Mbed OS Reference | SPI.h Source File

 /* mbed Microcontroller Library
  * Copyright (c) 2006-2019 ARM Limited
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 #ifndef MBED_SPI_H
 #define MBED_SPI_H
 
 #include "platform/platform.h"
 
 #if DEVICE_SPI || defined(DOXYGEN_ONLY)
 
 #include "platform/PlatformMutex.h"
 #include "hal/spi_api.h"
 #include "drivers/DigitalOut.h"
 #include "platform/SingletonPtr.h"
 #include "platform/NonCopyable.h"
 
 #if defined MBED_CONF_DRIVERS_SPI_COUNT_MAX && DEVICE_SPI_COUNT > MBED_CONF_DRIVERS_SPI_COUNT_MAX
 #define SPI_PERIPHERALS_USED MBED_CONF_DRIVERS_SPI_COUNT_MAX
 #elif defined DEVICE_SPI_COUNT
 #define SPI_PERIPHERALS_USED DEVICE_SPI_COUNT
 #else
 /* Backwards compatibility with HALs not providing DEVICE_SPI_COUNT */
 #define SPI_PERIPHERALS_USED 1
 #endif
 
 #if DEVICE_SPI_ASYNCH
 #include "platform/CThunk.h"
 #include "hal/dma_api.h"
 #include "platform/CircularBuffer.h"
 #include "platform/Callback.h"
 #include "platform/Transaction.h"
 #endif
 
 namespace mbed {
 /**
  * \defgroup drivers_SPI SPI class
  * \ingroup drivers-public-api-spi
  * @{
  */
 
 struct use_gpio_ssel_t { };
 const use_gpio_ssel_t use_gpio_ssel;
 
 /** A SPI Master, used for communicating with SPI slave devices.
  *
  * The default format is set to 8-bits, mode 0, and a clock frequency of 1MHz.
  *
  * Most SPI devices will also require Chip Select and Reset signals. These
  * can be controlled using DigitalOut pins.
  *
  * @note Synchronization level: Thread safe
  *
  * Example of how to send a byte to a SPI slave and record the response:
  * @code
  * #include "mbed.h"
  *
  * SPI device(SPI_MOSI, SPI_MISO, SPI_SCLK)
  *
  * DigitalOut chip_select(SPI_CS);
  *
  * int main() {
  *     device.lock();
  *     chip_select = 0;
  *
  *     int response = device.write(0xFF);
  *
  *     chip_select = 1;
  *     device.unlock();
  * }
  * @endcode
  *
  * Example using hardware Chip Select line:
  * @code
  * #include "mbed.h"
  *
  * SPI device(SPI_MOSI, SPI_MISO, SPI_SCLK, SPI_CS)
  *
  * int main() {
  *     device.lock();
  *     int response = device.write(0xFF);
  *     device.unlock();
  * }
  * @endcode
  */
 class SPI : private NonCopyable<SPI> {
 
 public:
 
     /** Create a SPI master connected to the specified pins.
      *
      *  @note This constructor passes the SSEL pin selection to the target HAL.
      *  Not all targets support SSEL, so this cannot be relied on in portable code.
      *  Portable code should use the alternative constructor that uses GPIO
      *  for SSEL.
      *
      *  @note You can specify mosi or miso as NC if not used.
      *
      *  @param mosi SPI Master Out, Slave In pin.
      *  @param miso SPI Master In, Slave Out pin.
      *  @param sclk SPI Clock pin.
      *  @param ssel SPI Chip Select pin.
      */
     SPI(PinName mosi, PinName miso, PinName sclk, PinName ssel = NC);
 
     /** Create a SPI master connected to the specified pins.
      *
      *  @note This constructor manipulates the SSEL pin as a GPIO output
      *  using a DigitalOut object. This should work on any target, and permits
      *  the use of select() and deselect() methods to keep the pin asserted
      *  between transfers.
      *
      *  @note You can specify mosi or miso as NC if not used.
      *
      *  @param mosi SPI Master Out, Slave In pin.
      *  @param miso SPI Master In, Slave Out pin.
      *  @param sclk SPI Clock pin.
      *  @param ssel SPI Chip Select pin.
      */
     SPI(PinName mosi, PinName miso, PinName sclk, PinName ssel, use_gpio_ssel_t);
 
     virtual ~SPI();
 
     /** Configure the data transmission format.
      *
      *  @param bits Number of bits per SPI frame (4 - 16).
      *  @param mode Clock polarity and phase mode (0 - 3).
      *
      * @code
      * mode | POL PHA
      * -----+--------
      *   0  |  0   0
      *   1  |  0   1
      *   2  |  1   0
      *   3  |  1   1
      * @endcode
      */
     void format(int bits, int mode = 0);
 
