//
// Created by dell on 24-12-20.
// Improved I2C driver with better state machine and error handling
//

#include "i2c.h"

/* Private variables */
static uint8_t i2c_retry_count = 0;

/*!
    \brief      configure the GPIO ports
    \param[in]  none
    \param[out] none
    \retval     none
*/
void i2c_gpio_config(void) {
    /* enable IIC GPIO clock */
    rcu_periph_clock_enable(RCU_GPIO_I2C);

    /* connect I2C_SCL_PIN to I2C_SCL */
    gpio_af_set(I2C_SCL_PORT, I2C_GPIO_AF, I2C_SCL_PIN);
    /* connect I2C_SDA_PIN to I2C_SDA */
    gpio_af_set(I2C_SDA_PORT, I2C_GPIO_AF, I2C_SDA_PIN);
    /* configure GPIO pins of I2C */
    gpio_mode_set(I2C_SCL_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP, I2C_SCL_PIN);
    gpio_output_options_set(I2C_SCL_PORT, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ, I2C_SCL_PIN);
    gpio_mode_set(I2C_SDA_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP, I2C_SDA_PIN);
    gpio_output_options_set(I2C_SDA_PORT, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ, I2C_SDA_PIN);
}

/*!
    \brief      configure the I2CX interface
    \param[in]  none
    \param[out] none
    \retval     i2c_status_t
*/
i2c_status_t i2c_config(void) {
    /* configure I2C GPIO */
    i2c_gpio_config();
    
    /* enable I2C clock */
    rcu_periph_clock_enable(RCU_I2C);
    
    /* configure I2C clock */
    i2c_clock_config(I2C0, I2C_SPEED, I2C_DTCY_2);
    
    /* configure I2C address - use 0x00 as master doesn't need specific address */
    i2c_mode_addr_config(I2C0, I2C_I2CMODE_ENABLE, I2C_ADDFORMAT_7BITS, I2C_MASTER_ADDRESS);
    
    /* enable I2CX */
    i2c_enable(I2C0);
    
    /* enable acknowledge */
    i2c_ack_config(I2C0, I2C_ACK_ENABLE);
    
    /* reset retry counter */
    i2c_retry_count = 0;
    
    return I2C_STATUS_SUCCESS;
}

/*!
    \brief      reset I2C bus with proper 9-clock recovery
    \param[in]  none
    \param[out] none
    \retval     i2c_status_t
*/
i2c_status_t i2c_bus_reset(void) {
    uint8_t i;
    
    /* disable I2C peripheral */
    i2c_disable(I2C0);
    i2c_deinit(I2C0);
    
    /* configure SDA/SCL as GPIO output for manual control */
    gpio_mode_set(I2C_SCL_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_PULLUP, I2C_SCL_PIN);
    gpio_mode_set(I2C_SDA_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_PULLUP, I2C_SDA_PIN);
    gpio_output_options_set(I2C_SCL_PORT, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ, I2C_SCL_PIN);
    gpio_output_options_set(I2C_SDA_PORT, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ, I2C_SDA_PIN);
    
    /* ensure both lines are high initially */
    gpio_bit_set(I2C_SCL_PORT, I2C_SCL_PIN);
    gpio_bit_set(I2C_SDA_PORT, I2C_SDA_PIN);
    delay_10us(I2C_DELAY_10US);
    
    /* generate 9 clock pulses to release any stuck slave */
    for (i = 0; i < I2C_RECOVERY_CLOCKS; i++) {
        gpio_bit_reset(I2C_SCL_PORT, I2C_SCL_PIN);
        delay_10us(I2C_DELAY_10US);
        gpio_bit_set(I2C_SCL_PORT, I2C_SCL_PIN);
        delay_10us(I2C_DELAY_10US);
    }
    
    /* generate stop condition */
    gpio_bit_reset(I2C_SDA_PORT, I2C_SDA_PIN);
    delay_10us(I2C_DELAY_10US);
    gpio_bit_set(I2C_SCL_PORT, I2C_SCL_PIN);
    delay_10us(I2C_DELAY_10US);
    gpio_bit_set(I2C_SDA_PORT, I2C_SDA_PIN);
    delay_10us(I2C_DELAY_10US);
    
