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SerialHalfDuplex Class Reference
Public Member Functions | Protected Member Functions

SerialHalfDuplex Class Reference

A serial port (UART) for communication with other devices using Half-Duplex, allowing transmit and receive on a single shared transmit and receive line. More...

#include <SerialHalfDuplex.h>

Inherits mbed::Serial.

Public Member Functions

 SerialHalfDuplex (PinName tx, PinName rx)
 Create a half-duplex serial port, connected to the specified transmit and receive pins.
void baud (int baudrate)
 Set the baud rate of the serial port.
void format (int bits=8, Parity parity=SerialBase::None, int stop_bits=1)
 Set the transmission format used by the serial port.
int readable ()
 Determine if there is a character available to read.
int writeable ()
 Determine if there is space available to write a character.
void attach (Callback< void()> func, IrqType type=RxIrq)
 Attach a function to call whenever a serial interrupt is generated.
template<typename T >
 MBED_DEPRECATED_SINCE ("mbed-os-5.1","The attach function does not support cv-qualifiers. Replaced by ""attach(callback(obj, method), type).") void attach(T *obj
 Attach a member function to call whenever a serial interrupt is generated.
void set_flow_control (Flow type, PinName flow1=NC, PinName flow2=NC)
 Set the flow control type on the serial port.
int write (const uint8_t *buffer, int length, const event_callback_t &callback, int event=SERIAL_EVENT_TX_COMPLETE)
 Begin asynchronous write using 8bit buffer.
int write (const uint16_t *buffer, int length, const event_callback_t &callback, int event=SERIAL_EVENT_TX_COMPLETE)
 Begin asynchronous write using 16bit buffer.
void abort_write ()
 Abort the on-going write transfer.
int read (uint8_t *buffer, int length, const event_callback_t &callback, int event=SERIAL_EVENT_RX_COMPLETE, unsigned char char_match=SERIAL_RESERVED_CHAR_MATCH)
 Begin asynchronous reading using 8bit buffer.
int read (uint16_t *buffer, int length, const event_callback_t &callback, int event=SERIAL_EVENT_RX_COMPLETE, unsigned char char_match=SERIAL_RESERVED_CHAR_MATCH)
 Begin asynchronous reading using 16bit buffer.
void abort_read ()
 Abort the on-going read transfer.
int set_dma_usage_tx (DMAUsage usage)
 Configure DMA usage suggestion for non-blocking TX transfers.
int set_dma_usage_rx (DMAUsage usage)
 Configure DMA usage suggestion for non-blocking RX transfers.

Protected Member Functions

virtual void lock ()
 Acquire exclusive access to this serial port.
virtual void unlock ()
 Release exclusive access to this serial port.
virtual ssize_t write (const void *buffer, size_t length)
 Write the contents of a buffer to the file.
virtual ssize_t read (void *buffer, size_t length)
 Function read Reads the contents of the file into a buffer.
virtual int close ()
 Close the file.
virtual off_t lseek (off_t offset, int whence)
 Move the file position to a given offset from a given location.
virtual int isatty ()
 Check if the handle is for a interactive terminal device.
virtual int fsync ()
 Flush any buffers associated with the FileHandle, ensuring it is up to date on disk.

Detailed Description

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.

For Simplex and Full-Duplex Serial communication, see Serial()

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());
         }
     }
 }

Definition at line 57 of file SerialHalfDuplex.h.

Constructor & Destructor Documentation

SerialHalfDuplex ( PinName  tx,
PinName  rx 
)

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

Parameters:
txTransmit pin
rxReceive pin

Definition at line 14 of file SerialHalfDuplex.cpp.

Member Function Documentation

void baud ( int  baudrate ) [inherited]

Set the baud rate of the serial port.

Parameters:
baudrateThe baudrate of the serial port (default = 9600).

Definition at line 43 of file SerialBase.cpp.

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