Revision 0:7802a25daf3b, committed 2012-12-06

Comitter:

mbed_unsupported

Date:

Thu Dec 06 12:46:52 2012 +0000

Child:

1:8fd1fa67565e

Commit message:

Serial Half-Duplex

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SerialHalfDuplex.cpp	Thu Dec 06 12:46:52 2012 +0000
@@ -0,0 +1,76 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2012 ARM Limited
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * NOTE: This is an unsupported legacy untested library.
+ */
+#include "SerialHalfDuplex.h"
+
+#if DEVICE_SERIAL
+
+#include "pinmap.h"
+#include "serial_api.h"
+#include "gpio_api.h"
+
+namespace mbed {
+
+SerialHalfDuplex::SerialHalfDuplex(PinName tx, PinName rx, const char *name)
+    : Serial(tx, rx, name) {
+    _txpin = tx;
+    
+    gpio_input(_txpin);         // set as input 
+    pin_mode(_txpin, PullNone); // no pull
+    pin_function(_txpin, 0);    // set as gpio
+}
+
+// To transmit a byte in half duplex mode:
+// 1. Disable interrupts, so we don't trigger on loopback byte
+// 2. Set tx pin to UART out
+// 3. Transmit byte as normal
+// 4. Read back byte from looped back tx pin - this both confirms that the
+//    transmit has occurred, and also clears the byte from the buffer.
+// 5. Return pin to input mode
+// 6. Re-enable interrupts
+
+int SerialHalfDuplex::_putc(int c) {
+    int retc;
+    
+    // TODO: We should not disable all interrupts
+    __disable_irq();
+    
+    serial_pinout_tx(_txpin);
+    
+    Serial::_putc(c);
+    retc = Serial::getc();       // reading also clears any interrupt
+    
+    pin_function(_txpin, 0);
+    
+    __enable_irq();
+    
+    return retc;
+}
+
+int SerialHalfDuplex::_getc(void) {
+    return Serial::_getc();
+}
+
+} // End namespace
+
+#endif

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SerialHalfDuplex.h	Thu Dec 06 12:46:52 2012 +0000
@@ -0,0 +1,207 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2012 ARM Limited
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * NOTE: This is an unsupported legacy untested library.
+ */
+#ifndef MBED_SERIALHALFDUPLEX_H
+#define MBED_SERIALHALFDUPLEX_H
+
+#include "device.h"
+
+#if DEVICE_SERIAL
+
+#include "Serial.h"
+#include "PinNames.h"
+#include "PeripheralNames.h"
+
+namespace mbed {
+
+/* Class: SerialHalfDuplex
+ * A serial port (UART) for communication with other devices using  
+ * Half-Duplex, allowing transmit and receive on a single
+ * shared transmit and receive line. Only one end should be transmitting 
+ * at a time.
+ * 
+ * Both the tx and rx pin should be defined, and wired together. 
+ * This is in addition to them being wired to the other serial 
+ * device to allow both read and write functions to operate.
+ *
+ *  Example:
+ *  > // Send a byte to a second HalfDuplex device, and read the response
+ *  >
+ *  > #include "mbed.h"
+ *  >
+ *  > // p9 and p10 should be wired together to form "a"
+ *  > // p28 and p27 should be wired together to form "b"
+ *  > // p9/p10 should be wired to p28/p27 as the Half Duplex connection
+ *  >
+ *  > SerialHalfDuplex a(p9, p10);
+ *  > SerialHalfDuplex b(p28, p27);
+ *  >
+ *  > void b_rx() { // second device response
+ *  >     b.putc(b.getc() + 4);
+ *  > }
+ *  >   
+ *  > int main() {
+ *  >     b.attach(&b_rx);
+ *  >     for(int c = 'A'; c < 'Z'; c++) {
+ *  >         a.putc(c);
+ *  >         printf("sent [%c]\n", c);
+ *  >         wait(0.5);   // b should respond
+ *  >         if(a.readable()) {
+ *  >             printf("received [%c]\n", a.getc());
+ *  >         }
+ *  >     }
+ *  > }
+ * 
+ * For Simplex and Full-Duplex Serial communication, see <Serial>
+ */
+class SerialHalfDuplex : public Serial {
+
+public:
+    /* Constructor: SerialHalfDuplex
+     * Create a half-duplex serial port, connected to the specified transmit
+     * and receive pins.
+     *
+     * These pins should be wired together, as well as to the target device
+     *
+     * Variables:
+     *  tx - Transmit pin
+     *  rx - Receive pin
+     */
+    SerialHalfDuplex(PinName tx, PinName rx, const char *name = NULL);
+
+#if 0       // Inherited from Serial class, for documentation
+    /* Function: baud
+     *  Set the baud rate of the serial port
+     *
+     * Variables:
+     *  baudrate - The baudrate of the serial port (default = 9600).
+     */
+    void baud(int baudrate);
+
+    enum Parity {
+        None = 0
+        , Odd
+        , Even
+        , Forced1
+        , Forced0
+    };
+
+    /* Function: format
+     *  Set the transmission format used by the Serial port
+     *
+     * Variables:
+     *  bits - The number of bits in a word (5-8; default = 8)
+     *  parity - The parity used (Serial::None, Serial::Odd, 
+Serial::Even, Serial::Forced1, Serial::Forced0; default = Serial::None)
+     *  stop - The number of stop bits (1 or 2; default = 1)
+     */
+    void format(int bits = 8, Parity parity = Serial::None, int stop_bits 
+= 1);
+
+    /* Function: putc
+     *  Write a character
+     *
+     * Variables:
+     *  c - The character to write to the serial port
+     */
+    int putc(int c);
+
+    /* Function: getc
+     *  Read a character
+     *
+     * Read a character from the serial port. This call will block
+     * until a character is available. For testing if a character is
+     * available for reading, see <readable>.
+     *
+     * Variables:
+     *  returns - The character read from the serial port
+     */
+    int getc();
+
+    /* Function: printf
+     *  Write a formated string
+     *
+     * Variables:
+     *  format - A printf-style format string, followed by the
+     *      variables to use in formating the string.
+     */
+    int printf(const char* format, ...);
+
+    /* Function: scanf
+     *  Read a formated string
+     *
+     * Variables:
+     *  format - A scanf-style format string,
+     *      followed by the pointers to variables to store the results.
+     */
+    int scanf(const char* format, ...);
+
+    /* Function: readable
+     *  Determine if there is a character available to read
+     *
+     * Variables:
+     *  returns - 1 if there is a character available to read, else 0
+     */
+    int readable();
+
+    /* Function: writeable
+     *  Determine if there is space available to write a character
+     *
+     * Variables:
+     *  returns - 1 if there is space to write a character, else 0
+     */
+    int writeable();
+
+    /* Function: attach
+     *  Attach a function to call whenever a serial interrupt is generated
+     *
+     * Variables:
+     *  fptr - A pointer to a void function, or 0 to set as none
+     */
+    void attach(void (*fptr)(void));
+
+    /* Function: attach
+     *  Attach a member function to call whenever a serial interrupt is generated
+     *
+     * Variables:
+     *  tptr - pointer to the object to call the member function on
+     *  mptr - pointer to the member function to be called
+     */
+    template<typename T>
+    void attach(T* tptr, void (T::*mptr)(void));
+
+#endif
+
+protected:
+    PinName     _txpin;
+
+    virtual int _putc(int c);
+    virtual int _getc(void);
+
+}; // End class SerialHalfDuplex
+
+} // End namespace
+
+#endif
+
+#endif