    /* reconfigure as I2C pins */
    gpio_af_set(I2C_SCL_PORT, I2C_GPIO_AF, I2C_SCL_PIN);
    gpio_af_set(I2C_SDA_PORT, I2C_GPIO_AF, I2C_SDA_PIN);
    gpio_mode_set(I2C_SCL_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP, I2C_SCL_PIN);
    gpio_mode_set(I2C_SDA_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP, I2C_SDA_PIN);
    
    /* reconfigure the I2CX interface */
    return i2c_config();
}

/**
 * @brief 扫描I2C总线，查找连接的设备
 *
 * 该函数会扫描I2C总线上的所有地址（1到126），并尝试与每个地址进行通信。
 * 如果在某个地址上发现了设备，则会打印出该设备的地址。
 * 最后会打印出找到的设备总数。
 */
void i2c_scan(void) {
    uint32_t timeout;
    uint8_t address;
    int found_devices = 0;

    // printf("Scanning I2C bus...\r\n");
    const char* msg1 = "Scanning I2C bus...\r\n";
    for (uint8_t i = 0; msg1[i] != '\0'; i++) {
        while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
        usart_data_transmit(I2C_DEBUG_UART, msg1[i]);
    }
    while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TC) == RESET) {}

    for (address = 1; address < 127; address++) {
        timeout = 0;

        // 生成起始条件
        while (i2c_flag_get(I2C0, I2C_FLAG_I2CBSY) && (timeout < I2C_TIME_OUT))
            timeout++;
        if (timeout >= I2C_TIME_OUT) {
            continue; // 超时，跳过该地址
        }
        i2c_start_on_bus(I2C0);
        timeout = 0;

        // 等待起始条件发送完成
        while (!i2c_flag_get(I2C0, I2C_FLAG_SBSEND) && (timeout < I2C_TIME_OUT))
            timeout++;
        if (timeout >= I2C_TIME_OUT) {
            continue; // 超时，跳过该地址
        }
        i2c_master_addressing(I2C0, (address << 1), I2C_TRANSMITTER);
        timeout = 0;

        // 等待地址发送完成
        while (!i2c_flag_get(I2C0, I2C_FLAG_ADDSEND) && (timeout < I2C_TIME_OUT))
            timeout++;
        if (timeout < I2C_TIME_OUT) {
            i2c_flag_clear(I2C0, I2C_FLAG_ADDSEND);
            // printf("Found device at 0x%02X\r\n", address);
            const char* msg2_prefix = "Found device at 0x";
            for (uint8_t i = 0; msg2_prefix[i] != '\0'; i++) {
                while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
                usart_data_transmit(I2C_DEBUG_UART, msg2_prefix[i]);
            }
            // 发送地址的十六进制表示
            uint8_t hex_chars[] = "0123456789ABCDEF";
            while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
            usart_data_transmit(I2C_DEBUG_UART, hex_chars[(address >> 4) & 0x0F]);
            while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
            usart_data_transmit(I2C_DEBUG_UART, hex_chars[address & 0x0F]);
            const char* msg2_suffix = "\r\n";
            for (uint8_t i = 0; msg2_suffix[i] != '\0'; i++) {
                while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
                usart_data_transmit(I2C_DEBUG_UART, msg2_suffix[i]);
            }
            while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TC) == RESET) {}
            found_devices++;
        }

        // 生成停止条件
        i2c_stop_on_bus(I2C0);

        timeout = 0;

        while ((I2C_CTL0(I2C0) & I2C_CTL0_STOP) && (timeout < I2C_TIME_OUT))
            timeout++;
    }

    if (found_devices == 0) {
        // printf("No I2C devices found.\r\n");
        const char* msg3 = "No I2C devices found.\r\n";
        for (uint8_t i = 0; msg3[i] != '\0'; i++) {
            while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
            usart_data_transmit(I2C_DEBUG_UART, msg3[i]);
        }
        while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TC) == RESET) {}
    } else {
        // printf("Total %d I2C devices found.\r\n", found_devices);
        const char* msg4_prefix = "Total ";
        for (uint8_t i = 0; msg4_prefix[i] != '\0'; i++) {
            while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
            usart_data_transmit(I2C_DEBUG_UART, msg4_prefix[i]);
        }
        // 发送设备数量
        if (found_devices >= 10) {
            while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
            usart_data_transmit(I2C_DEBUG_UART, '0' + (found_devices / 10));
        }
        while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
        usart_data_transmit(I2C_DEBUG_UART, '0' + (found_devices % 10));
        const char* msg4_suffix = " I2C devices found.\r\n";
        for (uint8_t i = 0; msg4_suffix[i] != '\0'; i++) {
            while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
            usart_data_transmit(I2C_DEBUG_UART, msg4_suffix[i]);
        }
        while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TC) == RESET) {}
    }
}

