mirror of
https://github.com/1991Patrick/I2C_SHT2x.git
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257 lines
9.9 KiB
C
257 lines
9.9 KiB
C
/*!
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* \file I2C_SHT2x.c
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* \author Patrick Taling (not the original author from the original code of SENSIRION AG)
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* \date 31/03/2017
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* \version 1.0
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*
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* \brief Simple I2C SHT2x library to measure relative humidity and temperature and write it to an I2C LCD with the ATxmega256a3u.
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*
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* \details The file I2C_SHT2x.c is the library for the SHT2x humidity and temperature sensor
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*
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* The library needs the i2c library from w.e.dolman (<a href="mailto:w.e.dolman@hva.nl">w.e.dolman@hva.nl</a>)
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* For i2c.c use code 21.8 from "de taal C en de Xmega tweede druk" http://dolman-wim.nl/xmega/book/index.php
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* For i2c.h use code 21.9 from "de taal C en de Xmega tweede druk" http://dolman-wim.nl/xmega/book/index.php
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*
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* The libraby needs some parts of the the SHT2x library from SENIRION from https://www.sensirion.com/en/products/humidity-sensors/humidity-temperature-sensor-sht2x-digital-i2c-accurate/
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* The libraby can be download from: https://www.sensirion.com/en/products/all-documents-of-sensirions-humidity-sensors-for-download/
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* Go to SHT2x/ Sample Code SHT21 and download the zip file Sensirion_Humidity_Sensors_SHT21_Sample_Code_C-file
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*
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* \note the following files aren't fully used. Most parts are used in other .c of .h files or disabled.
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* DisplayDip204.C, DisplayDip204.h,
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* I2C_HAL.c, I2C_HAL.h,
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* System.c, System.h and
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* io70f3740.h.
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* \note for the use of two SHT2X you should use different IOs for SDA or additional hardware such as I2C multiplexer.
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* The adress of the SHT2x can’t be changed.
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*
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*
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* \ORIGINAL AUTHOR INFORMATION
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* ==============================================================================
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* S E N S I R I O N AG, Laubisruetistr. 50, CH-8712 Staefa, Switzerland
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* ==============================================================================
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* Project : SHT2x Sample Code (V1.2)
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* File : SHT2x.c
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* Author : MST
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* Controller: NEC V850/SG3 (uPD70F3740)
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* Compiler : IAR compiler for V850 (3.50A)
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* Brief : Sensor layer. Functions for sensor access
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* ==============================================================================
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*
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*
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* \verbatim
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#include <I2C_SHT2x.h>
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#include <i2c.h>
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#include <Typedefs.h>
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\endverbatim
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* \par
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*
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* \note An AVR-project can use multiple I2C's. One shoud take care that
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* in different source files there are no multiple I2C
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* definitions for the same I2C.
