114 lines
3.1 KiB
C++
114 lines
3.1 KiB
C++
#include "DFRobot_SHT20.h"
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void DFRobot_SHT20::initSHT20(TwoWire &wirePort)
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{
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i2cPort = &wirePort;
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i2cPort->begin();
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}
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uint16_t DFRobot_SHT20::readValue(byte cmd)
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{
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i2cPort->beginTransmission(SLAVE_ADDRESS);
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i2cPort->write(cmd);
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i2cPort->endTransmission();
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byte toRead;
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byte counter;
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for(counter = 0, toRead = 0 ; counter < MAX_COUNTER && toRead != 3; counter++){
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delay(DELAY_INTERVAL);
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toRead = i2cPort->requestFrom(SLAVE_ADDRESS, 3);
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}
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if(counter == MAX_COUNTER){
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return (ERROR_I2C_TIMEOUT);
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}
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byte msb, lsb, checksum;
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msb = i2cPort->read();
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lsb = i2cPort->read();
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checksum = i2cPort->read();
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uint16_t rawValue = ((uint16_t) msb << 8) | (uint16_t) lsb;
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if(checkCRC(rawValue, checksum) != 0){
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return (ERROR_BAD_CRC);
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}
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return rawValue & 0xFFFC;
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}
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float DFRobot_SHT20::readHumidity(void)
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{
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uint16_t rawHumidity = readValue(TRIGGER_HUMD_MEASURE_NOHOLD);
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if(rawHumidity == ERROR_I2C_TIMEOUT || rawHumidity == ERROR_BAD_CRC){
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return(rawHumidity);
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}
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float tempRH = rawHumidity * (125.0 / 65536.0);
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float rh = tempRH - 6.0;
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return (rh);
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}
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float DFRobot_SHT20::readTemperature(void)
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{
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uint16_t rawTemperature = readValue(TRIGGER_TEMP_MEASURE_NOHOLD);
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if(rawTemperature == ERROR_I2C_TIMEOUT || rawTemperature == ERROR_BAD_CRC){
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return(rawTemperature);
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}
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float tempTemperature = rawTemperature * (175.72 / 65536.0);
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float realTemperature = tempTemperature - 46.85;
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return (realTemperature);
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}
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void DFRobot_SHT20::setResolution(byte resolution)
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{
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byte userRegister = readUserRegister();
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userRegister &= B01111110;
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resolution &= B10000001;
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userRegister |= resolution;
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writeUserRegister(userRegister);
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}
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byte DFRobot_SHT20::readUserRegister(void)
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{
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byte userRegister;
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i2cPort->beginTransmission(SLAVE_ADDRESS);
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i2cPort->write(READ_USER_REG);
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i2cPort->endTransmission();
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i2cPort->requestFrom(SLAVE_ADDRESS, 1);
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userRegister = i2cPort->read();
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return (userRegister);
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}
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void DFRobot_SHT20::writeUserRegister(byte val)
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{
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i2cPort->beginTransmission(SLAVE_ADDRESS);
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i2cPort->write(WRITE_USER_REG);
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i2cPort->write(val);
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i2cPort->endTransmission();
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}
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byte DFRobot_SHT20::checkCRC(uint16_t message_from_sensor, uint8_t check_value_from_sensor)
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{
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uint32_t remainder = (uint32_t)message_from_sensor << 8;
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remainder |= check_value_from_sensor;
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uint32_t divsor = (uint32_t)SHIFTED_DIVISOR;
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for(int i = 0 ; i < 16 ; i++){
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if(remainder & (uint32_t)1 << (23 - i)){
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remainder ^= divsor;
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}
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divsor >>= 1;
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}
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return (byte)remainder;
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}
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void DFRobot_SHT20::showReslut(const char *prefix, int val)
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{
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Serial.print(prefix);
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if(val){
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Serial.println("yes");
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}else{
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Serial.println("no");
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}
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}
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void DFRobot_SHT20::checkSHT20(void)
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{
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byte reg = readUserRegister();
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showReslut("End of battery: ", reg & USER_REGISTER_END_OF_BATTERY);
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showReslut("Heater enabled: ", reg & USER_REGISTER_HEATER_ENABLED);
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showReslut("Disable OTP reload: ", reg & USER_REGISTER_DISABLE_OTP_RELOAD);
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} |