MTSSerialFlowControl.h

00001 #ifndef MTSSERIALFLOWCONTROL_H
00002 #define MTSSERIALFLOWCONTROL_H
00003 
00004 #include "MTSSerial.h"
00005 
00006 namespace mts
00007 {
00008 
00009 /** This class derives from MTSBufferedIO/MTSSerial and provides a buffered wrapper to the
00010 * standard mbed Serial class along with generic RTS/CTS HW flow control. Since it
00011 * depends only on the mbed Serial, DigitalOut and DigitalIn classes for accessing
00012 * the serial data, this class is inherently portable accross different mbed platforms
00013 * and provides HW flow control even when not natively supported by the processors
00014 * serial port. If HW flow control is not needed, use MTSSerial instead. It should also
00015 * be noted that the RTS/CTS functionality in this class is implemented as a DTE device.
00016 */
00017 class MTSSerialFlowControl : public MTSSerial
00018 {
00019 public:
00020     /** Creates a new MTSSerialFlowControl object that can be used to talk to an mbed serial
00021     * port through internal SW buffers. Note that this class also adds the ability to use
00022     * RTS/CTS HW Flow Conrtol through and standard mbed DigitalIn and DigitalOut pins.
00023     * The RTS and CTS functionality assumes this is a DTE device.
00024     *
00025     * @param TXD the transmit data pin on the desired mbed serial interface.
00026     * @param RXD the receive data pin on the desired mbed serial interface.
00027     * @param RTS the DigitalOut pin that RTS will be attached to. (DTE)
00028     * @param CTS the DigitalIn pin that CTS will be attached to. (DTE)
00029     * @param txBufferSize the size in bytes of the internal SW transmit buffer. The
00030     * default is 256 bytes.
00031     * @param rxBufferSize the size in bytes of the internal SW receive buffer. The
00032     * default is 256 bytes.
00033     */
00034     MTSSerialFlowControl(PinName TXD, PinName RXD, PinName RTS, PinName CTS, int txBufSize = 256, int rxBufSize = 256);
00035 
00036     /** Destructs an MTSSerialFlowControl object and frees all related resources.
00037     */
00038     ~MTSSerialFlowControl();
00039     
00040     //Overriden from MTSBufferedIO to support flow control correctly
00041     virtual void rxClear();
00042 
00043 private:
00044     void notifyStartSending(); // Used to set cts start signal
00045     void notifyStopSending(); // Used to set cts stop signal
00046     
00047     //This device acts as a DTE
00048     bool rxReadyFlag;   //Tracks state change for rts signaling
00049     DigitalOut rts; // Used to tell DCE to send or not send data
00050     DigitalIn cts; // Used to check if DCE is ready for data
00051     int highThreshold; // High water mark for setting cts to stop
00052     int lowThreshold; // Low water mark for setting cts to start
00053 
00054     virtual void handleRead(); // Method for handling data to be read
00055     virtual void handleWrite(); // Method for handling data to be written
00056 };
00057 
00058 }
00059 
00060 #endif /* MTSSERIALFLOWCONTROL */