SignalGenerator.h

00001 /* mbed signal generator implementation using LPC1768 DAC
00002  * Copyright (c) 2010 ygarcia
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020  * THE SOFTWARE.
00021  */
00022 
00023 #if !defined(__SIGNALGERNERATOR_H__)
00024 #define __SIGNALGERNERATOR_H__
00025 
00026 #include "Debug.h"
00027 
00028 /** This class provides methods to generate differents signale wave form. V0.0.0.2
00029  *
00030  * Note that the maximum update rate of 1 MHz, so Fmax = 1MHz / _num_pixels
00031  *
00032  * Note that Vout is given by the relation below (UM10360 - Table 537. D/A Pin Description):
00033  *    Vout = VALUE * ((Vrefp - Vrefn) / 1024) + Vrefn
00034  *    in which:
00035  *        - Vrefp: tied to VDD (e.g. 3.3V)
00036  *        - Vrefn: tied to Vss
00037  * @see UM10360 - Chapter 30: LPC17xx Digital-to-Analog Converter (DAC)
00038  * @remark This class was validated with Tektronix TDS2014 oscilloscope
00039  * @author Yann Garcia (Don't hesitate to contact me: garcia.yann@gmail.com)
00040  * References:
00041  * - http://fabrice.sincere.pagesperso-orange.fr/cm_electronique/projet_pic/gbf/gbf.htm
00042  * @todo 1) Enhance comments 2) Add support of user-defined signal in byte array format
00043  */
00044 class SignalGenerator
00045 {
00046 public:
00047     /** List of supported signals
00048      */
00049     enum SignalGeneratorType {
00050         SquareSignal = 0, //<! Square signal (50% duty cycle)
00051         TriangleSignal = 1, //<! Triangle signal
00052         SawtoothSignal = 2, //<! Sawtooth signal
00053         ReverseSawtoothSignal = 3, //<! Reversed sawtooth signal
00054         SinusSignal = 4 //<! Sinusoidal signal
00055     }; // End of SignalGeneratorType enum
00056 public:
00057     /** Default ctor
00058      *
00059      * Initialize the internal datas. Default values are:
00060      * - signal type: SquareSignal
00061      * - frequency: 1000Hz
00062      * - # of pixels is fixed, _twait is adjusted
00063      * 
00064      * @param p_outPort: Pin name of the Analog out port (e.g. p18 for LPC1768)
00065      */
00066     SignalGenerator(PinName p_outPort);
00067     /** Default dtor
00068      *
00069      * Free resources
00070      */
00071     virtual ~SignalGenerator();
00072     
00073     /** Set the frequency of the signal.
00074      *
00075      * @param p_signalType: Signal type. Default value is square signal
00076      * @param p_frequency: Signal frequency. Default value is 1000Hz
00077      * @param p_num_pixels: Number of pixels ber period. Default value is 64
00078      * @see UM10360 - Chapter 30: LPC17xx Digital-to-Analog Converter (DAC)
00079      * @code
00080      * // Prepare a sinus signal at 500Hz
00081      * signal.SetSignalFrequency(SignalGenerator::SinusSignal,500);
00082      * // Launch execution
00083      * signal.BeginRunAsync();
00084      * // Here signal generation is running. Use Led or oscilloscope to vizualize output
00085      * printf("Press any key to terminate");
00086      * getchar();
00087      * // Terminate execution
00088      * signal.EndRunAsync();
00089      * @endcode
00090      */
00091     void SetSignalFrequency(SignalGenerator::SignalGeneratorType p_signalType = SignalGenerator::SquareSignal, int p_frequency = 1000, int p_num_pixels = 64);
00092     /** Generate the signal in synchrnous mode
00093      *
00094      * @see Stop() method
00095      */
00096     void Run();
00097     /** Method called to terminate synchronous running mode
00098      */
00099     void Stop();
00100     /** Method called to prepare an asynchronous running mode
00101      *
00102      * @return 0 on success, -1 if _twait less that 7us. On error, you shall use synchronous method
00103      */
00104     int BeginRunAsync();
00105     /** Method called to launch the asynchronous running mode
00106      */
00107     void RunAsync();
00108     /** Method called to terminate asynchronous running mode
00109      */
00110     void EndRunAsync();
00111 
00112     SignalGenerator& operator =(const bool& p_mode);
00113     SignalGenerator& operator =(const int& p_frequency);
00114     SignalGenerator& operator =(const SignalGenerator::SignalGeneratorType& p_signalType);
00115 private:
00116     /** Set the signal type to generate and build the lookup table according to the signal frequency.
00117      */
00118     void PrepareSignal();
00119     /** Build the lookup table for a square signal according to the signal frequency.
00120      *
00121      * Note that the duty cycle is 50%. For different values, please refer to PwmOut class
00122      */
00123     void PrepareSquareSignal();
00124     /** Build the lookup table for a triangle signal according to the signal frequency.
00125      */
00126     void PrepareTriangleSignal();
00127     /** Build the lookup table for a reverse sawtooth signal according to the signal frequency.
00128      */
00129     void PrepareSawtoothSignal();
00130     /** Build the lookup table for a sawtooth sinal according to the signal frequency.
00131      */
00132     void PrepareReverseSawtoothSignal();
00133     /** Build the lookup table for a 'sinus' sinal according to the signal frequency.
00134      */
00135     void PrepareSinusSignal();
00136 private:
00137    SignalGenerator::SignalGeneratorType _signalType; //<! Signal selected - Default value is SquareSignal
00138    int _frequency; // Required frequency of the signal
00139    float *_values; //<! Pointer to the array of calculated values for the selected signal
00140    int _num_pixels; // <! Number of calculated points, this is the _values length
00141    float _twait; //<! Time between each changes of the analog output
00142    bool _mode; //<! # of pixels is fixed (128 pixels)
00143    AnalogOut _out; //<! Analog out pin of the LPC1768
00144    bool _stop; //<! Set to tru to stop the signal generation
00145    int _asynckCounter; //<! Index on _values when asynchronous run is used
00146    Ticker _asyncTicker; //<! Ticker to ipdate DAC when asynchronous run is used
00147    DigitalOut _debugLed; //<! For debug with oscilloscope purpose
00148 }; // End of class SignalGenerator
00149   
00150 #endif // __SIGNALGERNERATOR_H__