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