MTSSerialFlowControl.h

00001 /* Universal Socket Modem Interface Library
00002 * Copyright (c) 2013 Multi-Tech Systems
00003 *
00004 * Licensed under the Apache License, Version 2.0 (the "License");
00005 * you may not use this file except in compliance with the License.
00006 * You may obtain a copy of the License at
00007 *
00008 *     http://www.apache.org/licenses/LICENSE-2.0
00009 *
00010 * Unless required by applicable law or agreed to in writing, software
00011 * distributed under the License is distributed on an "AS IS" BASIS,
00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013 * See the License for the specific language governing permissions and
00014 * limitations under the License.
00015 */
00016 
00017 #ifndef MTSSERIALFLOWCONTROL_H
00018 #define MTSSERIALFLOWCONTROL_H
00019 
00020 #include "mbed.h"
00021 #include "MTSSerial.h"
00022 
00023 
00024 namespace mts
00025 {
00026 
00027 /** This class derives from MTSBufferedIO/MTSSerial and provides a buffered wrapper to the
00028 * standard mbed Serial class along with generic RTS/CTS HW flow control. Since it
00029 * depends only on the mbed Serial, DigitalOut and InterruptIn classes for accessing
00030 * the serial data, this class is inherently portable accross different mbed platforms
00031 * and provides HW flow control even when not natively supported by the processors
00032 * serial port. If HW flow control is not needed, use MTSSerial instead. It should also
00033 * be noted that the RTS/CTS functionality in this class is implemented as a DTE device.
00034 */
00035 class MTSSerialFlowControl : public MTSSerial
00036 {
00037 public:
00038     /** Creates a new MTSSerialFlowControl object that can be used to talk to an mbed serial
00039     * port through internal SW buffers. Note that this class also adds the ability to use
00040     * RTS/CTS HW Flow Conrtol through and standard mbed DigitalIn and DigitalOut pins.
00041     * The RTS and CTS functionality assumes this is a DTE device.
00042     *
00043     * @param TXD the transmit data pin on the desired mbed serial interface.
00044     * @param RXD the receive data pin on the desired mbed serial interface.
00045     * @param RTS the DigitalOut pin that RTS will be attached to. (DTE)
00046     * @param CTS the DigitalIn pin that CTS will be attached to. (DTE)
00047     * @param txBufferSize the size in bytes of the internal SW transmit buffer. The
00048     * default is 64 bytes.
00049     * @param rxBufferSize the size in bytes of the internal SW receive buffer. The
00050     * default is 64 bytes.
00051     * @param name an optional name for the serial port. The default is blank.
00052     */
00053     MTSSerialFlowControl(PinName TXD, PinName RXD, PinName RTS, PinName CTS, int txBufSize = 64, int rxBufSize = 64);
00054 
00055     /** Destructs an MTSSerialFlowControl object and frees all related resources,
00056     * including internal buffers.
00057     */
00058     ~MTSSerialFlowControl();
00059     
00060     /** This method clears all the data from the internal Rx or read buffer.
00061     */
00062     virtual void rxClear();
00063 
00064 private:
00065     void notifyStartSending(); // Used to set cts start signal
00066     void notifyStopSending(); // Used to set cts stop signal
00067     
00068     //This device acts as a DTE
00069     bool rxReadyFlag;   //Tracks state change for rts signaling
00070     DigitalOut rts; // Used to tell DCE to send or not send data
00071     DigitalIn cts; // Used to check if DCE is ready for data
00072     int highThreshold; // High water mark for setting cts to stop
00073     int lowThreshold; // Low water mark for setting cts to start
00074 
00075     virtual void handleRead(); // Method for handling data to be read
00076     virtual void handleWrite(); // Method for handling data to be written
00077 };
00078 
00079 }
00080 
00081 #endif /* MTSSERIALFLOWCONTROL */