InterruptPinCapture.h

00001 ///////////////////////////////////////////////////////////////////////////////
00002 // Signal Capture Library
00003 // Author: Chris Taylor (taylorza)
00004 #ifndef __INTERRUPTPINCAPTURE_H__
00005 #define __INTERRUPTPINCAPTURE_H__
00006 
00007 /** Captures the digital wave form of an interrupt capable pin into a timing buffer. */
00008 class InterruptPinCapture
00009 {
00010     public:
00011         /** Create an instance of InterruptPinCapture connected to the specified pin */
00012         InterruptPinCapture(PinName pin, PinMode mode);
00013         
00014         /** Maximum time to wait for waveform data to arrive or completely fill the timing buffer. 
00015          * @param us Timeout specified in microseconds
00016          */
00017         void setReadTimeout(uint32_t us);
00018         
00019         /** Waits for the pin to transition to the trigger state and proceeds to capture the
00020          * pins transition timing into the timing buffer.
00021          * @param triggerState State that the pin must transistion to before the readings are captured
00022          * @param pReadings Pointer to the timing buffer that will contain the readings in microseconds
00023          * @param count The maximum number of readings that can be held in the buffer
00024          * @returns The number of timings captured in the buffer.
00025          */      
00026         int read(bool triggerState, uint32_t *pReadings, int count);
00027         
00028         /** Immediately start capturing the pin transition timing into the timing buffer.
00029          * @param pInitialState Pointer to a bool that will have the initial state of the pin at the time the capture started.
00030          * @param pReadings Pointer to the timing buffer that will contain the readings in microseconds
00031          * @param count The maximum number of readings that can be held in the buffer
00032          * @returns The number of timings captured in the buffer.
00033          */      
00034         int read(bool *pInitialState, uint32_t *pReadings, int count);
00035         
00036     private:
00037         int readInternal(bool *pPinState, uint32_t *pReadings, int count, bool waitForTrigger);
00038         
00039     private:
00040         void onPinTransition();
00041         
00042         enum State
00043         {
00044             Stopped,
00045             WaitForTrigger,
00046             StartCapturing,
00047             Capturing
00048         };
00049         
00050     private:
00051         bool _started;
00052         uint32_t _readTimeout;        
00053         volatile State _state;        
00054         InterruptIn _signalPin;            
00055         
00056         uint32_t *_pBuffer;
00057         int _bufferMaxCount;
00058         int _bufferIndex;
00059         int _startPinState;
00060         
00061         int _triggerState;
00062         uint32_t _lastTransitionTime;
00063         Timer _timer;
00064 };
00065 #endif //__INTERRUPTPINCAPTURE_H__