/**************************************************************************** * drivers/sensors/sht4x.c * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. The * ASF licenses this file to you 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include #if defined(CONFIG_I2C) && defined(CONFIG_SENSORS_SHT4X) /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #ifdef CONFIG_SHT4X_DEBUG #define sht4x_dbg(x, ...) _info(x, ##__VA_ARGS__) #endif #if defined(CONFIG_SHT4X_FAHRENHEIT) #define SHT4X_TEMP_UNIT "F" #else #define SHT4X_TEMP_UNIT "C" #endif // defined(CONFIG_SHT4X_FAHRENHEIT) #ifndef CONFIG_SHT4X_I2C_FREQUENCY #define CONFIG_SHT4X_I2C_FREQUENCY 400000 #endif // CONFIG_SHT4X_I2C_FREQUENCY #define SHT4X_CRC_INIT 0xFF /* Initial value of the calculated CRC. */ #define SHT4X_CRC_POLY 0x31 /* CRC calculation polynomial. */ #define SHT4X_SOFT_RESET 0x94 /* Soft reset command. */ #define SHT4X_READ_SERIAL 0x89 /* Read serial number command. */ #define SHT4X_READ_LOW_PREC 0xE0 /* Low precision read temp & humidity. */ #define SHT4X_READ_MED_PREC 0xF6 /* Med precision read temp & humidity. */ #define SHT4X_READ_HIGH_PREC 0xFD /* High precision read temp & humidity. */ #define SHT4X_HEAT_200_1 0x39 /* Activate heater with 200mW for 1s. */ #define SHT4X_HEAT_200_P1 0x32 /* Activate heater with 200mW for 0.1s. */ #define SHT4X_HEAT_110_1 0x2F /* Activate heater with 110mW for 1s. */ #define SHT4X_HEAT_110_P1 0x24 /* Activate heater with 110mW for 0.1s. */ #define SHT4X_HEAT_20_1 0x1E /* Activate heater with 20mW for 1s. */ #define SHT4X_HEAT_20_P1 0x15 /* Activate heater with 20mW for 0.1s. */ /**************************************************************************** * Private ****************************************************************************/ struct sht4x_dev_s { FAR struct i2c_master_s *i2c; /* I2C interface. */ uint8_t addr; /* I2C address. */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS bool unlinked; /* True, driver has been unlinked. */ #endif // CONFIG_DISABLE_PSEUDOFS_OPERATIONS struct timespec last_heat; /* Last time heater was active. */ enum sht4x_precision_e precision; /* The precision for read operations. */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS int16_t crefs; /* Number of open references. */ #endif // CONFIG_DISABLE_PSEUDOFS_OPERATIONS mutex_t devlock; }; /* Easy unpacking of serial number from I2C packet. */ union sht4x_serialno_t { uint32_t full; /* Full serial number. */ struct { uint16_t msb; /* Most significant 2 bytes. */ uint16_t lsb; /* Least significant 2 bytes. */ } halves; }; /**************************************************************************** * Private Data ****************************************************************************/ /* Commands for reading at different precisions */ static const uint8_t g_precision_read[] = { [SHT4X_PREC_LOW] = SHT4X_READ_LOW_PREC, [SHT4X_PREC_MED] = SHT4X_READ_MED_PREC, [SHT4X_PREC_HIGH] = SHT4X_READ_HIGH_PREC, }; #ifdef CONFIG_SHT4X_CRC_LOOKUP /* CRC lookup table. */ static const uint8_t g_crc_lookup[] = { 0x0, 0x31, 0x62, 0x53, 0xc4, 0xf5, 0xa6, 0x97, 0xb9, 0x88, 0xdb, 0xea, 0x7d, 0x4c, 0x1f, 0x2e, 0x43, 0x72, 0x21, 0x10, 0x87, 0xb6, 0xe5, 0xd4, 0xfa, 0xcb, 0x98, 0xa9, 0x3e, 0xf, 0x5c, 0x6d, 0x86, 0xb7, 0xe4, 0xd5, 0x42, 0x73, 0x20, 0x11, 0x3f, 0xe, 0x5d, 0x6c, 0xfb, 0xca, 0x99, 0xa8, 0xc5, 0xf4, 0xa7, 0x96, 0x1, 0x30, 0x63, 0x52, 0x7c, 0x4d, 0x1e, 0x2f, 0xb8, 0x89, 0xda, 0xeb, 0x3d, 0xc, 0x5f, 