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