DMAFuncGen.h

00001 #ifndef MBED_DMAFUNCGEN_H
00002 #define MBED_DMAFUNCGEN_H
00003 
00004 #include "mbed.h"
00005 #include "MODDMA.h"
00006 
00007 //! DMAFuncGen class generates a waveform on Analog output using Direct Memory Access alone.
00008 class DMAFuncGen {
00009 public:
00010     /// Create DMAFucGen instance
00011     /// @param dma The dma to use.
00012     /// @param channel The dma channel to use for transferring data to the D/A converter.
00013     DMAFuncGen(MODDMA& dma, MODDMA::CHANNELS channel);
00014 
00015     /// Number of data points in the waveform. Must be set by client.
00016     int buffer_size;
00017     /// Buffer for the binary data that will be transferred by DMA. Must be allocated by client.
00018     uint32_t* buffer;
00019 
00020     /// Set waveform value for a specified data point.
00021     /// @param idx The index of the data point in #buffer, must be in range 0..#buffer_size-1.
00022     /// @param x The value for the D/A, in the range 0..65535.
00023     void set(int idx, uint16_t x);
00024     /// Get waveform value for a specified data point
00025     /// @param idx The index of the data point in the #buffer, in the range 0..#buffer_size-1.
00026     /// @returns The value for the data point, in the range 0..65535.
00027     uint16_t operator[](const uint16_t idx);
00028     
00029     /// Connect the D/A converter pin (enable output)
00030     void Connect();
00031     /// Disconnect the D/A converter pin (pin becomes tri-state)
00032     void Disconnect();
00033 
00034     /// Reference to the DMA instance   
00035     MODDMA& dma;
00036     
00037     /// Set up the dma.
00038     /// Must set #buffer and #buffer_size first.
00039     void Setup(void);
00040     
00041     /// Set waveform frequency
00042     /// @note Must set #buffer_size first.
00043     /// @param f Frequency of a complete cycle of the waveform (in Hz). 
00044     void SetFrequency(float f);
00045     /// Read the actual waveform frequency that will be generated.
00046     float Frequency();
00047     
00048     /// Start generating the waveform (start dma)
00049     void Start();
00050     /// Stop generating the waveform (but waits for the current cycle to complete)
00051     void Stop();
00052 
00053 private:
00054     MODDMA_Config conf;
00055     MODDMA_LLI lli;
00056 
00057     /// ISR routine, called on Terminal Count
00058     void TC_callback(void);
00059     /// ISR routine, called on dma ERRor
00060     void ERR_callback(void);
00061 };
00062 
00063 #endif