SPIHalfDuplex.h

00001 /* mbed Microcontroller Library - SPIHalfDuplex
00002  * Copyright (c) 2010-2011 ARM Limited. All rights reserved.
00003  */
00004 #ifndef MBED_SPIHALFDUPLEX_H
00005 #define MBED_SPIHALFDUPLEX_H
00006 
00007 #include "platform.h"
00008 
00009 #if DEVICE_SPI
00010 
00011 #include "SPI.h"
00012 
00013 namespace mbed {
00014 
00015 /** A SPI half-duplex master, used for communicating with SPI slave devices
00016  * over a shared data line.
00017  *
00018  * The default format is set to 8-bits for both master and slave, and a
00019  * clock frequency of 1MHz
00020  *
00021  * Most SPI devies will also require Chip Select and Reset signals. These
00022  * can be controlled using <DigitalOut> pins.
00023  *
00024  * Although this is for a shared data line, both MISO and MOSI are defined,
00025  * and should be tied together externally to the mbed. This class handles
00026  * the tri-stating of the MOSI pin.
00027  *
00028  * Example:
00029  * @code
00030  * // Send a byte to a SPI half-duplex slave, and record the response
00031  *
00032  * #include "mbed.h"
00033  *
00034  * SPIHalfDuplex device(p5, p6, p7) // mosi, miso, sclk
00035  *
00036  * int main() {
00037  *     int respone = device.write(0xAA);
00038  * }
00039  * @endcode
00040  */
00041 
00042 class SPIHalfDuplex : public SPI {
00043 
00044 public:
00045 
00046     /** Create a SPI half-duplex master connected to the specified pins
00047      *
00048      * Pin Options:
00049      *  (5, 6, 7) or (11, 12, 13)
00050      *
00051      *  mosi or miso can be specfied as NC if not used
00052      *
00053      *  @param mosi SPI Master Out, Slave In pin
00054      *  @param miso SPI Master In, Slave Out pin
00055      *  @param sclk SPI Clock pin
00056      *  @param name (optional) A string to identify the object
00057      */
00058     SPIHalfDuplex(PinName mosi, PinName miso, PinName sclk);
00059 
00060     /** Write to the SPI Slave and return the response
00061      *
00062      *  @param value Data to be sent to the SPI slave
00063      *
00064      *  @returns
00065      *    Response from the SPI slave
00066      */
00067     virtual int write(int value);
00068 
00069     /** Set the number of databits expected from the slave, from 4-16
00070      *
00071      *  @param sbits Number of expected bits in the slave response
00072      */
00073     void slave_format(int sbits);
00074 
00075 protected:
00076     PinName _mosi;
00077     PinName _miso;
00078     int     _sbits;
00079 }; // End of class
00080 
00081 } // End of namespace mbed
00082 
00083 #endif
00084 
00085 #endif