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