mirror of
https://github.com/RobTillaart/Arduino.git
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368 lines
6.7 KiB
C++
368 lines
6.7 KiB
C++
//
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// FILE: SHT85.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.2.0
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// DATE: 2021-02-10
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// PURPOSE: Arduino library for the SHT85 temperature and humidity sensor
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// https://nl.rs-online.com/web/p/temperature-humidity-sensor-ics/1826530
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// URL: https://github.com/RobTillaart/SHT85
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//
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// HISTORY:
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// 0.1.0 2021-02-10 initial version
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// 0.1.1 2021-03-13 initial release
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// 0.1.2 2021-05-27 fix Arduino-lint
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// 0.1.3 2021-08-06 expose raw data from sensor
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// 0.1.4 2021-08-24 prevent heater to switch on too fast.
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// update readme
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// 0.2.0 2021-08-24 split off base class
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// create derived classes SHT85, 30, 31, 35
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#include "SHT85.h"
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// SUPPORTED COMMANDS - single shot mode only
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#define SHT_READ_STATUS 0xF32D
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#define SHT_CLEAR_STATUS 0x3041
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#define SHT_SOFT_RESET 0x30A2
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#define SHT_HARD_RESET 0x0006
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#define SHT_MEASUREMENT_FAST 0x2416 // page 10 datasheet
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#define SHT_MEASUREMENT_SLOW 0x2400 // no clock stretching
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#define SHT_HEAT_ON 0x306D
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#define SHT_HEAT_OFF 0x3066
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#define SHT_HEATER_TIMEOUT 180000UL // milliseconds
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SHT::SHT()
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{
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_address = 0;
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_lastRead = 0;
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_rawTemperature = 0;
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_rawHumidity = 0;
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_heatTimeout = 0;
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_heaterStart = 0;
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_heaterStop = 0;
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_heaterOn = false;
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_error = SHT_OK;
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_type = 0;
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}
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#if defined(ESP8266) || defined(ESP32)
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bool SHT::begin(const uint8_t address, const uint8_t dataPin, const uint8_t clockPin)
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{
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if ((address != 0x44) && (address != 0x45))
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{
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return false;
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}
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_address = address;
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_wire = &Wire;
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if ((dataPin < 255) && (clockPin < 255))
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{
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_wire->begin(dataPin, clockPin);
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} else {
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_wire->begin();
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}
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return reset();
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}
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#endif
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bool SHT::begin(const uint8_t address, TwoWire *wire)
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{
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if ((address != 0x44) && (address != 0x45))
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{
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return false;
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}
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_address = address;
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_wire = wire;
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_wire->begin();
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return reset();
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}
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bool SHT::read(bool fast)
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{
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if (writeCmd(fast ? SHT_MEASUREMENT_FAST : SHT_MEASUREMENT_SLOW) == false)
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{
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return false;
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}
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delay(fast ? 4 : 15); // table 4 datasheet
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return readData(fast);
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}
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bool SHT::isConnected()
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{
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_wire->beginTransmission(_address);
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int rv = _wire->endTransmission();
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if (rv != 0) _error = SHT_ERR_NOT_CONNECT;
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return (rv == 0);
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}
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#ifdef doc
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// bit - description
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// ==================
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// 15 Alert pending status
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// '0': no pending alerts
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// '1': at least one pending alert - default
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// 14 Reserved ‘0’
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// 13 Heater status
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// '0’ : Heater OFF - default
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// '1’ : Heater ON
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// 12 Reserved '0’
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// 11 Humidity tracking alert
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// '0’ : no alert - default
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// '1’ : alert
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// 10 Temp tracking alert
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// '0’ : no alert - default
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// '1’ : alert
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// 9:5 Reserved '00000’
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// 4 System reset detected
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// '0': no reset since last ‘clear status register’ command
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// '1': reset detected (hard or soft reset command or supply fail) - default
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// 3:2 Reserved ‘00’
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// 1 Command status
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// '0': last command executed successfully
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// '1': last command not processed. Invalid or failed checksum
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// 0 Write data checksum status
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// '0': checksum of last write correct
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// '1': checksum of last write transfer failed
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#endif
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uint16_t SHT::readStatus()
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{
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uint8_t status[3] = { 0, 0, 0 };
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// page 13 datasheet
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if (writeCmd(SHT_READ_STATUS) == false)
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{
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return 0xFFFF;
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}
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// 16 bit status + CRC
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if (readBytes(3, (uint8_t*) &status[0]) == false)
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{
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return 0xFFFF;
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}
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if (status[2] != crc8(status, 2))
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{
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_error = SHT_ERR_CRC_STATUS;
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return 0xFFFF;
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}
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return (uint16_t) (status[0] << 8) + status[1];
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}
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bool SHT::reset(bool hard)
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{
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bool b = writeCmd(hard ? SHT_HARD_RESET : SHT_SOFT_RESET);
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if (b == false)
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{
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return false;
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}
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delay(1); // table 4 datasheet
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return true;
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}
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void SHT::setHeatTimeout(uint8_t seconds)
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{
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_heatTimeout = seconds;
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if (_heatTimeout > 180) _heatTimeout = 180;
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}
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bool SHT::heatOn()
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{
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if (isHeaterOn()) return true;
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if ((_heaterStop > 0) && (millis() - _heaterStop < SHT_HEATER_TIMEOUT))
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{
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_error = SHT_ERR_HEATER_COOLDOWN;
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return false;
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}
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if (writeCmd(SHT_HEAT_ON) == false)
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{
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_error = SHT_ERR_HEATER_ON;
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return false;
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}
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_heaterStart = millis();
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_heaterOn = true;
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return true;
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}
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bool SHT::heatOff()
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{
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// always switch off the heater - ignore _heaterOn flag.
