// -----------------------------------------------------------------------------
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// SHT3X Sensor over I2C (Wemos)
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// Copyright (C) 2017 by Xose Pérez <xose dot perez at gmail dot com>
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// -----------------------------------------------------------------------------
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#if SENSOR_SUPPORT && SHT3X_I2C_SUPPORT
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#pragma once
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#include "Arduino.h"
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#include "I2CSensor.h"
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#if I2C_USE_BRZO
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#include <brzo_i2c.h>
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#else
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#include <Wire.h>
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#endif
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class SHT3XI2CSensor : public I2CSensor {
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public:
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// ---------------------------------------------------------------------
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// Public
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// ---------------------------------------------------------------------
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SHT3XI2CSensor(): I2CSensor() {
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_sensor_id = SENSOR_SHT3X_I2C_ID;
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_count = 2;
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}
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// ---------------------------------------------------------------------
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// Sensor API
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// ---------------------------------------------------------------------
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// Initialization method, must be idempotent
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void begin() {
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if (!_dirty) return;
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_dirty = false;
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// I2C auto-discover
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unsigned char addresses[] = {0x45};
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_address = _begin_i2c(_address, sizeof(addresses), addresses);
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if (_address == 0) return;
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}
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// Descriptive name of the sensor
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String description() {
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char buffer[25];
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snprintf(buffer, sizeof(buffer), "SHT3X @ I2C (0x%02X)", _address);
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return String(buffer);
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}
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// Type for slot # index
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unsigned char type(unsigned char index) {
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if (index < _count) {
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_error = SENSOR_ERROR_OK;
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if (index == 0) return MAGNITUDE_TEMPERATURE;
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if (index == 1) return MAGNITUDE_HUMIDITY;
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}
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_error = SENSOR_ERROR_OUT_OF_RANGE;
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return MAGNITUDE_NONE;
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}
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// Pre-read hook (usually to populate registers with up-to-date data)
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void pre() {
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unsigned char buffer[6];
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#if I2C_USE_BRZO
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buffer[0] = 0x2C;
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buffer[1] = 0x06;
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brzo_i2c_start_transaction(_address, I2C_SCL_FREQUENCY);
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brzo_i2c_write(buffer, 2, false);
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#else
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Wire.beginTransmission(_address);
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Wire.write(0x2C);
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Wire.write(0x06);
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if (Wire.endTransmission() != 0) {
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_error = SENSOR_ERROR_TIMEOUT;
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return;
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}
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#endif
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delay(500);
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#if I2C_USE_BRZO
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brzo_i2c_read(buffer, 6, false);
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brzo_i2c_end_transaction();
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#else
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Wire.requestFrom(_address, (unsigned char) 6);
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for (int i=0; i<6; i++) buffer[i] = Wire.read();
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delay(50);
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if (Wire.available() != 0) {
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_error = SENSOR_ERROR_CRC;
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return;
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}
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#endif
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// cTemp msb, cTemp lsb, cTemp crc, humidity msb, humidity lsb, humidity crc
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_temperature = ((((buffer[0] * 256.0) + buffer[1]) * 175) / 65535.0) - 45;
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_humidity = ((((buffer[3] * 256.0) + buffer[4]) * 100) / 65535.0);
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}
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// Current value for slot # index
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double value(unsigned char index) {
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_error = SENSOR_ERROR_OK;
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if (index == 0) return _temperature;
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if (index == 1) return _humidity;
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_error = SENSOR_ERROR_OUT_OF_RANGE;
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return 0;
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}
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protected:
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double _temperature = 0;
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unsigned char _humidity = 0;
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};
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#endif // SENSOR_SUPPORT && SHT3X_I2C_SUPPORT
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