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.
181 lines
5.8 KiB
181 lines
5.8 KiB
// -----------------------------------------------------------------------------
|
|
// SI7021 / HTU21D Sensor over I2C
|
|
// Copyright (C) 2017 by Xose Pérez <xose dot perez at gmail dot com>
|
|
// -----------------------------------------------------------------------------
|
|
|
|
#if SENSOR_SUPPORT && SI7021_SUPPORT
|
|
|
|
#pragma once
|
|
|
|
#include "Arduino.h"
|
|
#include "I2CSensor.h"
|
|
#if I2C_USE_BRZO
|
|
#include <brzo_i2c.h>
|
|
#else
|
|
#include <Wire.h>
|
|
#endif
|
|
|
|
#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
|
|
|
|
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;
|
|
_dirty = false;
|
|
|
|
// I2C auto-discover
|
|
unsigned char addresses[] = {0x40};
|
|
_address = _begin_i2c(_address, sizeof(addresses), addresses);
|
|
if (_address == 0) return;
|
|
|
|
// Check device
|
|
#if I2C_USE_BRZO
|
|
uint8_t buffer[2] = {0xFC, 0xC9};
|
|
brzo_i2c_start_transaction(_address, SI7021_SCL_FREQUENCY);
|
|
brzo_i2c_write(buffer, 2, false);
|
|
brzo_i2c_read(buffer, 1, false);
|
|
brzo_i2c_end_transaction();
|
|
_chip = buffer[0];
|
|
#else
|
|
Wire.beginTransmission(_address);
|
|
Wire.write(0xFC);
|
|
Wire.write(0xC9);
|
|
Wire.endTransmission();
|
|
Wire.requestFrom(_address, (unsigned char) 1);
|
|
_chip = Wire.read();
|
|
#endif
|
|
|
|
if ((_chip != SI7021_CHIP_SI7021) & (_chip != SI7021_CHIP_HTU21D)) {
|
|
i2cReleaseLock(_address);
|
|
_error = SENSOR_ERROR_UNKNOWN_ID;
|
|
} else {
|
|
_count = 2;
|
|
}
|
|
|
|
}
|
|
|
|
// Descriptive name of the sensor
|
|
String description() {
|
|
char buffer[25];
|
|
snprintf(buffer, sizeof(buffer), "%s @ I2C (0x%02X)", chipAsString().c_str(), _address);
|
|
return String(buffer);
|
|
}
|
|
|
|
// Type for slot # index
|
|
unsigned char type(unsigned char index) {
|
|
if (index < _count) {
|
|
_error = SENSOR_ERROR_OK;
|
|
if (index == 0) return MAGNITUDE_TEMPERATURE;
|
|
if (index == 1) return MAGNITUDE_HUMIDITY;
|
|
}
|
|
_error = SENSOR_ERROR_OUT_OF_RANGE;
|
|
return MAGNITUDE_NONE;
|
|
}
|
|
|
|
// Current value for slot # index
|
|
double value(unsigned char index) {
|
|
if (index < _count) {
|
|
_error = SENSOR_ERROR_OK;
|
|
double value;
|
|
if (index == 0) {
|
|
value = read(SI7021_CMD_TMP_NOHOLD);
|
|
value = (175.72 * value / 65536) - 46.85;
|
|
}
|
|
if (index == 1) {
|
|
value = read(SI7021_CMD_HUM_NOHOLD);
|
|
value = (125.0 * value / 65536) - 6;
|
|
value = constrain(value, 0, 100);
|
|
}
|
|
return value;
|
|
}
|
|
_error = SENSOR_ERROR_OUT_OF_RANGE;
|
|
return 0;
|
|
}
|
|
|
|
protected:
|
|
|
|
// ---------------------------------------------------------------------
|
|
// Protected
|
|
// ---------------------------------------------------------------------
|
|
|
|
unsigned int read(uint8_t command) {
|
|
|
|
unsigned char bytes = (command == 0xE0) ? 2 : 3;
|
|
|
|
#if I2C_USE_BRZO
|
|
uint8_t buffer[2] = {command, 0x00};
|
|
brzo_i2c_start_transaction(_address, SI7021_SCL_FREQUENCY);
|
|
brzo_i2c_write(buffer, 1, false);
|
|
#else
|
|
Wire.beginTransmission(_address);
|
|
Wire.write(command);
|
|
Wire.endTransmission();
|
|
#endif
|
|
|
|
// 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();
|
|
while (millis() - start < 50) delay(1);
|
|
|
|
#if I2C_USE_BRZO
|
|
brzo_i2c_read(buffer, 2, false);
|
|
brzo_i2c_end_transaction();
|
|
unsigned int msb = buffer[0];
|
|
unsigned int lsb = buffer[1];
|
|
#else
|
|
Wire.requestFrom(_address, bytes);
|
|
if (Wire.available() != bytes) {
|
|
_error = SENSOR_ERROR_CRC;
|
|
return 0;
|
|
}
|
|
unsigned int msb = Wire.read();
|
|
unsigned int lsb = Wire.read();
|
|
#endif
|
|
|
|
// Clear the last to bits of LSB to 00.
|
|
// According to datasheet LSB of RH is always xxxxxx10
|
|
lsb &= 0xFC;
|
|
|
|
unsigned int value = (msb << 8) | lsb;
|
|
|
|
_error = SENSOR_ERROR_OK;
|
|
return value;
|
|
|
|
}
|
|
|
|
String chipAsString() {
|
|
if (_chip == SI7021_CHIP_SI7021) return String("SI7021");
|
|
if (_chip == SI7021_CHIP_HTU21D) return String("HTU21D");
|
|
return String("Unknown");
|
|
}
|
|
|
|
unsigned char _chip;
|
|
|
|
};
|
|
|
|
#endif // SENSOR_SUPPORT && SI7021_SUPPORT
|