/*!
    \brief      write 16-bit data to I2C device with improved state machine
    \param[in]  slave_addr: 7-bit slave address
    \param[in]  reg_addr: register address
    \param[in]  data: pointer to 2-byte data array
    \param[out] none
    \retval     i2c_status_t
*/
i2c_status_t i2c_write_16bits(uint8_t slave_addr, uint8_t reg_addr, const uint8_t data[2]) {
    i2c_state_t state = I2C_STATE_START;
    uint16_t timeout = 0;
    uint8_t data_index = 0;
    uint8_t retry_count = 0;

    /* Parameter validation */
    if (data == NULL || slave_addr > 0x7F) {
        return I2C_STATUS_INVALID_PARAM;
    }

    /* Enable acknowledge */
    i2c_ack_config(I2C0, I2C_ACK_ENABLE);

    while (retry_count < I2C_MAX_RETRY) {
        switch (state) {
            case I2C_STATE_START:
                timeout = 0;
                /* Wait for bus to be idle */
                while (i2c_flag_get(I2C0, I2C_FLAG_I2CBSY) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Send start condition */
                i2c_start_on_bus(I2C0);
                state = I2C_STATE_SEND_ADDRESS;
                timeout = 0;
                break;

            case I2C_STATE_SEND_ADDRESS:
                /* Wait for start condition to be sent */
                while ((!i2c_flag_get(I2C0, I2C_FLAG_SBSEND)) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Send slave address with write bit */
                i2c_master_addressing(I2C0, (slave_addr << 1), I2C_TRANSMITTER);
                state = I2C_STATE_CLEAR_ADDRESS;
                timeout = 0;
                break;

            case I2C_STATE_CLEAR_ADDRESS:
                /* Wait for address to be acknowledged */
                while ((!i2c_flag_get(I2C0, I2C_FLAG_ADDSEND)) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Clear address flag */
                i2c_flag_clear(I2C0, I2C_FLAG_ADDSEND);
                state = I2C_STATE_TRANSMIT_REG;
                timeout = 0;
                break;

            case I2C_STATE_TRANSMIT_REG:
                /* Wait for transmit buffer to be empty */
                while ((!i2c_flag_get(I2C0, I2C_FLAG_TBE)) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Send register address */
                i2c_data_transmit(I2C0, reg_addr);
                state = I2C_STATE_TRANSMIT_DATA;
                timeout = 0;
                data_index = 0;
                break;

            case I2C_STATE_TRANSMIT_DATA:
                /* Wait for byte transfer complete */
                while ((!i2c_flag_get(I2C0, I2C_FLAG_BTC)) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Send data bytes */
                if (data_index < 2) {
                    i2c_data_transmit(I2C0, data[data_index]);
                    data_index++;
                    timeout = 0;
                    /* Stay in this state until all data is sent */
                } else {
                    /* All data sent, proceed to stop */
                    state = I2C_STATE_STOP;
                    timeout = 0;
                }
                break;

            case I2C_STATE_STOP:
                /* Send stop condition */
                i2c_stop_on_bus(I2C0);

                /* Wait for stop condition to complete */
                while ((I2C_CTL0(I2C0) & I2C_CTL0_STOP) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Success */
                return I2C_STATUS_SUCCESS;

            case I2C_STATE_ERROR:
                /* Send stop condition to release bus */
                i2c_stop_on_bus(I2C0);

