environment4  2.1.0.0
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Environment 4 click

Environment 4 Click is a compact add-on board combining 4th-generation SHT humidity and SGP air-quality sensing solutions from Sensirion. This board features SHT41A-AD1B and SGP41, an I2C-configurable high-accuracy relative humidity/temperature combined with a MOx-based gas sensor. The SHT41A-AD1B offers linearized digital output alongside temperature/humidity accuracy up to ±0.3°C/±2RH. It performs best within the operating range of 5-60°C and 20-80RH. With the help of SGP41, which features a temperature-controlled micro hotplate, it also provides a humidity-compensated VOC and NOx-based indoor air quality signal.

click Product page


Click library

  • Author : Stefan Filipovic
  • Date : Dec 2022.
  • Type : I2C type

Software Support

We provide a library for the Environment 4 Click as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for Environment 4 Click driver.

Standard key functions :

Example key functions :

  • environment4_sht_read_meas_hp This function reads the temperature and humidity measurements with high precision from SHT41A device.
    err_t environment4_sht_read_meas_hp ( environment4_t *ctx, float *temp, float *hum );
  • environment4_sgp_exe_conditioning This function executes conditioning command for SGP41 device by using I2C serial interface.
    err_t environment4_sgp_exe_conditioning ( environment4_t *ctx, uint16_t comp_rh, uint16_t comp_t, uint16_t *sraw_voc );
  • environment4_sgp_meas_raw_signals This function measures raw signals for SGP41 device by using I2C serial interface.
    err_t environment4_sgp_meas_raw_signals ( environment4_t *ctx, uint16_t comp_rh, uint16_t comp_t, uint16_t *sraw_voc, uint16_t *sraw_nox );

Example Description

This example demonstrates the use of Environment 4 click board by reading the temperature and humidity data and calculating VOC and NOx indexes.

The demo application is composed of two sections :

Application Init

Initializes the driver, and reads and displays the SGP41 sensor unique serial number

and performs its build-in self-test. After that performs the SHT41 sensor software reset and reads its unique serial number. Finally, it initializes the sensirion gas index algorithm for VOC and NOx index calculation.

void application_init ( void )
{
log_cfg_t log_cfg;
environment4_cfg_t environment4_cfg;
LOG_MAP_USB_UART( log_cfg );
log_init( &logger, &log_cfg );
log_info( &logger, " Application Init " );
// Click initialization.
environment4_cfg_setup( &environment4_cfg );
ENVIRONMENT4_MAP_MIKROBUS( environment4_cfg, MIKROBUS_1 );
if ( I2C_MASTER_ERROR == environment4_init( &environment4, &environment4_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
uint16_t serial_num_sgp[ 3 ];
if ( ENVIRONMENT4_OK == environment4_sgp_get_serial_num ( &environment4, serial_num_sgp ) )
{
log_printf ( &logger, " SGP Serial number: 0x%.4X%.4X%.4X\r\n",
serial_num_sgp[ 0 ], serial_num_sgp[ 1 ], serial_num_sgp[ 2 ] );
}
uint8_t test_result_sgp;
if ( ENVIRONMENT4_OK == environment4_sgp_exe_self_test ( &environment4, &test_result_sgp ) )
{
log_printf ( &logger, " SGP Self test result: " );
if ( ENVIRONMENT4_SGP_SELF_TEST_OK == test_result_sgp )
{
log_printf ( &logger, "OK\r\n" );
}
else
{
if ( ENVIRONMENT4_SGP_SELF_TEST_VOC_PIXEL == test_result_sgp )
{
log_printf ( &logger, "VOC pixel fail; " );
}
if ( ENVIRONMENT4_SGP_SELF_TEST_NOX_PIXEL == test_result_sgp )
{
log_printf ( &logger, "NOx pixel fail; " );
}
log_printf ( &logger, "\r\n" );
}
}
if ( ENVIRONMENT4_OK == environment4_sht_soft_reset ( &environment4 ) )
{
log_printf ( &logger, " SHT Software reset\r\n" );
Delay_1sec ( );
}
uint32_t serial_num_sht;
if ( ENVIRONMENT4_OK == environment4_sht_read_serial_num ( &environment4, &serial_num_sht ) )
{
log_printf ( &logger, " SHT Serial number: 0x%.8LX\r\n", serial_num_sht );
}
log_printf ( &logger, " Initialize Gas Index algorithm for VOC and NOx\r\n" );
log_info( &logger, " Application Task " );
}

Application Task

Reads the temperature (degC) and the relative humidity (RH) data from SHT41 sensor with high precision.

For the first 10 seconds it executes NOx conditioning and after that it reads the raw signals for VOC and NOx data and processes them with sensirion's gas index algorithm for calculating VOC and NOx indexes. All data will be displayed on the USB UART approximately once per second.

