SPISlave.h

00001 /* mbed Microcontroller Library - SPISlave
00002  * Copyright (c) 2010-2011 ARM Limited. All rights reserved. 
00003  */
00004 
00005 #ifndef MBED_SPISLAVE_H
00006 #define MBED_SPISLAVE_H
00007 
00008 #include "device.h"
00009 
00010 #if DEVICE_SPISLAVE
00011 
00012 #include "platform.h"
00013 #include "PinNames.h"
00014 #include "PeripheralNames.h"
00015 #include "Base.h"
00016 
00017 namespace mbed {
00018 
00019 /** A SPI slave, used for communicating with a SPI Master device
00020  *
00021  *  The default format is set to 8-bits, mode 0, and a clock frequency of 1MHz
00022  *
00023  * Example:
00024  * @code
00025  * // Reply to a SPI master as slave
00026  *
00027  * #include "mbed.h"
00028  *
00029  * SPISlave device(p5, p6, p7, p8); // mosi, miso, sclk, ssel
00030  *
00031  * int main() {
00032  *     device.reply(0x00);              // Prime SPI with first reply
00033  *     while(1) {
00034  *         if(device.receive()) {
00035  *             int v = device.read();   // Read byte from master
00036  *             v = (v + 1) % 0x100;     // Add one to it, modulo 256
00037  *             device.reply(v);         // Make this the next reply
00038  *         }
00039  *     }
00040  * }
00041  * @endcode
00042  */ 
00043 class SPISlave : public Base {
00044 
00045 public:
00046 
00047     /** Create a SPI slave connected to the specified pins
00048      *
00049      *  Pin Options:
00050      *  (5, 6, 7i, 8) or (11, 12, 13, 14)
00051      *
00052      *  mosi or miso can be specfied as NC if not used
00053      *
00054      *  @param mosi SPI Master Out, Slave In pin
00055      *  @param miso SPI Master In, Slave Out pin
00056      *  @param sclk SPI Clock pin
00057      *  @param ssel SPI chip select pin
00058      *  @param name (optional) A string to identify the object     
00059      */
00060     SPISlave(PinName mosi, PinName miso, PinName sclk, PinName ssel,
00061         const char *name = NULL);
00062 
00063     /** Configure the data transmission format
00064      *
00065      *  @param bits Number of bits per SPI frame (4 - 16)
00066      *  @param mode Clock polarity and phase mode (0 - 3)
00067      *
00068      * @code
00069      * mode | POL PHA 
00070      * -----+--------     
00071      *   0  |  0   0 
00072      *   1  |  0   1
00073      *   2  |  1   0 
00074      *   3  |  1   1
00075      * @endcode
00076      */
00077     void format(int bits, int mode = 0);
00078 
00079     /** Set the spi bus clock frequency
00080      *
00081      *  @param hz SCLK frequency in hz (default = 1MHz)
00082      */
00083     void frequency(int hz = 1000000);
00084 
00085     /** Polls the SPI to see if data has been received
00086      *
00087      *  @returns
00088      *    0 if no data,
00089      *    1 otherwise
00090      */
00091     int receive(void);
00092 
00093     /** Retrieve  data from receive buffer as slave
00094      *
00095      *  @returns
00096      *    the data in the receive buffer
00097      */
00098     int read(void);
00099 
00100     /** Fill the transmission buffer with the value to be written out
00101      *  as slave on the next received message from the master.
00102      *
00103      *  @param value the data to be transmitted next
00104      */
00105     void reply(int value);
00106 
00107 protected:
00108 
00109     SPIName _spi;
00110     
00111     int _bits;
00112     int _mode;
00113     int _hz;
00114 
00115 };
00116 
00117 } // namespace mbed
00118 
00119 #endif
00120 
00121 #endif