SMBus.hpp

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/**
 * @file SMBus.hpp
 * SMBus v2.0 protocol implementation.
 *
 * @author Jacob Dahl <dahl.jakejacob@gmail.com>
 */

#include <drivers/device/i2c.h>

#include <string.h>

#define SMBUS_PEC_POLYNOMIAL    0x07    ///< Polynomial for calculating PEC

class SMBus : public device::I2C
{
public:
    SMBus(int bus_num, uint16_t address);
    ~SMBus() override = default;

    /**
     * @brief Sends a block write command.
     * @param cmd_code The command code.
     * @param data The data to be written.
     * @param length The number of bytes being written.
     * @return Returns PX4_OK on success, -errno on failure.
     */
    int block_write(const uint8_t cmd_code, void *data, uint8_t byte_count, bool use_pec);

    /**
     * @brief Sends a block read command.
     * @param cmd_code The command code.
     * @param data The returned data.
     * @param length The number of bytes being read
     * @return Returns PX4_OK on success, -errno on failure.
     */
    int block_read(const uint8_t cmd_code, void *data, const uint8_t length, bool use_pec);

    /**
     * @brief Sends a read word command.
     * @param cmd_code The command code.
     * @param data The 2 bytes of returned data plus a 1 byte CRC if used.
     * @return Returns PX4_OK on success, -errno on failure.
     */
    int read_word(const uint8_t cmd_code, uint16_t &data);

    /**
     * @brief Sends a write word command.
     * @param cmd_code The command code.
     * @param data The 2 bytes of data to be transfered.
     * @return Returns PX4_OK on success, -errno on failure.
     */
    int write_word(const uint8_t cmd_code, uint16_t data);

    /**
     * @brief Calculates the PEC from the data.
     * @param buffer The buffer that stores the data to perform the CRC over.
     * @param length The number of bytes being written.
     * @return Returns PX4_OK on success, -errno on failure.
     */
    uint8_t get_pec(uint8_t *buffer, uint8_t length);

};