     /** Set the SPI bus clock frequency.
      *
      *  @param hz Clock frequency in Hz (default = 1MHz).
      */
     void frequency(int hz = 1000000);
 
     /** Write to the SPI Slave and return the response.
      *
      *  @param value Data to be sent to the SPI slave.
      *
      *  @return Response from the SPI slave.
      */
     virtual int write(int value);
 
     /** Write to the SPI Slave and obtain the response.
      *
      *  The total number of bytes sent and received will be the maximum of
      *  tx_length and rx_length. The bytes written will be padded with the
      *  value 0xff.
      *
      *  @param tx_buffer Pointer to the byte-array of data to write to the device.
      *  @param tx_length Number of bytes to write, may be zero.
      *  @param rx_buffer Pointer to the byte-array of data to read from the device.
      *  @param rx_length Number of bytes to read, may be zero.
      *  @return
      *      The number of bytes written and read from the device. This is
      *      maximum of tx_length and rx_length.
      */
     virtual int write(const char *tx_buffer, int tx_length, char *rx_buffer, int rx_length);
 
     /** Acquire exclusive access to this SPI bus.
      */
     virtual void lock(void);
 
     /** Release exclusive access to this SPI bus.
      */
     virtual void unlock(void);
 
     /** Assert the Slave Select line, acquiring exclusive access to this SPI bus.
      *
      * If use_gpio_ssel was not passed to the constructor, this only acquires
      * exclusive access; it cannot assert the Slave Select line.
      */
     void select(void);
 
     /** Deassert the Slave Select line, releasing exclusive access to this SPI bus.
      */
     void deselect(void);
 
     /** Set default write data.
       * SPI requires the master to send some data during a read operation.
       * Different devices may require different default byte values.
       * For example: A SD Card requires default bytes to be 0xFF.
       *
       * @param data Default character to be transmitted during a read operation.
       */
     void set_default_write_value(char data);
 
 #if DEVICE_SPI_ASYNCH
 
     /** Start non-blocking SPI transfer using 8bit buffers.
      *
      * This function locks the deep sleep until any event has occurred.
      *
      * @param tx_buffer The TX buffer with data to be transferred. If NULL is passed,
      *                  the default SPI value is sent.
      * @param tx_length The length of TX buffer in bytes.
      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
      *                  received data are ignored.
      * @param rx_length The length of RX buffer in bytes.
      * @param callback  The event callback function.
      * @param event     The event mask of events to modify. @see spi_api.h for SPI events.
      *
      * @return Operation result.
      * @retval 0 If the transfer has started.
      * @retval -1 If SPI peripheral is busy.
      */
     template<typename Type>
     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)
     {
         if (spi_active(&_peripheral->spi)) {
             return queue_transfer(tx_buffer, tx_length, rx_buffer, rx_length, sizeof(Type) * 8, callback, event);
         }
         start_transfer(tx_buffer, tx_length, rx_buffer, rx_length, sizeof(Type) * 8, callback, event);
         return 0;
     }
 
     /** Abort the on-going SPI transfer, and continue with transfers in the queue, if any.
      */
     void abort_transfer();
 
     /** Clear the queue of transfers.
      */
     void clear_transfer_buffer();
 
     /** Clear the queue of transfers and abort the on-going transfer.
      */
     void abort_all_transfers();
 
     /** Configure DMA usage suggestion for non-blocking transfers.
      *
      *  @param usage The usage DMA hint for peripheral.
      *
      *  @return Result of the operation.
      *  @retval 0 The usage was set.
      *  @retval -1 Usage cannot be set as there is an ongoing transaction.
      */
     int set_dma_usage(DMAUsage usage);
 
 #if !defined(DOXYGEN_ONLY)
 protected:
 
     /** SPI interrupt handler.
      */
     void irq_handler_asynch(void);
 
     /** Start the transfer or put it on the queue.
      *
      * @param tx_buffer The TX buffer with data to be transferred. If NULL is passed,
      *                  the default SPI value is sent
      * @param tx_length The length of TX buffer in bytes.
      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
      *                  received data are ignored.
      * @param rx_length The length of RX buffer in bytes.
      * @param bit_width The buffers element width in bits.
      * @param callback  The event callback function.
      * @param event     The event mask of events to modify.
      *
      * @return Operation success.
      * @retval 0 A transfer was started or added to the queue.
      * @retval -1 Transfer can't be added because queue is full.
      */
     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);
 
     /** Put a transfer on the transfer queue.
      *
      * @param tx_buffer The TX buffer with data to be transferred. If NULL is passed,
      *                  the default SPI value is sent.
      * @param tx_length The length of TX buffer in bytes.
      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
      *                  received data are ignored.
      * @param rx_length The length of RX buffer in bytes.
      * @param bit_width The buffers element width in bits.
      * @param callback  The event callback function.
      * @param event     The event mask of events to modify.
      *
      * @return Operation success.
      * @retval 0 A transfer was added to the queue.
      * @retval -1 Transfer can't be added because queue is full.
      */
     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);
 
