SPI.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2015 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_SPI_H
00017 #define MBED_SPI_H
00018 
00019 #include "platform/platform.h"
00020 
00021 #if DEVICE_SPI
00022 
00023 #include "platform/PlatformMutex.h"
00024 #include "hal/spi_api.h"
00025 #include "platform/SingletonPtr.h"
00026 
00027 #if DEVICE_SPI_ASYNCH
00028 #include "platform/CThunk.h"
00029 #include "hal/dma_api.h"
00030 #include "platform/CircularBuffer.h"
00031 #include "platform/FunctionPointer.h"
00032 #include "platform/Transaction.h"
00033 #endif
00034 
00035 namespace mbed {
00036 /** \addtogroup drivers */
00037 /** @{*/
00038 
00039 /** A SPI Master, used for communicating with SPI slave devices
00040  *
00041  * The default format is set to 8-bits, mode 0, and a clock frequency of 1MHz
00042  *
00043  * Most SPI devices will also require Chip Select and Reset signals. These
00044  * can be controlled using <DigitalOut> pins
00045  *
00046  * @Note Synchronization level: Thread safe
00047  *
00048  * Example:
00049  * @code
00050  * // Send a byte to a SPI slave, and record the response
00051  *
00052  * #include "mbed.h"
00053  *
00054  * // hardware ssel (where applicable)
00055  * //SPI device(p5, p6, p7, p8); // mosi, miso, sclk, ssel
00056  *
00057  * // software ssel
00058  * SPI device(p5, p6, p7); // mosi, miso, sclk
00059  * DigitalOut cs(p8); // ssel
00060  *
00061  * int main() {
00062  *     // hardware ssel (where applicable)
00063  *     //int response = device.write(0xFF);
00064  *
00065  *     device.lock();
00066  *     // software ssel
00067  *     cs = 0;
00068  *     int response = device.write(0xFF);
00069  *     cs = 1;
00070  *     device.unlock();
00071  *
00072  * }
00073  * @endcode
00074  */
00075 class SPI {
00076 
00077 public:
00078 
00079     /** Create a SPI master connected to the specified pins
00080      *
00081      *  mosi or miso can be specfied as NC if not used
00082      *
00083      *  @param mosi SPI Master Out, Slave In pin
00084      *  @param miso SPI Master In, Slave Out pin
00085      *  @param sclk SPI Clock pin
00086      *  @param ssel SPI chip select pin
00087      */
00088     SPI(PinName mosi, PinName miso, PinName sclk, PinName ssel=NC);
00089 
00090     /** Configure the data transmission format
00091      *
00092      *  @param bits Number of bits per SPI frame (4 - 16)
00093      *  @param mode Clock polarity and phase mode (0 - 3)
00094      *
00095      * @code
00096      * mode | POL PHA
00097      * -----+--------
00098      *   0  |  0   0
00099      *   1  |  0   1
00100      *   2  |  1   0
00101      *   3  |  1   1
00102      * @endcode
00103      */
00104     void format(int bits, int mode = 0);
00105 
00106     /** Set the spi bus clock frequency
00107      *
00108      *  @param hz SCLK frequency in hz (default = 1MHz)
00109      */
00110     void frequency(int hz = 1000000);
00111 
00112     /** Write to the SPI Slave and return the response
00113      *
00114      *  @param value Data to be sent to the SPI slave
00115      *
00116      *  @returns
00117      *    Response from the SPI slave
00118     */
00119     virtual int write(int value);
00120 
00121     /** Acquire exclusive access to this SPI bus
00122      */
00123     virtual void lock(void);
00124 
00125     /** Release exclusive access to this SPI bus
00126      */
00127     virtual void unlock(void);
00128 
00129 #if DEVICE_SPI_ASYNCH
00130 
00131     /** Start non-blocking SPI transfer using 8bit buffers.
00132      *
00133      * @param tx_buffer The TX buffer with data to be transfered. If NULL is passed,
00134      *                  the default SPI value is sent
00135      * @param tx_length The length of TX buffer in bytes
00136      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
00137      *                  received data are ignored
00138      * @param rx_length The length of RX buffer in bytes
00139      * @param callback  The event callback function
00140      * @param event     The logical OR of events to modify. Look at spi hal header file for SPI events.
