Ksenia Kondrashova / HYT

Lib for HYT temp & humidity sensor

Dependents:   HYT_example Temp_&_RH_at_TFT-demo Temp_&_RH_at_TFT_with_touchscreen Temp_&_RH_at_TFT_with_touchscreen-ENG ... more

Fork of HYT by Ksenia Kondrashova

This is a simple library for the HYT-271, HYT-221 and HYT-939 humidity and temperature sensors by IST-AG company. The difference between HYT sensors is only a package.

/media/uploads/Ksenia/3-in-1-small.png

General information:

  • High precision: +/-1.8%RH and 0.2°C
  • Temperature range: -40°C to +125°C
  • Low drift : less than 0,5% RH / year
  • Power consumption: 22 µA during operation
  • Fully calibrated and compensated humidity and temperature signal
  • Digital I2C interface (14 bit values)

Product Page: http://www.ist-ag.com/eh/ist-ag/en/home.nsf/contentview/~humidity-modules

Remember to use pull-up resisrors:

/media/uploads/Ksenia/freshpaint-20-2016.09.16-10.37.03.png

You can also find Hello Word program sending data from sensor to PC via serial interface: https://developer.mbed.org/users/Ksenia/code/HYT_example/

Library doesn't contain command mode instructions. There are only functions for polling the HYT sensor with default i2c address

HYT.cpp@0:cb02bfe8cf44, 2016-09-14 (annotated)

Committer:
Ksenia
Date:
Wed Sep 14 15:22:42 2016 +0000
Revision:
0:cb02bfe8cf44
Initial commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Ksenia 0:cb02bfe8cf44 1 #include "HYT.h"
Ksenia 0:cb02bfe8cf44 2 #include "mbed.h"
Ksenia 0:cb02bfe8cf44 3
Ksenia 0:cb02bfe8cf44 4 HYT::HYT(PinName sda, PinName scl) : _i2c(sda, scl)
Ksenia 0:cb02bfe8cf44 5 {
Ksenia 0:cb02bfe8cf44 6 }
Ksenia 0:cb02bfe8cf44 7
Ksenia 0:cb02bfe8cf44 8 /*************************************************************************************************************************/
Ksenia 0:cb02bfe8cf44 9 void HYT::MRCommand(void)
Ksenia 0:cb02bfe8cf44 10 {
Ksenia 0:cb02bfe8cf44 11 _i2c.write(HYT_ADDR, 0, 0);
Ksenia 0:cb02bfe8cf44 12 }
Ksenia 0:cb02bfe8cf44 13
Ksenia 0:cb02bfe8cf44 14
Ksenia 0:cb02bfe8cf44 15 /*************************************************************************************************************************/
Ksenia 0:cb02bfe8cf44 16 int HYT::DFCommand(void)
Ksenia 0:cb02bfe8cf44 17 {
Ksenia 0:cb02bfe8cf44 18 char dataI2C[4];
Ksenia 0:cb02bfe8cf44 19 int stateBit;
Ksenia 0:cb02bfe8cf44 20 int humidityRaw;
Ksenia 0:cb02bfe8cf44 21 int temperatureRaw;
Ksenia 0:cb02bfe8cf44 22
Ksenia 0:cb02bfe8cf44 23 _i2c.read(HYT_ADDR, dataI2C, 4);
Ksenia 0:cb02bfe8cf44 24
Ksenia 0:cb02bfe8cf44 25 stateBit = (dataI2C[0] & 0x40) >> 6;
Ksenia 0:cb02bfe8cf44 26 if (stateBit == 0) {
Ksenia 0:cb02bfe8cf44 27 humidityRaw = ((dataI2C[0] & 0x3F) << 8) | dataI2C[1];
Ksenia 0:cb02bfe8cf44 28 temperatureRaw = ((dataI2C[2] << 8) | dataI2C[3]) >> 2;
Ksenia 0:cb02bfe8cf44 29 if (temperatureRaw < 0x3FFF && humidityRaw < 0x3FFF) {
Ksenia 0:cb02bfe8cf44 30 temperature = ((float)(temperatureRaw) * 165.0f / 16383.0f) - 40.0f;
Ksenia 0:cb02bfe8cf44 31 humidity = (float)humidityRaw * 100.0f / 16383.0f;
Ksenia 0:cb02bfe8cf44 32 } else {
Ksenia 0:cb02bfe8cf44 33 // sensor returns wrong data (1111...11)
Ksenia 0:cb02bfe8cf44 34 return -1;
Ksenia 0:cb02bfe8cf44 35 }
Ksenia 0:cb02bfe8cf44 36 } else {
Ksenia 0:cb02bfe8cf44 37 // no new value received from sensor
Ksenia 0:cb02bfe8cf44 38 return 0;
Ksenia 0:cb02bfe8cf44 39 }
Ksenia 0:cb02bfe8cf44 40
Ksenia 0:cb02bfe8cf44 41 return 0;
Ksenia 0:cb02bfe8cf44 42 }