0x6e, 0xf9, 0xc8, 0x9b, 0xaa, 0x84, 0xb5, 0xe6, 0xd7, 0x40, 0x71, 0x22, 0x13, 0x7e, 0x4f, 0x1c, 0x2d, 0xba, 0x8b, 0xd8, 0xe9, 0xc7, 0xf6, 0xa5, 0x94, 0x3, 0x32, 0x61, 0x50, 0xbb, 0x8a, 0xd9, 0xe8, 0x7f, 0x4e, 0x1d, 0x2c, 0x2, 0x33, 0x60, 0x51, 0xc6, 0xf7, 0xa4, 0x95, 0xf8, 0xc9, 0x9a, 0xab, 0x3c, 0xd, 0x5e, 0x6f, 0x41, 0x70, 0x23, 0x12, 0x85, 0xb4, 0xe7, 0xd6, 0x7a, 0x4b, 0x18, 0x29, 0xbe, 0x8f, 0xdc, 0xed, 0xc3, 0xf2, 0xa1, 0x90, 0x7, 0x36, 0x65, 0x54, 0x39, 0x8, 0x5b, 0x6a, 0xfd, 0xcc, 0x9f, 0xae, 0x80, 0xb1, 0xe2, 0xd3, 0x44, 0x75, 0x26, 0x17, 0xfc, 0xcd, 0x9e, 0xaf, 0x38, 0x9, 0x5a, 0x6b, 0x45, 0x74, 0x27, 0x16, 0x81, 0xb0, 0xe3, 0xd2, 0xbf, 0x8e, 0xdd, 0xec, 0x7b, 0x4a, 0x19, 0x28, 0x6, 0x37, 0x64, 0x55, 0xc2, 0xf3, 0xa0, 0x91, 0x47, 0x76, 0x25, 0x14, 0x83, 0xb2, 0xe1, 0xd0, 0xfe, 0xcf, 0x9c, 0xad, 0x3a, 0xb, 0x58, 0x69, 0x4, 0x35, 0x66, 0x57, 0xc0, 0xf1, 0xa2, 0x93, 0xbd, 0x8c, 0xdf, 0xee, 0x79, 0x48, 0x1b, 0x2a, 0xc1, 0xf0, 0xa3, 0x92, 0x5, 0x34, 0x67, 0x56, 0x78, 0x49, 0x1a, 0x2b, 0xbc, 0x8d, 0xde, 0xef, 0x82, 0xb3, 0xe0, 0xd1, 0x46, 0x77, 0x24, 0x15, 0x3b, 0xa, 0x59, 0x68, 0xff, 0xce, 0x9d, 0xac, } #endif // CONFIG_SHT4X_CRC_LOOKUP /* Measurement times for the various precisions, in microseconds. */ static const uint16_t g_measurement_times[] = { [SHT4X_PREC_LOW] = 1600, [SHT4X_PREC_MED] = 4500, [SHT4X_PREC_HIGH] = 8300, }; /* Commands for the various heating options. */ static const uint8_t g_heat_cmds[] = { [SHT4X_HEATER_200MW_1] = SHT4X_HEAT_200_1, [SHT4X_HEATER_200MW_01] = SHT4X_HEAT_200_P1, [SHT4X_HEATER_110MW_1] = SHT4X_HEAT_110_1, [SHT4X_HEATER_110MW_01] = SHT4X_HEAT_110_P1, [SHT4X_HEATER_20MW_1] = SHT4X_HEAT_20_1, [SHT4X_HEATER_20MW_01] = SHT4X_HEAT_20_P1, }; /* Timeouts for the various heating options in microseconds. */ static const uint32_t g_heat_times[] = { [SHT4X_HEATER_200MW_1] = 1000000, [SHT4X_HEATER_200MW_01] = 100000, [SHT4X_HEATER_110MW_1] = 1000000, [SHT4X_HEATER_110MW_01] = 100000, [SHT4X_HEATER_20MW_1] = 1000000, [SHT4X_HEATER_20MW_01] = 100000, }; /**************************************************************************** * Private Function Prototypes ****************************************************************************/ static int sht4x_open(FAR struct file *filep); static int sht4x_close(FAR struct file *filep); static ssize_t sht4x_write(FAR struct file *filep, FAR const char *buffer, size_t buflen); static ssize_t sht4x_read(FAR struct file *filep, FAR char *buffer, size_t buflen); static int sht4x_ioctl(FAR struct file *filep, int cmd, unsigned long arg); static int sht4x_unlink(FAR struct inode *inode); /**************************************************************************** * Private Data ****************************************************************************/ static const struct file_operations g_sht4xfops = { #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS .open = sht4x_open, .close = sht4x_close, #else .open = NULL, .close = NULL, #endif .read = sht4x_read, .write = sht4x_write, .seek = NULL, .ioctl = sht4x_ioctl, .mmap = NULL, .truncate = NULL, .poll = NULL, #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS .unlink = sht4x_unlink, #endif }; /**************************************************************************** * Private Functions ****************************************************************************/ #ifdef CONFIG_SHT4X_CRC_LOOKUP /**************************************************************************** * Name: sht4x_crc_lookup * * Description: * Perform a CRC calculation using the lookup table. * ****************************************************************************/ uint8_t sht4x_crc_lookup(const uint8_t *buf, uint8_t nbytes) { uint8_t crc = SHT4X_CRC_INIT; for (uint8_t byte = 0; byte < nbytes; byte++) { crc = g_crc_lookup[crc ^ buf[byte]]; } return crc; } #endif /**************************************************************************** * Name: sht4x_crc_bitwise * * Description: * Perform a CRC calculation using the bitwise calculation. * ****************************************************************************/ uint8_t sht4x_crc_bitwise(const uint8_t *buf, uint8_t nbytes) { uint8_t crc = SHT4X_CRC_INIT; for (uint8_t byte = 0; byte < nbytes; byte++) { crc ^= buf[byte]; for (uint8_t bit = 0; bit < 8; bit++) { if (crc & 0x80) { /* Discard the highest bit (implicit XOR), then divide by the * polynomial. */ crc <<= 1; crc ^= SHT4X_CRC_POLY; } else { /* Continue until the highest bit is set. */ crc <<= 1; } } } return crc; } /**************************************************************************** * Name: sht4x_crc * * Description: * Perform a CRC calculation on the data to check for validity. * The `buf` param must be a data buffer that ends with its own 8 bit CRC. * The `nbytes` param is the length of the data including the 8 bit CRC. * ****************************************************************************/ static int sht4x_crc(const uint8_t *buf, uint8_t nbytes) { #ifdef CONFIG_SHT4X_CRC_LOOKUP if (sht4x_crc_lookup(buf, nbytes) != 0) { return -EBADMSG; } #else if (sht4x_crc_bitwise(buf, nbytes) != 0) { return -EBADMSG; } #endif return 0; } /**************************************************************************** * Name: sht4x_cmd * * Description: * I2C access helper for sending commands to the SHT4x which receive data * in response. * ****************************************************************************/ static int sht4x_cmd(FAR struct sht4x_dev_s *priv, uint8_t command, uint32_t timeout, uint16_t *data1, uint16_t *data2) { struct i2c_msg_s cmd; struct i2c_msg_s read_data; int err; /* 2 byte data, 1 byte CRC, 2 byte data, 1 byte CRC. */ uint8_t combined_data[6]; cmd.frequency = CONFIG_SHT4X_I2C_FREQUENCY; cmd.addr = priv->addr; cmd.flags = 0; cmd.buffer = &command; cmd.length = sizeof(command); /* Trigger measurement. */ err = I2C_TRANSFER(priv->i2c, &cmd, 1); if (err < 0) { return err; } /* Wait for measurement to complete. Serial number command does not require * wait time. */ if (timeout > 0) { usleep(timeout); } read_data.frequency = CONFIG_SHT4X_I2C_FREQUENCY; read_data.addr = priv->addr; read_data.flags = I2C_M_READ; read_data.buffer = combined_data; read_data.length = sizeof(combined_data); err = I2C_TRANSFER(priv->i2c, &read_data, 1); if (err < 0) { return err; } /* Check CRC for first data packet */ err = sht4x_crc(combined_data, 3); if (err < 0) { return err; } /* Check CRC for second data packet */ err = sht4x_crc(combined_data + 3, 3); if (err < 0) { return err; } *data1 = (uint16_t)(combined_data[0] << 8) | combined_data[1]; *data2 = (uint16_t)(combined_data[3] << 8) | combined_data[4]; return err; } /**************************************************************************** * Name: sht4x_reset * * Description: * Perform a soft reset of the sensor. WARNING: Sensor is not available * until 1ms after this command is sent. * ****************************************************************************/ static int sht4x_reset(FAR struct sht4x_dev_s *priv) { struct i2c_msg_s msg[1]; uint8_t reset_cmd = SHT4X_SOFT_RESET; msg[0].frequency = CONFIG_SHT4X_I2C_FREQUENCY; msg[0].addr = priv->addr; msg[0].flags = 0; msg[0].buffer = &reset_cmd; msg[0].length = sizeof(reset_cmd); return I2C_TRANSFER(priv->i2c, msg, 1); } /**************************************************************************** * Name: sht4x_calc_temp * * Description: * Calculate the temperature from the SHT4X raw data. * ****************************************************************************/ static int32_t sht4x_calc_temp(uint16_t temp) { #ifdef CONFIG_SHT4X_FAHRENHEIT /* Millidegrees Fahrenheit */ return -49000 + 315 * ((temp * 1000) / 65535); #else return -45000 + 175 * ((temp * 1000) / 65535); /* Millidegrees Celsius */ #endif // CONFIG_SHT4X_FAHRENHEIT } /**************************************************************************** * Name: sht4x_calc_hum * * Description: * Calculate the humidity from the SHT4X raw data. * ****************************************************************************/ static int16_t sht4x_calc_hum(uint16_t humidity) { int16_t hum = -600 + 125 * ((humidity * 100) / 65535); /* 0.01 %RH */ #ifdef CONFIG_SHT4X_LIMIT_HUMIDITY /* Limit values of humidity, since values outside of 0-100 are invalid. */ if (hum < 0) { hum = 0; } else if (hum > 10000) { hum = 10000; } #endif // CONFIG_SHT4X_LIMIT_HUMIDITY return hum; } /**************************************************************************** * Name: has_time_passed * * Description: * Return true if curr >= start + secs_since_start * ****************************************************************************/ static bool has_time_passed(struct timespec curr, struct timespec start, unsigned int secs_since_start) { if ((long)((start.tv_sec + secs_since_start) - curr.tv_sec) == 0) { return start.tv_nsec <= curr.tv_nsec; } return (long)((start.tv_sec + secs_since_start) - curr.tv_sec) <= 0; } /**************************************************************************** * Name: sht4x_open * * Description: * This function is called whenever the SHT4X device is opened. * ****************************************************************************/ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int sht4x_open(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR struct sht4x_dev_s *priv = inode->i_private; int err; err = nxmutex_lock(&priv->devlock); if (err < 0) { return err; } /* Increment the count of open references on the driver */ priv->crefs++; DEBUGASSERT(priv->crefs > 0); nxmutex_unlock(&priv->devlock); return 0; } #endif /**************************************************************************** * Name: sht4x_close * * Description: * This routine is called when the SHT4X device is closed. * ****************************************************************************/ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int sht4x_close(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR struct sht4x_dev_s *priv = inode->i_private; int err; err = nxmutex_lock(&priv->devlock); if (err < 0) { return err; } /* Decrement the count of open references on the driver */ DEBUGASSERT(priv->crefs > 0); priv->crefs--; /* If the count has decremented to zero and the driver has been unlinked, * then free memory now. */ if (priv->crefs <= 0 && priv->unlinked) { nxmutex_destroy(&priv->devlock); kmm_free(priv); return 