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*/
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#define F_CPU 2000000UL
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#include "I2C_SHT2x.h"
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#include "i2c.h"
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#include "Typedefs.h"
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#include <util/delay.h>
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#include <assert.h>
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#include <math.h>
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//==============================================================================
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uint8_t i2c_SHT2x_CheckCrc(uint8_t data[], uint8_t nbrOfBytes, uint8_t checksum)
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//==============================================================================
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{
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uint8_t crc = 0;
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uint8_t byteCtr;
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//calculates 8-Bit checksum with given polynomial
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for (byteCtr = 0; byteCtr < nbrOfBytes; ++byteCtr)
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{ crc ^= (data[byteCtr]);
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for (uint8_t bit = 8; bit > 0; --bit)
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{ if (crc & 0x80) {crc = (crc << 1) ^ POLYNOMIAL;}
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else crc = (crc << 1);
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}
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}
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if (crc != checksum) return CHECKSUM_ERROR;
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else return 0;
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}
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//===========================================================================
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uint8_t i2c_SHT2x_ReadUserRegister(uint8_t *pRegisterValue)
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//===========================================================================
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{
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uint8_t checksum;
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uint8_t error=0;
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 0);
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error |= i2c_write(&TWIE, USER_REG_R);
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i2c_stop(&TWIE);
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 1);
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*pRegisterValue = i2c_read(&TWIE, I2C_ACK);
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checksum=i2c_read(&TWIE, I2C_NACK);
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error |= i2c_SHT2x_CheckCrc (pRegisterValue,1,checksum);
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i2c_stop(&TWIE);
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return error;
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}
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//===========================================================================
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uint8_t i2c_SHT2x_WriteUserRegister(uint8_t *pRegisterValue)
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//===========================================================================
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{
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uint8_t error=0;
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_delay_ms(2000);
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 0);
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error |= i2c_write(&TWIE, USER_REG_W);
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error |= i2c_write(&TWIE, *pRegisterValue);
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i2c_stop(&TWIE);
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return error;
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}
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//===========================================================================
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uint8_t i2c_SHT2x_MeasureHM(etSHT2xMeasureType eSHT2xMeasureType, nt16 *pMeasurand)
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//===========================================================================
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{
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uint8_t checksum;
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uint8_t data[2];
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uint8_t error=0;
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//-- write I2C sensor address and command --
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 0);
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switch(eSHT2xMeasureType)
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{ case HUMIDITY: error |= i2c_write(&TWIE, TRIG_RH_MEASUREMENT_HM); break;
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case TEMP: error |= i2c_write(&TWIE, TRIG_T_MEASUREMENT_HM); break;
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default: assert(0);
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}
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i2c_stop(&TWIE);
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//-- wait until hold master is released --
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 1);
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//-- read two data bytes and one checksum byte --
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pMeasurand->s16.u8H = data[0] = i2c_read(&TWIE, I2C_ACK);
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pMeasurand->s16.u8L = data[1] = i2c_read(&TWIE, I2C_ACK);
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checksum= i2c_read(&TWIE, I2C_NACK);
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//-- verify checksum --
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error |= i2c_SHT2x_CheckCrc (data,2,checksum);
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i2c_stop(&TWIE);
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return error;
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}
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//===========================================================================
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uint8_t i2c_SHT2x_MeasurePoll(etSHT2xMeasureType eSHT2xMeasureType, nt16 *pMeasurand)
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//--- Disabled due to error in TEMP ---
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//--- measuring TEMP doesn't work after the do while loop ---
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//===========================================================================
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{
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uint8_t checksum;
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uint8_t data[2];
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uint8_t error=0;
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uint16_t i=0;
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//-- write I2C sensor address and command --
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 0); // I2C Adr
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switch(eSHT2xMeasureType)
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{ case HUMIDITY: error |= i2c_write(&TWIE, TRIG_RH_MEASUREMENT_POLL); break;
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case TEMP: error |= i2c_write(&TWIE, TRIG_T_MEASUREMENT_POLL); break;
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default: assert(0);
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}
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_delay_us(20);