                /* Increment retry counter */
                retry_count++;
                if (retry_count >= I2C_MAX_RETRY) {
#ifdef DEBUG_VERBOSE
                    // printf("I2C write failed after %d retries\r\n", I2C_MAX_RETRY);
                    const char* msg5_prefix = "I2C write failed after ";
                    for (uint8_t i = 0; msg5_prefix[i] != '\0'; i++) {
                        while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
                        usart_data_transmit(I2C_DEBUG_UART, msg5_prefix[i]);
                    }
                    while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
                    usart_data_transmit(I2C_DEBUG_UART, '0' + I2C_MAX_RETRY);
                    const char* msg5_suffix = " retries\r\n";
                    for (uint8_t i = 0; msg5_suffix[i] != '\0'; i++) {
                        while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
                        usart_data_transmit(I2C_DEBUG_UART, msg5_suffix[i]);
                    }
                    while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TC) == RESET) {}
#endif
                    return I2C_STATUS_TIMEOUT;
                }

                /* Reset state machine for retry */
                state = I2C_STATE_START;
                timeout = 0;
                data_index = 0;

                /* Small delay before retry */
                delay_10us(10);
                break;

            default:
                state = I2C_STATE_ERROR;
                break;
        }
    }

    return I2C_STATUS_TIMEOUT;
}

/*!
    \brief      read 16-bit data from I2C device with improved state machine
    \param[in]  slave_addr: 7-bit slave address
    \param[in]  reg_addr: register address
    \param[out] data: pointer to 2-byte data buffer
    \retval     i2c_status_t
*/
i2c_status_t i2c_read_16bits(uint8_t slave_addr, uint8_t reg_addr, uint8_t *data) {
    i2c_state_t state = I2C_STATE_START;
    uint16_t timeout = 0;
    uint8_t data_index = 0;
    uint8_t retry_count = 0;
    bool write_phase = true;  /* First phase: write register address */

    /* Parameter validation */
    if (data == NULL || slave_addr > 0x7F) {
        return I2C_STATUS_INVALID_PARAM;
    }

    /* Enable acknowledge */
    i2c_ack_config(I2C0, I2C_ACK_ENABLE);

    while (retry_count < I2C_MAX_RETRY) {
        switch (state) {
            case I2C_STATE_START:
                timeout = 0;
                /* Wait for bus to be idle */
                while (i2c_flag_get(I2C0, I2C_FLAG_I2CBSY) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Configure ACK position for 2-byte read */
                if (!write_phase) {
                    i2c_ackpos_config(I2C0, I2C_ACKPOS_NEXT);
                }

                /* Send start condition */
                i2c_start_on_bus(I2C0);
                state = I2C_STATE_SEND_ADDRESS;
                timeout = 0;
                break;

            case I2C_STATE_SEND_ADDRESS:
                /* Wait for start condition to be sent */
                while ((!i2c_flag_get(I2C0, I2C_FLAG_SBSEND)) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Send slave address */
                if (write_phase) {
                    /* Write phase: send address with write bit */
                    i2c_master_addressing(I2C0, (slave_addr << 1), I2C_TRANSMITTER);
                } else {
                    /* Read phase: send address with read bit */
                    i2c_master_addressing(I2C0, (slave_addr << 1) | 0x01, I2C_RECEIVER);
                    /* Disable ACK for last byte */
                    i2c_ack_config(I2C0, I2C_ACK_DISABLE);
                }
                state = I2C_STATE_CLEAR_ADDRESS;
                timeout = 0;
                break;

            case I2C_STATE_CLEAR_ADDRESS:
                /* Wait for address to be acknowledged */
                while ((!i2c_flag_get(I2C0, I2C_FLAG_ADDSEND)) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Clear address flag */
                i2c_flag_clear(I2C0, I2C_FLAG_ADDSEND);

                if (write_phase) {
                    state = I2C_STATE_TRANSMIT_REG;
                } else {
                    /* For single byte read, send stop after clearing address */
                    if (data_index == 1) {
                        i2c_stop_on_bus(I2C0);
                    }
                    state = I2C_STATE_RECEIVE_DATA;
                    data_index = 0;
                }
                timeout = 0;
                break;

            case I2C_STATE_TRANSMIT_REG:
                /* Wait for transmit buffer to be empty */
                while ((!i2c_flag_get(I2C0, I2C_FLAG_TBE)) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Send register address */
                i2c_data_transmit(I2C0, reg_addr);
                state = I2C_STATE_RESTART;
                timeout = 0;
                break;