0; } nxmutex_unlock(&priv->devlock); return 0; } #endif /**************************************************************************** * Name: sht4x_read * * Description: * Character driver interface to sensor for debugging. * ****************************************************************************/ static ssize_t sht4x_read(FAR struct file *filep, FAR char *buffer, size_t buflen) { FAR struct inode *inode = filep->f_inode; FAR struct sht4x_dev_s *priv = inode->i_private; ssize_t length = 0; struct sht4x_raw_data_s raw_data; struct sht4x_conv_data_s data; int err; /* If file position is non-zero, then we're at the end of file. */ if (filep->f_pos > 0) { return 0; } /* Get exclusive access */ err = nxmutex_lock(&priv->devlock); if (err < 0) { return err; } #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS if (priv->unlinked) { /* Do not allow operations on unlinked sensors. This allows * sensor use on hot swappable I2C bus. */ nxmutex_unlock(&priv->devlock); return 0; } #endif err = sht4x_cmd(priv, g_precision_read[priv->precision], g_measurement_times[priv->precision], &raw_data.raw_temp, &raw_data.raw_hum); if (err < 0) { #ifdef CONFIG_SHT4X_DEBUG sht4x_dbg("Could not read device: %d\n", err); #endif // CONFIG_SHT4X_DEBUG nxmutex_unlock(&priv->devlock); return err; } /* Convert to proper units. */ data.temp = sht4x_calc_temp(raw_data.raw_temp); data.hum = sht4x_calc_hum(raw_data.raw_hum); length = snprintf(buffer, buflen, "%ld m" SHT4X_TEMP_UNIT ", %d %%RH\n", data.temp, data.hum / 100); if (length > buflen) { length = buflen; } filep->f_pos += length; nxmutex_unlock(&priv->devlock); return length; } /**************************************************************************** * Name: sht4x_write * * Description: * Not implemented. ****************************************************************************/ static ssize_t sht4x_write(FAR struct file *filep, FAR const char *buffer, size_t buflen) { return -ENOSYS; } /**************************************************************************** * Name: sht4x_ioctl ****************************************************************************/ static int sht4x_ioctl(FAR struct file *filep, int cmd, unsigned long arg) { FAR struct inode *inode = filep->f_inode; FAR struct sht4x_dev_s *priv = inode->i_private; int err; err = nxmutex_lock(&priv->devlock); if (err < 0) { return err; } #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS if (priv->unlinked) { /* Do not allow operations on unlinked sensors. This allows * sensor use on hot swappable I2C bus. */ nxmutex_unlock(&priv->devlock); return -ENODEV; } #endif switch (cmd) { case SNIOC_RESET: err = sht4x_reset(priv); break; case SNIOC_WHO_AM_I: { union sht4x_serialno_t serialno; err = sht4x_cmd(priv, SHT4X_READ_SERIAL, 10, &serialno.halves.msb, &serialno.halves.lsb); *((FAR uint32_t *)(arg)) = serialno.full; } break; case SNIOC_READ_RAW_DATA: err = sht4x_cmd(priv, g_precision_read[priv->precision], g_measurement_times[priv->precision], &((FAR struct sht4x_raw_data_s *)(arg))->raw_temp, &((FAR struct sht4x_raw_data_s *)(arg))->raw_hum); break; case SNIOC_MEASURE: case SNIOC_READ_CONVERT_DATA: { uint16_t raw_t; uint16_t raw_h; err = sht4x_cmd(priv, g_precision_read[priv->precision], g_measurement_times[priv->precision], &raw_t, &raw_h); ((FAR struct sht4x_conv_data_s *)(arg))->temp = sht4x_calc_temp(raw_t); ((FAR struct sht4x_conv_data_s *)(arg))->hum = sht4x_calc_hum(raw_h); } break; case SNIOC_HEAT: { struct timespec