00141      * @return Zero if the transfer has started, or -1 if SPI peripheral is busy
00142      */
00143     template<typename Type>
00144     int transfer(const Type *tx_buffer, int tx_length, Type *rx_buffer, int rx_length, const event_callback_t& callback, int event = SPI_EVENT_COMPLETE) {
00145         if (spi_active(&_spi)) {
00146             return queue_transfer (tx_buffer, tx_length, rx_buffer, rx_length, sizeof(Type)*8, callback, event);
00147         }
00148         start_transfer(tx_buffer, tx_length, rx_buffer, rx_length, sizeof(Type)*8, callback, event);
00149         return 0;
00150     }
00151 
00152     /** Abort the on-going SPI transfer, and continue with transfer's in the queue if any.
00153      */
00154     void abort_transfer();
00155 
00156     /** Clear the transaction buffer
00157      */
00158     void clear_transfer_buffer();
00159 
00160     /** Clear the transaction buffer and abort on-going transfer.
00161      */
00162     void abort_all_transfers();
00163 
00164     /** Configure DMA usage suggestion for non-blocking transfers
00165      *
00166      *  @param usage The usage DMA hint for peripheral
00167      *  @return Zero if the usage was set, -1 if a transaction is on-going
00168     */
00169     int set_dma_usage(DMAUsage usage);
00170 
00171 protected:
00172     /** SPI IRQ handler
00173      *
00174     */
00175     void irq_handler_asynch(void);
00176 
00177     /** Common transfer method
00178      *
00179      * @param tx_buffer The TX buffer with data to be transfered. If NULL is passed,
00180      *                  the default SPI value is sent
00181      * @param tx_length The length of TX buffer in bytes
00182      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
00183      *                  received data are ignored
00184      * @param rx_length The length of RX buffer in bytes
00185      * @param bit_width The buffers element width
00186      * @param callback  The event callback function
00187      * @param event     The logical OR of events to modify
00188      * @return Zero if the transfer has started or was added to the queue, or -1 if SPI peripheral is busy/buffer is full
00189     */
00190     int transfer(const void *tx_buffer, int tx_length, void *rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t& callback, int event);
00191 
00192     /**
00193      *
00194      * @param tx_buffer The TX buffer with data to be transfered. If NULL is passed,
00195      *                  the default SPI value is sent
00196      * @param tx_length The length of TX buffer in bytes
00197      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
00198      *                  received data are ignored
00199      * @param rx_length The length of RX buffer in bytes
00200      * @param bit_width The buffers element width
00201      * @param callback  The event callback function
00202      * @param event     The logical OR of events to modify
00203      * @return Zero if a transfer was added to the queue, or -1 if the queue is full
00204     */
00205     int queue_transfer (const void *tx_buffer, int tx_length, void *rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t& callback, int event);
00206 
00207     /** Configures a callback, spi peripheral and initiate a new transfer
00208      *
00209      * @param tx_buffer The TX buffer with data to be transfered. If NULL is passed,
00210      *                  the default SPI value is sent
00211      * @param tx_length The length of TX buffer in bytes
00212      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
00213      *                  received data are ignored
00214      * @param rx_length The length of RX buffer in bytes
00215      * @param bit_width The buffers element width
00216      * @param callback  The event callback function
00217      * @param event     The logical OR of events to modify
00218     */
00219     void start_transfer(const void *tx_buffer, int tx_length, void *rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t& callback, int event);
00220 
00221 #if TRANSACTION_QUEUE_SIZE_SPI
00222 
00223     /** Start a new transaction
00224      *
00225      *  @param data Transaction data
00226     */
00227     void start_transaction(transaction_t *data);
00228 
00229     /** Dequeue a transaction
00230      *
00231     */
00232     void dequeue_transaction();
00233     static CircularBuffer<Transaction<SPI>, TRANSACTION_QUEUE_SIZE_SPI> _transaction_buffer;
00234 #endif
00235 
00236 #endif
00237 
00238 public:
00239     virtual ~SPI() {
00240     }
00241 
00242 protected:
00243     spi_t _spi;
00244 
00245 #if DEVICE_SPI_ASYNCH
00246     CThunk<SPI>  _irq;
00247     event_callback_t _callback;
00248     DMAUsage _usage;
00249 #endif
00250 
00251     void aquire(void);
00252     static SPI *_owner;
00253     static SingletonPtr<PlatformMutex>  _mutex;
00254     int _bits;
00255     int _mode;
00256     int _hz;
00257 };
00258 
00259 } // namespace mbed
00260 
00261 #endif
00262 
00263 #endif
00264 
00265 /** @}*/