            case I2C_STATE_RESTART:
                /* Wait for byte transfer complete */
                while ((!i2c_flag_get(I2C0, I2C_FLAG_BTC)) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Switch to read phase */
                write_phase = false;
                state = I2C_STATE_START;
                timeout = 0;
                break;

            case I2C_STATE_RECEIVE_DATA:
                if (data_index < 2) {
                    if (data_index == 1) {
                        /* Wait for BTC before sending stop for last byte */
                        while ((!i2c_flag_get(I2C0, I2C_FLAG_BTC)) && (timeout < I2C_TIME_OUT)) {
                            timeout++;
                        }
                        if (timeout >= I2C_TIME_OUT) {
                            state = I2C_STATE_ERROR;
                            break;
                        }
                        /* Send stop condition before reading last byte */
                        i2c_stop_on_bus(I2C0);
                    }

                    /* Wait for receive buffer not empty */
                    while ((!i2c_flag_get(I2C0, I2C_FLAG_RBNE)) && (timeout < I2C_TIME_OUT)) {
                        timeout++;
                    }
                    if (timeout >= I2C_TIME_OUT) {
                        state = I2C_STATE_ERROR;
                        break;
                    }

                    /* Read data byte */
                    data[data_index] = i2c_data_receive(I2C0);
                    data_index++;
                    timeout = 0;

                    if (data_index >= 2) {
                        state = I2C_STATE_STOP;
                    }
                } else {
                    state = I2C_STATE_STOP;
                }
                break;

            case I2C_STATE_STOP:
                /* Wait for stop condition to complete */
                while ((I2C_CTL0(I2C0) & I2C_CTL0_STOP) && (timeout < I2C_TIME_OUT)) {
                    timeout++;
                }
                if (timeout >= I2C_TIME_OUT) {
                    state = I2C_STATE_ERROR;
                    break;
                }

                /* Success */
                return I2C_STATUS_SUCCESS;

            case I2C_STATE_ERROR:
                /* Send stop condition to release bus */
                i2c_stop_on_bus(I2C0);

                /* Increment retry counter */
                retry_count++;
                if (retry_count >= I2C_MAX_RETRY) {
#ifdef DEBUG_VERBOSE
                    // printf("I2C read failed after %d retries\r\n", I2C_MAX_RETRY);
                    const char* msg6_prefix = "I2C read failed after ";
                    for (uint8_t i = 0; msg6_prefix[i] != '\0'; i++) {
                        while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
                        usart_data_transmit(I2C_DEBUG_UART, msg6_prefix[i]);
                    }
                    while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
                    usart_data_transmit(I2C_DEBUG_UART, '0' + I2C_MAX_RETRY);
                    const char* msg6_suffix = " retries\r\n";
                    for (uint8_t i = 0; msg6_suffix[i] != '\0'; i++) {
                        while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TBE) == RESET) {}
                        usart_data_transmit(I2C_DEBUG_UART, msg6_suffix[i]);
                    }
                    while (usart_flag_get(I2C_DEBUG_UART, USART_FLAG_TC) == RESET) {}
#endif
                    return I2C_STATUS_TIMEOUT;
                }

                /* Reset state machine for retry */
                state = I2C_STATE_START;
                write_phase = true;
                timeout = 0;
                data_index = 0;

                /* Small delay before retry */
                delay_10us(10);
                break;

            default:
                state = I2C_STATE_ERROR;
                break;
        }
    }

    return I2C_STATUS_TIMEOUT;
}

/*!
    \brief      get status string for debugging
    \param[in]  status: i2c_status_t value
    \param[out] none
    \retval     const char* status string
*/
const char* i2c_get_status_string(i2c_status_t status) {
    switch (status) {
        case I2C_STATUS_SUCCESS:
            return "SUCCESS";
        case I2C_STATUS_TIMEOUT:
            return "TIMEOUT";
        case I2C_STATUS_NACK:
            return "NACK";
        case I2C_STATUS_BUS_BUSY:
            return "BUS_BUSY";
        case I2C_STATUS_ERROR:
            return "ERROR";
        case I2C_STATUS_INVALID_PARAM:
            return "INVALID_PARAM";
        default:
            return "UNKNOWN";
    }
}