now; clock_systime_timespec(&now); /* Check if it has been one second since the last heat command. */ if (!has_time_passed(now, priv->last_heat, 1)) { err = -EAGAIN; /* Signal to try again in some time. */ break; } /* Caller must pass heater option in the temperature argument. */ uint16_t raw_t = ((FAR struct sht4x_conv_data_s *)(arg))->temp; uint16_t raw_h; err = sht4x_cmd(priv, g_heat_cmds[raw_t], g_heat_times[raw_t], &raw_t, &raw_h); ((FAR struct sht4x_conv_data_s *)(arg))->temp = sht4x_calc_temp(raw_t); ((FAR struct sht4x_conv_data_s *)(arg))->hum = sht4x_calc_hum(raw_h); clock_systime_timespec(&priv->last_heat); /* Update last heat time. */ } break; case SNIOC_CONFIGURE: /* Caller must pass precision option as argument. */ priv->precision = arg; #ifdef CONFIG_SHT4X_DEBUG sht4x_dbg("Precision set to %d\n", priv->precision); #endif // CONFIG_SHT4X_DEBUG break; default: err = -EINVAL; break; } nxmutex_unlock(&priv->devlock); return err; } /**************************************************************************** * Name: sht4x_unlink ****************************************************************************/ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int sht4x_unlink(FAR struct inode *inode) { FAR struct sht4x_dev_s *priv; int err; DEBUGASSERT(inode->i_private != NULL); priv = inode->i_private; err = nxmutex_lock(&priv->devlock); if (err < 0) { return err; } /* Are there open references to the driver data structure? */ if (priv->crefs <= 0) { nxmutex_destroy(&priv->devlock); kmm_free(priv); return 0; } /* No. Just mark the driver as unlinked and free the resources when * the last client closes their reference to the driver. */ priv->unlinked = true; nxmutex_unlock(&priv->devlock); return OK; } #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: sht4x_register * * Description: * Register the SHT4X character device as 'devpath' * * Input Parameters: * devpath - The full path to the driver to register. E.g., "/dev/temp0" * i2c - An instance of the I2C interface to use to communicate with * the SHT4X * addr - The I2C address of the SHT4X. The I2C address is one of 0x44, *0x45 and 0x46. * * Returned Value: * Zero (OK) on success; a negated errno value on failure. * ****************************************************************************/ int sht4x_register(FAR const char *devpath, FAR struct i2c_master_s *i2c, uint8_t addr) { FAR struct sht4x_dev_s *priv; int err; DEBUGASSERT(i2c != NULL); DEBUGASSERT(addr == 0x44 || addr == 0x45 || addr == 0x46); /* Initialize the device structure */ priv = kmm_zalloc(sizeof(struct sht4x_dev_s)); if (priv == NULL) { snerr("ERROR: Failed to allocate instance.\n"); return -ENOMEM; } priv->i2c = i2c; priv->addr = addr; priv->precision = SHT4X_PREC_HIGH; err = clock_systime_timespec(&priv->last_heat); if (err < 0) { snerr("ERROR: Failed to get timespec: %d\n", err); kmm_free(priv); return err; } /* Allow heat immediately after registration since in theory the sensor has * never had its heater activated yet. */ priv->last_heat.tv_sec -= 1; err = nxmutex_init(&priv->devlock); if (err < 0) { snerr("ERROR: Failed to register SHT4X driver: %d\n", err); kmm_free(priv); return err; } /* Register the character driver */ err = register_driver(devpath, &g_sht4xfops, 0666, priv); if (err < 0) { snerr("ERROR: Failed to register SHT4X driver: %d\n", err); nxmutex_destroy(&priv->devlock); kmm_free(priv); } return err; } #endif /* CONFIG_I2C && CONFIG_SENSORS_SHT4X */