gcc4mbed/external/mbed/.svn/text-base/SPIHalfDuplex.h.svn-base

   1 /* mbed Microcontroller Library - SPI
   2  * Copyright (c) 2010 ARM Limited. All rights reserved.
   3  * jward
   4  */
   5
   6 #ifndef MBED_SPIHALFDUPLEX_H
   7 #define MBED_SPIHALFDUPLEX_H
   8
   9 #include "SPI.h"
  10
  11 namespace mbed {
  12
  13 /* Class: SPIHalfDuplex
  14  *   A SPI half-duplex master, used for communicating with SPI slave devices
  15  * over a shared data line.
  16  *
  17  * The default format is set to 8-bits for both master and slave, and a
  18  * clock frequency of 1MHz
  19  *
  20  * Most SPI devies will also require Chip Select and Reset signals. These
  21  * can be controlled using <DigitalOut> pins.
  22  *
  23  * Although this is for a shared data line, both MISO and MOSI are defined,
  24  * and should be tied together externally to the mbed. This class handles
  25  * the tri-stating of the MOSI pin.
  26  *
  27  * Example:
  28  * > // Send a byte to a SPI half-duplex slave, and record the response
  29  * >
  30  * > #include "mbed.h"
  31  * >
  32  * > SPIHalfDuplex device(p5, p6, p7) // mosi, miso, sclk
  33  * >
  34  * > int main() {
  35  * >     int respone = device.write(0xAA);
  36  * > }
  37  */
  38
  39 class SPIHalfDuplex : public SPI {
  40
  41 public:
  42
  43     /* Constructor: SPIHalfDuplex
  44      *  Create a SPI half-duplex master connected to the specified pins
  45      *
  46      * Variables:
  47      *  mosi - SPI Master Out, Slave In pin
  48      *  miso - SPI Master In, Slave Out pin
  49      *  sclk - SPI Clock pin
  50      *  name - (optional) A string to identify the object
  51      *
  52      * Pin Options:
  53      *  (5, 6, 7) or (11, 12, 13)
  54      *
  55      *  mosi or miso can be specfied as NC if not used
  56      */
  57     SPIHalfDuplex(PinName mosi, PinName miso, PinName sclk,
  58         const char *name = NULL);
  59
  60 #if 0 // Inherited from SPI - documentation only
  61     /* Function: format
  62      *  Configure the data transmission format
  63      *
  64      * Variables:
  65      *  bits - Number of bits per SPI frame (4 - 16)
  66      *  mode - Clock polarity and phase mode (0 - 3)
  67      *
  68      * > mode | POL PHA
  69      * > -----+--------
  70      * >   0  |  0   0
  71      * >   1  |  0   1
  72      * >   2  |  1   0
  73      * >   3  |  1   1
  74      */
  75     void format(int bits, int mode = 0);
  76
  77     /* Function: frequency
  78      *  Set the spi bus clock frequency
  79      *
  80      * Variables:
  81      *  hz - SCLK frequency in hz (default = 1MHz)
  82      */
  83     void frequency(int hz = 1000000);
  84 #endif
  85
  86     /* Function: write
  87      *  Write to the SPI Slave and return the response
  88      *
  89      * Variables:
  90      *  value - Data to be sent to the SPI slave
  91      *  returns - Response from the SPI slave
  92      */
  93     virtual int write(int value);
  94
  95     /* Function: slave_format
  96      *  Set the number of databits expected from the slave, from 4-16
  97      *
  98      * Variables:
  99      *  sbits - Number of expected bits in the slave response
 100      */
 101     void slave_format(int sbits);
 102
 103 protected:
 104
 105     PinName _mosi;
 106     PinName _miso;
 107     int     _sbits;
 108
 109 }; // End of class
 110
 111 } // End of namespace mbed
 112
 113 #endif