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if (writeCmd(SHT_HEAT_OFF) == false)
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{
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_error = SHT_ERR_HEATER_OFF; // can be serious!
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return false;
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}
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_heaterStop = millis();
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_heaterOn = false;
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return true;
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}
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bool SHT::isHeaterOn()
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{
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if (_heaterOn == false)
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{
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return false;
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}
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// did not exceed time out
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if (millis() - _heaterStart < (_heatTimeout * 1000UL))
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{
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return true;
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}
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heatOff();
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return false;
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}
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bool SHT::requestData()
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{
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if (writeCmd(SHT_MEASUREMENT_SLOW) == false)
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{
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return false;
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}
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_lastRequest = millis();
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return true;
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}
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bool SHT::dataReady()
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{
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return ((millis() - _lastRequest) > 15); // TODO MAGIC NR
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}
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bool SHT::readData(bool fast)
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{
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uint8_t buffer[6];
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if (readBytes(6, (uint8_t*) &buffer[0]) == false)
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{
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return false;
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}
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if (!fast)
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{
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if (buffer[2] != crc8(buffer, 2))
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{
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_error = SHT_ERR_CRC_TEMP;
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return false;
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}
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if (buffer[5] != crc8(buffer + 3, 2))
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{
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_error = SHT_ERR_CRC_HUM;
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return false;
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}
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}
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_rawTemperature = (buffer[0] << 8) + buffer[1];
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_rawHumidity = (buffer[3] << 8) + buffer[4];
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_lastRead = millis();
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return true;
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}
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int SHT::getError()
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{
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int rv = _error;
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_error = SHT_OK;
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return rv;
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}
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//////////////////////////////////////////////////////////
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uint8_t SHT::crc8(const uint8_t *data, uint8_t len)
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{
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// CRC-8 formula from page 14 of SHT spec pdf
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const uint8_t POLY(0x31);
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uint8_t crc(0xFF);
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for (uint8_t j = len; j; --j)
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{
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crc ^= *data++;
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for (uint8_t i = 8; i; --i)
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{
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crc = (crc & 0x80) ? (crc << 1) ^ POLY : (crc << 1);
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}
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}
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return crc;
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}
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bool SHT::writeCmd(uint16_t cmd)
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{
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_wire->beginTransmission(_address);
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_wire->write(cmd >> 8 );
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_wire->write(cmd & 0xFF);
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if (_wire->endTransmission() != 0)
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{
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_error = SHT_ERR_WRITECMD;
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return false;
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}
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return true;
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}
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bool SHT::readBytes(uint8_t n, uint8_t *val)
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{
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int rv = _wire->requestFrom(_address, (uint8_t) n);
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if (rv == n)
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{
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for (uint8_t i = 0; i < n; i++)
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{
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val[i] = _wire->read();
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}
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return true;
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}
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_error = SHT_ERR_READBYTES;
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return false;
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}
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////////////////////////////////////////////////////////
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//
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// DERIVED
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//
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SHT30::SHT30()
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{
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_type = 30;
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};
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SHT31::SHT31()
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{
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_type = 31;
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};
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SHT35::SHT35()
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{
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_type = 35;
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};
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SHT85::SHT85()
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{
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_type = 85;
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};
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// -- END OF FILE --
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