SPISlave.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #ifndef MBED_SPISLAVE_H
00017 #define MBED_SPISLAVE_H
00018 
00019 #include "platform/platform.h"
00020 #include "platform/NonCopyable.h"
00021 
00022 #if defined (DEVICE_SPISLAVE) || defined(DOXYGEN_ONLY)
00023 
00024 #include "hal/spi_api.h"
00025 
00026 namespace mbed {
00027 /** \addtogroup drivers */
00028 
00029 /** A SPI slave, used for communicating with a SPI master device.
00030  *
00031  * The default format is set to 8 bits, mode 0 and a clock frequency of 1MHz.
00032  *
00033  * @note Synchronization level: Not protected
00034  *
00035  * Example of how to reply to a SPI master as slave:
00036  * @code
00037  *
00038  * #include "mbed.h"
00039  *
00040  * SPISlave device(SPI_MOSI, SPI_MISO, SPI_SCLK, SPI_CS);
00041  *
00042  * int main() {
00043  *     device.reply(0x00);              // Prime SPI with first reply
00044  *     while(1) {
00045  *         if(device.receive()) {
00046  *             int v = device.read();   // Read byte from master
00047  *             v = (v + 1) % 0x100;     // Add one to it, modulo 256
00048  *             device.reply(v);         // Make this the next reply
00049  *         }
00050  *     }
00051  * }
00052  * @endcode
00053  * @ingroup drivers
00054  */
00055 class SPISlave : private NonCopyable<SPISlave> {
00056 
00057 public:
00058 
00059     /** Create a SPI slave connected to the specified pins.
00060      *
00061      *  @note Either mosi or miso can be specified as NC if not used.
00062      *
00063      *  @param mosi SPI Master Out, Slave In pin.
00064      *  @param miso SPI Master In, Slave Out pin.
00065      *  @param sclk SPI Clock pin.
00066      *  @param ssel SPI Chip Select pin.
00067      */
00068     SPISlave(PinName mosi, PinName miso, PinName sclk, PinName ssel);
00069 
00070     /** Configure the data transmission format.
00071      *
00072      *  @param bits Number of bits per SPI frame (4 - 16).
00073      *  @param mode Clock polarity and phase mode (0 - 3).
00074      *
00075      * @code
00076      * mode | POL PHA
00077      * -----+--------
00078      *   0  |  0   0
00079      *   1  |  0   1
00080      *   2  |  1   0
00081      *   3  |  1   1
00082      * @endcode
00083      */
00084     void format(int bits, int mode = 0);
00085 
00086     /** Set the SPI bus clock frequency.
00087      *
00088      *  @param hz Clock frequency in hz (default = 1MHz).
00089      */
00090     void frequency(int hz = 1000000);
00091 
00092     /** Polls the SPI to see if data has been received.
00093      *
00094      *  @return Presence of received data.
00095      *  @retval 0 No data waiting.
00096      *  @retval 1 Data waiting.
00097      */
00098     int receive(void);
00099 
00100     /** Retrieve data from receive buffer as slave.
00101      *
00102      *  @return The data in the receive buffer.
00103      */
00104     int read(void);
00105 
00106     /** Fill the transmission buffer with the value to be written out
00107      *  as slave on the next received message from the master.
00108      *
00109      *  @param value The data to be transmitted next.
00110      */
00111     void reply(int value);
00112 
00113 #if !defined(DOXYGEN_ONLY)
00114 
00115 protected:
00116     /* Internal SPI object identifying the resources */
00117     spi_t _spi;
00118 
00119     /* How many bits in an SPI frame */
00120     int _bits;
00121     /* Clock phase and polarity */
00122     int _mode;
00123     /* Clock frequency */
00124     int _hz;
00125 
00126 #endif //!defined(DOXYGEN_ONLY)
00127 };
00128 
00129 } // namespace mbed
00130 
00131 #endif
00132 
00133 #endif