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i2c_stop(&TWIE);
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//-- poll every 10ms for measurement ready. Timeout after 20 retries (200ms)--
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do
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{
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_delay_us(10000); //delay 10ms Max delay is 0.2s (20*10ms = 200ms)
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if(i++ >= 20) break;
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} while(i2c_start(&TWIE, I2C_SHT2x_ADR, 1) == ACK_ERROR);
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if (i>=20) error |= TIME_OUT_ERROR;
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//-- read two data bytes and one checksum byte --
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pMeasurand->s16.u8H = data[0] = i2c_read(&TWIE, I2C_ACK);
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pMeasurand->s16.u8L = data[1] = i2c_read(&TWIE, I2C_ACK);
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checksum= i2c_read(&TWIE, I2C_NACK);
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//-- verify checksum --
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error |= i2c_SHT2x_CheckCrc (data,2,checksum);
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i2c_stop(&TWIE);
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return error;
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}
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//===========================================================================
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uint8_t i2c_SHT2x_SoftReset()
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//===========================================================================
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{
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uint8_t error=0;
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 0);
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error |= i2c_write(&TWIE, SOFT_RESET);
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i2c_stop(&TWIE);
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_delay_ms(15);
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return error;
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}
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//==============================================================================
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float i2c_SHT2x_CalcRH(uint16_t sRH)
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// --- The original formula from SENSIRION is wrong! ---
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//==============================================================================
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{
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float humidityRH;
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sRH &= ~0x0003;
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//-- calculate relative humidity [%RH] --
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humidityRH = (float)sRH / RESOLUTION_16; //RH = -6 + 125 * sRH/2^16;
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humidityRH = humidityRH * CONSTANT_125;
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humidityRH = humidityRH - CONSTANT_6;
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return humidityRH;
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}
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//==============================================================================
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float i2c_SHT2x_CalcTemperatureC(uint16_t sT)
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// --- The original formula from SENSIRION is wrong! ---
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//==============================================================================
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{
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float temperatureC;
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sT &= ~0x0003;
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//-- calculate temperature [°C] --
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temperatureC = (float)sT / RESOLUTION_16; //T= -46.85 + 175.72 * ST/2^16
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temperatureC = temperatureC * CONSTANT_175_72;
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temperatureC = temperatureC - CONSTANT_46_85;
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return temperatureC;
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}
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//==============================================================================
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uint8_t i2c_SHT2x_GetSerialNumber(uint8_t SerialNumber[])
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//==============================================================================
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{
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uint8_t error=0; //error variable
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//Read from memory location 1
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 0); //I2C address
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error |= i2c_write(&TWIE, CMD_CHIP_MEMORY_LOC_1); //Command for readout on-chip memory
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error |= i2c_write(&TWIE, ADR_CHIP_MEMORY_LOC_1); //on-chip memory address
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i2c_stop(&TWIE);
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 1); //I2C read address
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SerialNumber[5] = i2c_read(&TWIE, I2C_ACK); //Read SNB_3
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i2c_read(&TWIE, I2C_ACK); //Read CRC SNB_3 (CRC is not analyzed)
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SerialNumber[4] = i2c_read(&TWIE, I2C_ACK); //Read SNB_2
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i2c_read(&TWIE, I2C_ACK); //Read CRC SNB_2 (CRC is not analyzed)
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SerialNumber[3] = i2c_read(&TWIE, I2C_ACK); //Read SNB_1
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i2c_read(&TWIE, I2C_ACK);; //Read CRC SNB_1 (CRC is not analyzed)
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SerialNumber[2] = i2c_read(&TWIE, I2C_ACK); //Read SNB_0
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i2c_read(&TWIE, I2C_NACK); //Read CRC SNB_0 (CRC is not analyzed)
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i2c_stop(&TWIE);
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//Read from memory location 2
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 0); //I2C address
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error |= i2c_write(&TWIE, CMD_CHIP_MEMORY_LOC_2); //Command for readout on-chip memory
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error |= i2c_write(&TWIE, ADR_CHIP_MEMORY_LOC_2); //on-chip memory address
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i2c_stop(&TWIE);
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error |= i2c_start(&TWIE, I2C_SHT2x_ADR, 1); //I2C address
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SerialNumber[1] = i2c_read(&TWIE, I2C_ACK); //Read SNC_1
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SerialNumber[0] = i2c_read(&TWIE, I2C_ACK); //Read SNC_0
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i2c_read(&TWIE, I2C_ACK); //Read CRC SNC0/1 (CRC is not analyzed)
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SerialNumber[7] = i2c_read(&TWIE, I2C_ACK); //Read SNA_1
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SerialNumber[6] = i2c_read(&TWIE, I2C_ACK); //Read SNA_0
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i2c_read(&TWIE, I2C_NACK); //Read CRC SNA0/1 (CRC is not analyzed)
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i2c_stop(&TWIE);
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return error;
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} |