1 /* 2 * Copyright (c) 2021 Leonard Pollak 3 * 4 * SPDX-License-Identifier: Apache-2.0 5 */ 6 7 #ifndef ZEPHYR_DRIVERS_SENSOR_SHT4X_SHT4X_H_ 8 #define ZEPHYR_DRIVERS_SENSOR_SHT4X_SHT4X_H_ 9 10 #include <zephyr/device.h> 11 12 #define SHT4X_CMD_READ_SERIAL 0x89 13 #define SHT4X_CMD_RESET 0x94 14 15 #define SHT4X_RESET_WAIT_MS 1 16 17 #define SHT4X_HEATER_POWER_IDX_MAX 3 18 #define SHT4X_HEATER_DURATION_IDX_MAX 2 19 20 /* 21 * CRC parameters were taken from the 22 * "Checksum Calculation" section of the datasheet. 23 */ 24 #define SHT4X_CRC_POLY 0x31 25 #define SHT4X_CRC_INIT 0xFF 26 27 struct sht4x_config { 28 struct i2c_dt_spec bus; 29 uint8_t repeatability; 30 }; 31 32 struct sht4x_data { 33 uint16_t t_sample; 34 uint16_t rh_sample; 35 uint8_t heater_power; 36 uint8_t heater_duration; 37 }; 38 39 static const uint8_t measure_cmd[3] = { 40 0xE0, 0xF6, 0xFD 41 }; 42 43 static const uint16_t measure_wait_us[3] = { 44 1700, 4500, 8200 45 }; 46 47 /* 48 * heater specifics 49 * 50 * power: 51 * High power heater pulse -> ~200 mW @3.3V 52 * Medium power heater pulse -> ~110 mW @3.3V 53 * Low power heater pulse -> ~20 mW @3.3V 54 * 55 * duration: 56 * Long heater pulse -> 1.1s 57 * Short heater pulse -> 0.11s 58 */ 59 60 static const int8_t heater_cmd[SHT4X_HEATER_POWER_IDX_MAX][SHT4X_HEATER_DURATION_IDX_MAX] = { 61 { 0x39, 0x32 }, 62 { 0x2F, 0x24 }, 63 { 0x1E, 0x15 } 64 }; 65 66 static const uint32_t heater_wait_ms[SHT4X_HEATER_DURATION_IDX_MAX] = { 67 1000, 100 68 }; 69 70 #endif /* ZEPHYR_DRIVERS_SENSOR_SHT4X_SHT4X_H_ */ 71
