SPISlave.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  * SPDX-License-Identifier: Apache-2.0
00004  *
00005  * Licensed under the Apache License, Version 2.0 (the "License");
00006  * you may not use this file except in compliance with the License.
00007  * You may obtain a copy of the License at
00008  *
00009  *     http://www.apache.org/licenses/LICENSE-2.0
00010  *
00011  * Unless required by applicable law or agreed to in writing, software
00012  * distributed under the License is distributed on an "AS IS" BASIS,
00013  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00014  * See the License for the specific language governing permissions and
00015  * limitations under the License.
00016  */
00017 #ifndef MBED_SPISLAVE_H
00018 #define MBED_SPISLAVE_H
00019 
00020 #include "platform/platform.h"
00021 #include "platform/NonCopyable.h"
00022 
00023 #if DEVICE_SPISLAVE || defined(DOXYGEN_ONLY)
00024 
00025 #include "hal/spi_api.h"
00026 
00027 namespace mbed {
00028 /** \addtogroup drivers */
00029 
00030 /** A SPI slave, used for communicating with a SPI master device.
00031  *
00032  * The default format is set to 8 bits, mode 0 and a clock frequency of 1MHz.
00033  *
00034  * @note Synchronization level: Not protected
00035  *
00036  * Example of how to reply to a SPI master as slave:
00037  * @code
00038  *
00039  * #include "mbed.h"
00040  *
00041  * SPISlave device(SPI_MOSI, SPI_MISO, SPI_SCLK, SPI_CS);
00042  *
00043  * int main() {
00044  *     device.reply(0x00);              // Prime SPI with first reply
00045  *     while(1) {
00046  *         if(device.receive()) {
00047  *             int v = device.read();   // Read byte from master
00048  *             v = (v + 1) % 0x100;     // Add one to it, modulo 256
00049  *             device.reply(v);         // Make this the next reply
00050  *         }
00051  *     }
00052  * }
00053  * @endcode
00054  * @ingroup drivers
00055  */
00056 class SPISlave : private NonCopyable<SPISlave> {
00057 
00058 public:
00059 
00060     /** Create a SPI slave connected to the specified pins.
00061      *
00062      *  @note Either mosi or miso can be specified as NC if not used.
00063      *
00064      *  @param mosi SPI Master Out, Slave In pin.
00065      *  @param miso SPI Master In, Slave Out pin.
00066      *  @param sclk SPI Clock pin.
00067      *  @param ssel SPI Chip Select pin.
00068      */
00069     SPISlave(PinName mosi, PinName miso, PinName sclk, PinName ssel);
00070 
00071     /** Configure the data transmission format.
00072      *
00073      *  @param bits Number of bits per SPI frame (4 - 16).
00074      *  @param mode Clock polarity and phase mode (0 - 3).
00075      *
00076      * @code
00077      * mode | POL PHA
00078      * -----+--------
00079      *   0  |  0   0
00080      *   1  |  0   1
00081      *   2  |  1   0
00082      *   3  |  1   1
00083      * @endcode
00084      */
00085     void format(int bits, int mode = 0);
00086 
00087     /** Set the SPI bus clock frequency.
00088      *
00089      *  @param hz Clock frequency in hz (default = 1MHz).
00090      */
00091     void frequency(int hz = 1000000);
00092 
00093     /** Polls the SPI to see if data has been received.
00094      *
00095      *  @return Presence of received data.
00096      *  @retval 0 No data waiting.
00097      *  @retval 1 Data waiting.
00098      */
00099     int receive(void);
00100 
00101     /** Retrieve data from receive buffer as slave.
00102      *
00103      *  @return The data in the receive buffer.
00104      */
00105     int read(void);
00106 
00107     /** Fill the transmission buffer with the value to be written out
00108      *  as slave on the next received message from the master.
00109      *
00110      *  @param value The data to be transmitted next.
00111      */
00112     void reply(int value);
00113 
00114 #if !defined(DOXYGEN_ONLY)
00115 
00116 protected:
00117     /* Internal SPI object identifying the resources */
00118     spi_t _spi;
00119 
00120     /* How many bits in an SPI frame */
00121     int _bits;
00122     /* Clock phase and polarity */
00123     int _mode;
00124     /* Clock frequency */
00125     int _hz;
00126 
00127 #endif //!defined(DOXYGEN_ONLY)
00128 };
00129 
00130 } // namespace mbed
00131 
00132 #endif
00133 
00134 #endif