void application_task ( void )
{
float temperature, humidity;
uint16_t comp_rh, comp_t, sraw_voc, sraw_nox;
int32_t voc_index, nox_index;
static uint8_t conditioning_num = 10;
Delay_ms ( 1000 );
if ( ENVIRONMENT4_OK == environment4_sht_read_meas_hp ( &environment4, &temperature, &humidity ) )
{
log_printf ( &logger, "\r\n Temperature: %.2f degC\r\n", temperature );
log_printf ( &logger, " Humidity: %.2f %%RH\r\n", humidity );
comp_rh = ( uint16_t ) ( humidity * ENVIRONMENT4_SHT_DATA_RESOLUTION /
comp_t = ( uint16_t ) ( ( temperature - ENVIRONMENT4_SHT_ABS_MIN_TEMP ) * ENVIRONMENT4_SHT_DATA_RESOLUTION /
if ( conditioning_num )
{
if ( ENVIRONMENT4_OK == environment4_sgp_exe_conditioning ( &environment4, comp_rh, comp_t, &sraw_voc ) )
{
conditioning_num--;
}
}
else
{
if ( ENVIRONMENT4_OK == environment4_sgp_meas_raw_signals ( &environment4, comp_rh, comp_t, &sraw_voc, &sraw_nox ) )
{
GasIndexAlgorithm_process( &voc_params, ( int32_t ) sraw_voc, &voc_index );
GasIndexAlgorithm_process( &nox_params, ( int32_t ) sraw_nox, &nox_index );
log_printf ( &logger, " VOC Index: %ld\r\n", voc_index );
log_printf ( &logger, " NOx Index: %ld\r\n", nox_index );
}
}
}
}

Note

Time required for reliably detecting VOC and NOx events on switching ON is typically less than 60 seconds.

Refer to the SGP41 sensor datasheet for more timing specifications.

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

  • MikroSDK.Board
  • MikroSDK.Log
  • Click.Environment4

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all MikroElektronika compilers.


GasIndexAlgorithm_ALGORITHM_TYPE_VOC
#define GasIndexAlgorithm_ALGORITHM_TYPE_VOC
Definition: sensirion_gas_index_algorithm.h:58
ENVIRONMENT4_SHT_ABS_MAX_HUM
#define ENVIRONMENT4_SHT_ABS_MAX_HUM
Definition: environment4.h:126
ENVIRONMENT4_SHT_ABS_MAX_TEMP
#define ENVIRONMENT4_SHT_ABS_MAX_TEMP
Definition: environment4.h:124
ENVIRONMENT4_SHT_ABS_MIN_HUM
#define ENVIRONMENT4_SHT_ABS_MIN_HUM
Definition: environment4.h:125
ENVIRONMENT4_OK
@ ENVIRONMENT4_OK
Definition: environment4.h:193
ENVIRONMENT4_SGP_SELF_TEST_VOC_PIXEL
#define ENVIRONMENT4_SGP_SELF_TEST_VOC_PIXEL
Definition: environment4.h:112
environment4_sht_read_serial_num
err_t environment4_sht_read_serial_num(environment4_t *ctx, uint32_t *serial_num)
Environment 4 sht read serial num function.
ENVIRONMENT4_SHT_DATA_RESOLUTION
#define ENVIRONMENT4_SHT_DATA_RESOLUTION
Definition: environment4.h:122
environment4_cfg_t
Environment 4 Click configuration object.
Definition: environment4.h:178
environment4_sht_read_meas_hp
err_t environment4_sht_read_meas_hp(environment4_t *ctx, float *temp, float *hum)
Environment 4 sht read meas hp function.
environment4_init
err_t environment4_init(environment4_t *ctx, environment4_cfg_t *cfg)
Environment 4 initialization function.
ENVIRONMENT4_SGP_SELF_TEST_NOX_PIXEL
#define ENVIRONMENT4_SGP_SELF_TEST_NOX_PIXEL
Definition: environment4.h:113
environment4_sgp_exe_conditioning
err_t environment4_sgp_exe_conditioning(environment4_t *ctx, uint16_t comp_rh, uint16_t comp_t, uint16_t *sraw_voc)
Environment 4 sgp exe conditioning function.
GasIndexAlgorithm_process
void GasIndexAlgorithm_process(GasIndexAlgorithmParams *params, int32_t sraw, int32_t *gas_index)
application_task
void application_task(void)
Definition: main.c:117
GasIndexAlgorithm_ALGORITHM_TYPE_NOX
#define GasIndexAlgorithm_ALGORITHM_TYPE_NOX
Definition: sensirion_gas_index_algorithm.h:59
environment4_sgp_exe_self_test
err_t environment4_sgp_exe_self_test(environment4_t *ctx, uint8_t *test_result)
Environment 4 sgp exe self test function.
GasIndexAlgorithm_init
void GasIndexAlgorithm_init(GasIndexAlgorithmParams *params, int32_t algorithm_type)
ENVIRONMENT4_SHT_ABS_MIN_TEMP
#define ENVIRONMENT4_SHT_ABS_MIN_TEMP
Definition: environment4.h:123
environment4_sgp_get_serial_num
err_t environment4_sgp_get_serial_num(environment4_t *ctx, uint16_t *serial_num)
Environment 4 sgp get serial num function.
application_init
void application_init(void)
Definition: main.c:42
ENVIRONMENT4_MAP_MIKROBUS
#define ENVIRONMENT4_MAP_MIKROBUS(cfg, mikrobus)
MikroBUS pin mapping.
Definition: environment4.h:152
ENVIRONMENT4_SGP_SELF_TEST_OK
#define ENVIRONMENT4_SGP_SELF_TEST_OK
Environment 4 SGP41 self test bit values.
Definition: environment4.h:111
environment4_cfg_setup
void environment4_cfg_setup(environment4_cfg_t *cfg)
Environment 4 configuration object setup function.
environment4_sgp_meas_raw_signals
err_t environment4_sgp_meas_raw_signals(environment4_t *ctx, uint16_t comp_rh, uint16_t comp_t, uint16_t *sraw_voc, uint16_t *sraw_nox)
Environment 4 sgp meas raw signals function.
environment4_t
Environment 4 Click context object.
Definition: environment4.h:164
environment4_sht_soft_reset
err_t environment4_sht_soft_reset(environment4_t *ctx)
Environment 4 sht soft reset function.