app_twi.h

/**
 * Copyright (c) 2015 - 2017, Nordic Semiconductor ASA
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 * 
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 * 
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 * 
 * 5. Any software provided in binary form under this license must not be reverse
 *    engineered, decompiled, modified and/or disassembled.
 * 
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 */
#ifndef APP_TWI_H__
#define APP_TWI_H__

#include <stdint.h>
#include "nrf_drv_twi.h"
#include "sdk_errors.h"
#include "nrf_queue.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @defgroup app_twi TWI transaction manager
 * @{
 * @ingroup app_common
 *
 * @brief Module for scheduling TWI transactions.
 */

/**
 * @brief Flag indicating that a given transfer should not be ended
 *        with a stop condition.
 *
 * Use this flag when a stop condition is undesirable between two transfers,
 * for example, when the first transfer is a write that sets an address in the slave
 * device and the second one is a read that fetches certain data using this
 * address. In this case, the second transfer should follow directly after the
 * first transfer, with a repeated start condition instead of a stop and then
 * a new start condition.
 */
#define APP_TWI_NO_STOP     0x01

/**
 * @brief Macro for creating a write transfer.
 *
 * @param[in] address Slave address.
 * @param[in] p_data  Pointer to the data to be sent.
 * @param[in] length  Number of bytes to transfer.
 * @param[in] flags   Transfer flags (see @ref APP_TWI_NO_STOP).
 */
#define APP_TWI_WRITE(address, p_data, length, flags) \
    APP_TWI_TRANSFER(APP_TWI_WRITE_OP(address), p_data, length, flags)

/**
 * @brief Macro for creating a read transfer.
 *
 * @param     address Slave address.
 * @param[in] p_data  Pointer to the buffer where received data should be placed.
 * @param     length  Number of bytes to transfer.
 * @param     flags   Transfer flags (see @ref APP_TWI_NO_STOP).
 */
#define APP_TWI_READ(address, p_data, length, flags) \
    APP_TWI_TRANSFER(APP_TWI_READ_OP(address), p_data, length, flags)

/**
 * @brief Helper macro, should not be used directly.
 */
#define APP_TWI_TRANSFER(_operation, _p_data, _length, _flags) \
{                                      \
    .p_data    = (uint8_t *)(_p_data), \
    .length    = _length,              \
    .operation = _operation,           \
    .flags     = _flags                \
}
/**
 * @brief Helper macro, should not be used directly.
 */
#define APP_TWI_WRITE_OP(address)      (((address) << 1) | 0)
/**
 * @brief Helper macro, should not be used directly.
 */
#define APP_TWI_READ_OP(address)       (((address) << 1) | 1)
/**
 * @brief Helper macro, should not be used directly.
 */
#define APP_TWI_IS_READ_OP(operation)  ((operation) & 1)
/**
 * @brief Helper macro, should not be used directly.
 */
#define APP_TWI_OP_ADDRESS(operation)  ((operation) >> 1)

/**
 * @brief TWI transaction callback prototype.
 *
 * @param     result      Result of operation (NRF_SUCCESS on success,
 *                        otherwise a relevant error code).
 * @param[in] p_user_data Pointer to user data defined in transaction
 *                        descriptor.
 */
typedef void (* app_twi_callback_t)(ret_code_t result, void * p_user_data);

/**
 * @brief TWI transfer descriptor.
 */
typedef struct {
    uint8_t * p_data;     ///< Pointer to the buffer holding the data.
    uint8_t   length;     ///< Number of bytes to transfer.
    uint8_t   operation;  ///< Device address combined with transfer direction.
    uint8_t   flags;      ///< Transfer flags (see @ref APP_TWI_NO_STOP).
} app_twi_transfer_t;

/**
 * @brief TWI transaction descriptor.
 */
typedef struct {
    app_twi_callback_t              callback;
    ///< User-specified function to be called after the transaction is finished.

    void *                          p_user_data;
    ///< Pointer to user data to be passed to the callback.

    app_twi_transfer_t const *      p_transfers;
    ///< Pointer to the array of transfers that make up the transaction.

    uint8_t                         number_of_transfers;
    ///< Number of transfers that make up the transaction.

    nrf_drv_twi_config_t const *    p_required_twi_cfg;
    ///< Pointer to instance hardware configuration.
} app_twi_transaction_t;

/**
 * @brief TWI instance control block.
 */
typedef struct {
    app_twi_transaction_t const * volatile p_current_transaction;
    ///< Currently realized transaction.

    nrf_drv_twi_config_t default_configuration;
    ///< Default hardware configuration.

    nrf_drv_twi_config_t const * p_current_configuration;
    ///< Pointer to current hardware configuration.

    uint8_t volatile current_transfer_idx;
    ///< Index of currently performed transfer (within current transaction).

    bool volatile internal_transaction_in_progress;
    ///< Informs that an internal transaction is being performed (by app_twi_perform()).

    uint8_t volatile internal_transaction_result;
    ///< Used to pass the result of the internal transaction realized by app_twi_perform().
}app_twi_cb_t;

/**
 * @brief TWI transaction manager instance.
 */
typedef struct {
    app_twi_cb_t * p_app_twi_cb;
    ///< Control block of instance.

