SerialHalfDuplex.h

00001 /* mbed Microcontroller Library - SerialHalfDuplex
00002  * Copyright (c) 2010-2011 ARM Limited. All rights reserved.
00003  */
00004 
00005 #ifndef MBED_SERIALHALFDUPLEX_H
00006 #define MBED_SERIALHALFDUPLEX_H
00007 
00008 #include "device.h"
00009 
00010 #if DEVICE_SERIAL
00011 
00012 #include "Serial.h"
00013 #include "PinNames.h"
00014 #include "PeripheralNames.h"
00015 
00016 namespace mbed {
00017 
00018 /** A serial port (UART) for communication with other devices using  
00019  *  Half-Duplex, allowing transmit and receive on a single
00020  *  shared transmit and receive line. Only one end should be transmitting 
00021  *  at a time.
00022  * 
00023  *  Both the tx and rx pin should be defined, and wired together. 
00024  *  This is in addition to them being wired to the other serial 
00025  *  device to allow both read and write functions to operate.
00026  *
00027  *  For Simplex and Full-Duplex Serial communication, see Serial()
00028  *
00029  * Example:
00030  * @code
00031  * // Send a byte to a second HalfDuplex device, and read the response
00032  * 
00033  * #include "mbed.h"
00034  *
00035  * // p9 and p10 should be wired together to form "a"
00036  * // p28 and p27 should be wired together to form "b"
00037  * // p9/p10 should be wired to p28/p27 as the Half Duplex connection
00038  *
00039  * SerialHalfDuplex a(p9, p10);
00040  * SerialHalfDuplex b(p28, p27);
00041  *
00042  * void b_rx() { // second device response
00043  *     b.putc(b.getc() + 4);
00044  * }
00045  *   
00046  * int main() {
00047  *     b.attach(&b_rx);
00048  *     for (int c = 'A'; c < 'Z'; c++) {
00049  *         a.putc(c);
00050  *         printf("sent [%c]\n", c);
00051  *         wait(0.5);   // b should respond
00052  *         if (a.readable()) {
00053  *             printf("received [%c]\n", a.getc());
00054  *         }
00055  *     }
00056  * }
00057  * @endcode
00058  */
00059 class SerialHalfDuplex : public Serial {
00060 
00061 public:
00062     /** Create a half-duplex serial port, connected to the specified transmit
00063      *  and receive pins.
00064      *
00065      *  These pins should be wired together, as well as to the target device
00066      *
00067      *  @param tx Transmit pin
00068      *  @param rx Receive pin
00069      */
00070     SerialHalfDuplex(PinName tx, PinName rx, const char *name = NULL);
00071 
00072 #if 0       // Inherited from Serial class, for documentation
00073     /** Set the baud rate of the serial port
00074      *
00075      *  @param baudrate The baudrate of the serial port (default = 9600).
00076      */
00077     void baud(int baudrate);
00078 
00079     enum Parity {
00080         None = 0
00081         , Odd
00082         , Even
00083         , Forced1
00084         , Forced0
00085     };
00086 
00087     /** Set the transmission format used by the Serial port
00088      *
00089      *  @param bits The number of bits in a word (5-8; default = 8)
00090      *  @param parity The parity used (Serial::None, Serial::Odd, 
00091      *     Serial::Even, Serial::Forced1, Serial::Forced0; default = Serial::None)
00092      *  @param stop The number of stop bits (1 or 2; default = 1)
00093      */
00094     void format(int bits = 8, Parity parity = Serial::None, int stop_bits 
00095 = 1);
00096 
00097     /** Write a character
00098      *
00099      *  @param c The character to write to the serial port
00100      */
00101     int putc(int c);
00102 
00103     /** Read a character
00104      *
00105      *  Read a character from the serial port. This call will block
00106      *  until a character is available. For testing if a character is
00107      *  available for reading, see <readable>.
00108      *
00109      *  @returns
00110      *    The character read from the serial port
00111      */
00112     int getc();
00113 
00114     /** Write a formated string
00115      *
00116      *  @param format A printf-style format string, followed by the
00117      *    variables to use in formating the string.
00118      */
00119     int printf(const char* format, ...);
00120 
00121     /** Read a formated string
00122      *
00123      *  @param format A scanf-style format string,
00124      *    followed by the pointers to variables to store the results.
00125      */
00126     int scanf(const char* format, ...);
00127 
00128     /** Determine if there is a character available to read
00129      *
00130      *  @returns
00131      *    1 if there is a character available to read,
00132      *    0 otherwise
00133      */
00134     int readable();
00135 
00136     /** Determine if there is space available to write a character
00137      *
00138      *  @returns
00139      *    1 if there is space to write a character,
00140      *    0 otherwise
00141      */
00142     int writeable();
00143 
00144     /** Attach a function to call whenever a serial interrupt is generated
00145      *
00146      *  @param fptr A pointer to a void function, or 0 to set as none
00147      */
00148     void attach(void (*fptr)(void));
00149 
00150     /** Attach a member function to call whenever a serial interrupt is generated
00151      *
00152      *  @param tptr pointer to the object to call the member function on
00153      *  @param mptr pointer to the member function to be called
00154      */
00155     template<typename T>
00156     void attach(T* tptr, void (T::*mptr)(void));
00157 
00158 #endif
00159 
00160 protected:
00161     PinName     _txpin;
00162 
00163     virtual int _putc(int c);
00164     virtual int _getc(void);
00165 
00166 }; // End class SerialHalfDuplex
00167 
00168 } // End namespace
00169 
00170 #endif
00171 
00172 #endif