You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
168 lines
5.0 KiB
168 lines
5.0 KiB
// -----------------------------------------------------------------------------
|
|
// SI7021 / HTU21D Sensor over I2C
|
|
// Copyright (C) 2017-2018 by Xose Pérez <xose dot perez at gmail dot com>
|
|
// -----------------------------------------------------------------------------
|
|
|
|
#if SENSOR_SUPPORT && SI7021_SUPPORT
|
|
|
|
#pragma once
|
|
|
|
#include "Arduino.h"
|
|
#include "I2CSensor.h"
|
|
|
|
#define SI7021_SCL_FREQUENCY 200
|
|
|
|
#define SI7021_CHIP_SI7021 0x15
|
|
#define SI7021_CHIP_HTU21D 0x32
|
|
|
|
#define SI7021_CMD_TMP_HOLD 0xE3
|
|
#define SI7021_CMD_HUM_HOLD 0xE5
|
|
#define SI7021_CMD_TMP_NOHOLD 0xF3
|
|
#define SI7021_CMD_HUM_NOHOLD 0xF5
|
|
|
|
PROGMEM const char si7021_chip_si7021_name[] = "SI7021";
|
|
PROGMEM const char si7021_chip_htu21d_name[] = "HTU21D";
|
|
|
|
class SI7021Sensor : public I2CSensor {
|
|
|
|
public:
|
|
|
|
// ---------------------------------------------------------------------
|
|
// Public
|
|
// ---------------------------------------------------------------------
|
|
|
|
SI7021Sensor(): I2CSensor() {
|
|
_sensor_id = SENSOR_SI7021_ID;
|
|
}
|
|
|
|
// ---------------------------------------------------------------------
|
|
// Sensor API
|
|
// ---------------------------------------------------------------------
|
|
|
|
// Initialization method, must be idempotent
|
|
void begin() {
|
|
if (!_dirty) return;
|
|
_init();
|
|
_dirty = !_ready;
|
|
}
|
|
|
|
// Descriptive name of the sensor
|
|
String description() {
|
|
char name[10];
|
|
strncpy_P(name,
|
|
_chip == SI7021_CHIP_SI7021 ?
|
|
si7021_chip_si7021_name :
|
|
si7021_chip_htu21d_name,
|
|
sizeof(name)
|
|
);
|
|
char buffer[25];
|
|
snprintf(buffer, sizeof(buffer), "%s @ I2C (0x%02X)", name, _address);
|
|
return String(buffer);
|
|
}
|
|
|
|
// Descriptive name of the slot # index
|
|
String slot(unsigned char index) {
|
|
return description();
|
|
};
|
|
|
|
// Type for slot # index
|
|
unsigned char type(unsigned char index) {
|
|
if (index == 0) return MAGNITUDE_TEMPERATURE;
|
|
if (index == 1) return MAGNITUDE_HUMIDITY;
|
|
return MAGNITUDE_NONE;
|
|
}
|
|
|
|
// Pre-read hook (usually to populate registers with up-to-date data)
|
|
void pre() {
|
|
|
|
_error = SENSOR_ERROR_UNKNOWN_ID;
|
|
if (_chip == 0) return;
|
|
_error = SENSOR_ERROR_OK;
|
|
|
|
double value;
|
|
|
|
value = _read(SI7021_CMD_TMP_NOHOLD);
|
|
if (_error != SENSOR_ERROR_OK) return;
|
|
_temperature = (175.72 * value / 65536) - 46.85;
|
|
|
|
value = _read(SI7021_CMD_HUM_NOHOLD);
|
|
if (_error != SENSOR_ERROR_OK) return;
|
|
value = (125.0 * value / 65536) - 6;
|
|
_humidity = constrain(value, 0, 100);
|
|
|
|
}
|
|
|
|
// Current value for slot # index
|
|
double value(unsigned char index) {
|
|
if (index == 0) return _temperature;
|
|
if (index == 1) return _humidity;
|
|
return 0;
|
|
}
|
|
|
|
protected:
|
|
|
|
// ---------------------------------------------------------------------
|
|
// Protected
|
|
// ---------------------------------------------------------------------
|
|
|
|
void _init() {
|
|
|
|
// I2C auto-discover
|
|
unsigned char addresses[] = {0x40};
|
|
_address = _begin_i2c(_address, sizeof(addresses), addresses);
|
|
if (_address == 0) return;
|
|
|
|
// Check device
|
|
i2c_write_uint8(_address, 0xFC, 0xC9);
|
|
_chip = i2c_read_uint8(_address);
|
|
|
|
if ((_chip != SI7021_CHIP_SI7021) & (_chip != SI7021_CHIP_HTU21D)) {
|
|
|
|
_count = 0;
|
|
i2cReleaseLock(_address);
|
|
_previous_address = 0;
|
|
_error = SENSOR_ERROR_UNKNOWN_ID;
|
|
|
|
// Setting _address to 0 forces auto-discover
|
|
// This might be necessary at this stage if there is a
|
|
// different sensor in the hardcoded address
|
|
_address = 0;
|
|
|
|
} else {
|
|
_count = 2;
|
|
}
|
|
|
|
_ready = true;
|
|
|
|
}
|
|
|
|
unsigned int _read(uint8_t command) {
|
|
|
|
// Request measurement
|
|
i2c_write_uint8(_address, command);
|
|
|
|
// When not using clock stretching (*_NOHOLD commands) delay here
|
|
// is needed to wait for the measurement.
|
|
// According to datasheet the max. conversion time is ~22ms
|
|
unsigned long start = millis();
|
|
nice_delay(50);
|
|
|
|
// Clear the last to bits of LSB to 00.
|
|
// According to datasheet LSB of RH is always xxxxxx10
|
|
unsigned int value = i2c_read_uint16(_address) & 0xFFFC;
|
|
|
|
// We should be checking there are no pending bytes in the buffer
|
|
// and raise a CRC error if there are
|
|
_error = SENSOR_ERROR_OK;
|
|
|
|
return value;
|
|
|
|
}
|
|
|
|
unsigned char _chip;
|
|
double _temperature = 0;
|
|
double _humidity = 0;
|
|
|
|
};
|
|
|
|
#endif // SENSOR_SUPPORT && SI7021_SUPPORT
|