    nrf_queue_t const * p_queue;
    ///< Transaction queue.

    nrf_drv_twi_t twi;
    ///< Pointer to TWI master driver instance.
} app_twi_t;

/**
 * @brief Macro that simplifies defining a TWI transaction manager
 *        instance.
 *
 * This macro allocates a static buffer for the transaction queue.
 * Therefore, it should be used in only one place in the code for a given
 * instance.
 *
 * @note The queue size is the maximum number of pending transactions
 *       not counting the one that is currently realized. This means that
 *       for an empty queue with size of, for example, 4 elements, it is
 *       possible to schedule up to 5 transactions.
 *
 * @param[in]  _app_twi_name    Name of instance to be created.
 * @param[in]  _queue_size       Size of the transaction queue (maximum number
 *                              of pending transactions).
 * @param[in]  _twi_idx          Index of hardware TWI instance to be used.
 */
#define APP_TWI_DEF(_app_twi_name, _queue_size, _twi_idx) \
    NRF_QUEUE_DEF(app_twi_transaction_t const *,                                            \
                 _app_twi_name##_queue,                                                     \
                 (_queue_size),                                                             \
                 NRF_QUEUE_MODE_NO_OVERFLOW);                                               \
    static app_twi_cb_t CONCAT_2(_app_twi_name, _cb);                                       \
    static const app_twi_t _app_twi_name =                                                  \
    {                                                                                       \
        .p_app_twi_cb               = &CONCAT_2(_app_twi_name, _cb),                        \
        .p_queue                    = &_app_twi_name##_queue,                               \
        .twi                        = NRF_DRV_TWI_INSTANCE(_twi_idx)                        \
    }

/**
 * @brief Function for initializing a TWI transaction manager instance.
 *
 * @param[in] p_app_twi                 Pointer to the instance to be initialized.
 * @param[in] p_default_twi_config     Pointer to the TWI master driver configuration. This configuration
 *                                      will be used whenever the scheduled transaction will have
 *                                      p_twi_configuration set to NULL value.
 *
 * @return Values returned by the @ref nrf_drv_twi_init function.
 */
ret_code_t app_twi_init(app_twi_t const *               p_app_twi,
                        nrf_drv_twi_config_t const *    p_default_twi_config);

/**
 * @brief Function for uninitializing a TWI transaction manager instance.
 *
 * @param[in] p_app_twi Pointer to the instance to be uninitialized.
 */
void app_twi_uninit(app_twi_t const * p_app_twi);

/**
 * @brief Function for scheduling a TWI transaction.
 *
 * The transaction is enqueued and started as soon as the TWI bus is
 * available, thus when all previously scheduled transactions have been
 * finished (possibly immediately).
 *
 * @note If @ref app_twi_transaction_t::p_required_twi_cfg
 *       is set to a non-NULL value the module will compare it with
 *       @ref app_twi_cb_t::p_current_configuration and reinitialize hardware
 *       TWI instance with new parameters if any differences are found.
 *       If @ref app_twi_transaction_t::p_required_twi_cfg is set to NULL then
 *       it will treat it as it would be set to @ref app_twi_cb_t::default_configuration.
 *
 * @param[in] p_app_twi     Pointer to the TWI transaction manager instance.
 * @param[in] p_transaction Pointer to the descriptor of the transaction to be
 *                          scheduled.
 *
 * @retval NRF_SUCCESS      If the transaction has been successfully scheduled.
 * @retval NRF_ERROR_NO_MEM If the queue is full (Only if queue in
 *                          @ref NRF_QUEUE_MODE_NO_OVERFLOW).
 */
ret_code_t app_twi_schedule(app_twi_t const *             p_app_twi,
                            app_twi_transaction_t const * p_transaction);

/**
 * @brief Function for scheduling a transaction and waiting until it is finished.
 *
 * This function schedules a transaction that consists of one or more transfers
 * and waits until it is finished.
 *
 * @param[in] p_app_twi           Pointer to the TWI transaction manager instance.
 * @param[in] p_transfers         Pointer to an array of transfers to be performed.
 * @param     number_of_transfers Number of transfers to be performed.
 * @param     user_function       User-specified function to be called while
 *                                waiting. NULL if such functionality
 *                                is not needed.
 *
 * @retval NRF_SUCCESS    If the transfers have been successfully realized.
 * @retval NRF_ERROR_BUSY If some transfers are already being performed.
 * @retval -              Other error codes mean that the transaction has ended
 *                        with the error that is specified in the error code.
 */
ret_code_t app_twi_perform(app_twi_t const *          p_app_twi,
                           app_twi_transfer_t const * p_transfers,
                           uint8_t                    number_of_transfers,
                           void (* user_function)(void));

/**
 * @brief Function for getting the current state of a TWI transaction manager
 *        instance.
 *
 * @param[in] p_app_twi Pointer to the TWI transaction manager instance.
 *
 * @retval true  If all scheduled transactions have been finished.
 * @retval false Otherwise.
 */
__STATIC_INLINE bool app_twi_is_idle(app_twi_t const * p_app_twi)
{
    return (p_app_twi->p_app_twi_cb->p_current_transaction == NULL);
}

/**
 *@}
 **/


#ifdef __cplusplus
}
#endif

#endif // APP_TWI_H__