     /** Configure a callback, SPI peripheral, and initiate a new transfer.
      *
      * @param tx_buffer The TX buffer with data to be transferred. If NULL is passed,
      *                  the default SPI value is sent.
      * @param tx_length The length of TX buffer in bytes.
      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
      *                  received data are ignored.
      * @param rx_length The length of RX buffer in bytes.
      * @param bit_width The buffers element width.
      * @param callback  The event callback function.
      * @param event     The event mask of events to modify.
      */
     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);
 
 private:
     /** Lock deep sleep only if it is not yet locked */
     void lock_deep_sleep();
 
     /** Unlock deep sleep in case it is locked */
     void unlock_deep_sleep();
 
 
 #if TRANSACTION_QUEUE_SIZE_SPI
     /** Start a new transaction.
      *
      *  @param data Transaction data.
      */
     void start_transaction(transaction_t *data);
 
     /** Dequeue a transaction and start the transfer if there was one pending.
      */
     void dequeue_transaction();
 
 #endif // TRANSACTION_QUEUE_SIZE_SPI
 #endif // !defined(DOXYGEN_ONLY)
 #endif // DEVICE_SPI_ASYNCH
 
 #if !defined(DOXYGEN_ONLY)
 protected:
 #ifdef DEVICE_SPI_COUNT
     // HAL must have defined this as a global enum
     typedef ::SPIName SPIName;
 #else
     // HAL may or may not have defined it - use a local definition
     enum SPIName { GlobalSPI };
 #endif
 
     // All members of spi_peripheral_s must be initialized to make the structure
     // constant-initialized, and hence able to be omitted by the linker,
     // as SingletonPtr now relies on C++ constant-initialization. (Previously it
     // worked through C++ zero-initialization). And all the constants should be zero
     // to ensure it stays in the actual zero-init part of the image if used, avoiding
     // an initialized-data cost.
     struct spi_peripheral_s {
         /* Internal SPI name identifying the resources. */
         SPIName name = SPIName(0);
         /* Internal SPI object handling the resources' state. */
         spi_t spi{};
         /* Used by lock and unlock for thread safety */
         SingletonPtr<PlatformMutex> mutex;
         /* Current user of the SPI */
         SPI *owner = nullptr;
 #if DEVICE_SPI_ASYNCH && TRANSACTION_QUEUE_SIZE_SPI
         /* Queue of pending transfers */
         SingletonPtr<CircularBuffer<Transaction<SPI>, TRANSACTION_QUEUE_SIZE_SPI> > transaction_buffer;
 #endif
     };
 
     // holds spi_peripheral_s per peripheral on the device.
     // Drawback: it costs ram size even if the device is not used, however
     // application can limit the allocation via JSON.
     static spi_peripheral_s _peripherals[SPI_PERIPHERALS_USED];
     static int _peripherals_used;
 
     // Holds the reference to the associated peripheral.
     spi_peripheral_s *_peripheral;
 
 #if DEVICE_SPI_ASYNCH
     /* Interrupt */
     CThunk<SPI> _irq;
     /* Interrupt handler callback */
     event_callback_t _callback;
     /* Current preferred DMA mode @see dma_api.h */
     DMAUsage _usage;
     /* Current sate of the sleep manager */
     bool _deep_sleep_locked;
 #endif // DEVICE_SPI_ASYNCH
 
     // Configuration.
     PinName _mosi;
     PinName _miso;
     PinName _sclk;
     PinName _hw_ssel;
 
     // The Slave Select GPIO if we're doing it ourselves.
     DigitalOut _sw_ssel;
 
     /* Size of the SPI frame */
     int _bits;
     /* Clock polairy and phase */
     int _mode;
     /* Clock frequency */
     int _hz;
     /* Default character used for NULL transfers */
     char _write_fill;
     /* Select count to handle re-entrant selection */
     int8_t _select_count;
 
 private:
     void _do_construct();
 
     /** Private acquire function without locking/unlocking.
      *  Implemented in order to avoid duplicate locking and boost performance.
      */
     void _acquire(void);
     void _set_ssel(int);
 
     /** Private lookup in the static _peripherals table.
      */
     static spi_peripheral_s *_lookup(SPIName name);
     /** Allocate an entry in the static _peripherals table.
      */
     static spi_peripheral_s *_alloc();
 
 #endif //!defined(DOXYGEN_ONLY)
 };
 
 /** @}*/
 
 } // namespace mbed
 
 #endif // DEVICE_SPI || DOXYGEN_ONLY
 
 #endif // MBED_SPI_H
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