Analog Converter (DAC)
+     * @code
+     * // Prepare a sinus signal at 500Hz
+     * signal.SetSignalFrequency(SignalGenerator::SinusSignal,500);
+     * // Launch execution
+     * signal.BeginRunAsync();
+     * // Here signal generation is running. Use Led or oscilloscope to vizualize output
+     * printf("Press any key to terminate");
+     * getchar();
+     * // Terminate execution
+     * signal.EndRunAsync();
+     * @endcode
+     */
+    void SetSignalFrequency(SignalGenerator::SignalGeneratorType p_signalType = SignalGenerator::SquareSignal, int p_frequency = 1000, int p_num_pixels = 64);
+    /** Generate the signal in synchrnous mode
+     *
+     * @see Stop() method
+     */
+    void Run();
+    /** Method called to terminate synchronous running mode
+     */
+    void Stop();
+    /** Method called to prepare an asynchronous running mode
+     *
+     * @return 0 on success, -1 if _twait less that 7us. On error, you shall use synchronous method
+     */
+    int BeginRunAsync();
+    /** Method called to launch the asynchronous running mode
+     */
+    void RunAsync();
+    /** Method called to terminate asynchronous running mode
+     */
+    void EndRunAsync();
+
+    SignalGenerator& operator =(const bool& p_mode);
+    SignalGenerator& operator =(const int& p_frequency);
+    SignalGenerator& operator =(const SignalGenerator::SignalGeneratorType& p_signalType);
+private:
+    /** Set the signal type to generate and build the lookup table according to the signal frequency.
+     */
+    void PrepareSignal();
+    /** Build the lookup table for a square signal according to the signal frequency.
+     *
+     * Note that the duty cycle is 50%. For different values, please refer to PwmOut class
+     */
+    void PrepareSquareSignal();
+    /** Build the lookup table for a triangle signal according to the signal frequency.
+     */
+    void PrepareTriangleSignal();
+    /** Build the lookup table for a reverse sawtooth signal according to the signal frequency.
+     */
+    void PrepareSawtoothSignal();
+    /** Build the lookup table for a sawtooth sinal according to the signal frequency.
+     */
+    void PrepareReverseSawtoothSignal();
+    /** Build the lookup table for a 'sinus' sinal according to the signal frequency.
+     */
+    void PrepareSinusSignal();
+private:
+   SignalGenerator::SignalGeneratorType _signalType; //<! Signal selected - Default value is SquareSignal
+   int _frequency; // Required frequency of the signal
+   float *_values; //<! Pointer to the array of calculated values for the selected signal
+   int _num_pixels; // <! Number of calculated points, this is the _values length
+   float _twait; //<! Time between each changes of the analog output
+   bool _mode; //<! # of pixels is fixed (128 pixels)
+   AnalogOut _out; //<! Analog out pin of the LPC1768
+   bool _stop; //<! Set to tru to stop the signal generation
+   int _asynckCounter; //<! Index on _values when asynchronous run is used
+   Ticker _asyncTicker; //<! Ticker to ipdate DAC when asynchronous run is used
+   DigitalOut _debugLed; //<! For debug with oscilloscope purpose
+}; // End of class SignalGenerator
+  
+#endif // __SIGNALGERNERATOR_H__