Intermediate
20 min

Read conductivity, salinity, and TDS (PPM) in the water using EZO-EC™ and STM32F407VGT6

For various applications from chemical production to hydroponics

EZO Carrier Click - Conductivity with Clicker 4 for STM32F4

Published Mar 04, 2024

Click board™

EZO Carrier Click - Conductivity

Dev Board

Clicker 4 for STM32F4

Compiler

NECTO Studio

MCU

STM32F407VGT6

Accurate water chemistry analysis solution compatible with conductivity probes of various conductance levels (from K 0.01 to K 10.2)

A

A

Hardware Overview

How does it work?

EZO Carrier Click - Conductivity is based on the EZO-EC™, an ISO 7888 compliant embedded conductivity circuit board from Atlas Scientific. This is a versatile and accurate solution for measuring conductivity, salinity, and Total Dissolved Solids (TDS) in various applications from chemical production to hydroponics. With a conductivity range of 0.07 to over 500,000 μS/cm, it can also accurately measure salinity up to 42 PSU (ppt), TDS as ppm, and specific gravity of seawater between 1.00 and 1.300. This advanced module offers the precision and functionality comparable to high-end bench-top conductivity meters, making it an ideal choice for embedding into projects that require reliable water chemistry measurements. Boasting an accuracy of +/- 2% and a quick EC reading time of 600ms, the EZO-EC™ supports probes ranging from K 0.01 to K 10.2 of any brand. It allows for both two-point and three-point

calibration, ensuring precise measurements. Additionally, it features temperature compensation for more accurate readings across various conditions. This circuit is a very sensitive device, and its sensitivity gives it accuracy. That’s why the EZO-EC™ needs to be isolated from the host MCU; therefore, this Click™ board comes with the Si8400AB, a bidirectional isolator from Skyworks. The isolator provides standard bidirectional and I2C communication with a clock frequency of up to 1.7MHz. So, to eliminate the electrical noise, besides the Si8400AB isolator, the power supply voltage is also isolated. For this purpose, this Click™ board is equipped with the ROE-0505S, a DC/DC converter from Recom. EZO Carrier Click - Conductivity can use a standard 2-wire UART interface to communicate with the host MCU with the default baud rate of 9600bps. While using the UART interface, you can use the library we provide

or a simple ASCII set of commands. You can also choose a standard 2-wire I2C interface over the COMM SEL jumpers. From calibration to timed readings, the Atlas Scientific EZO-EC™ circuit is a drop-in solution to a complex measurement. It features sleep mode, continuous operation, find function, export/import calibration, on-module status LED, and many more features detailed and described in the attached datasheet. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

EZO Carrier Click - Conductivity hardware overview image

Features overview

Development board

Clicker 4 for STM32F4 is a compact development board designed as a complete solution that you can use to quickly build your own gadgets with unique functionalities. Featuring an STM32F407VGT6 MCU, four mikroBUS™ sockets for Click boards™ connectivity, power management, and more, it represents a perfect solution for the rapid development of many different types of applications. At its core is an STM32F407VGT6 MCU, a powerful microcontroller by STMicroelectronics based on the high-performance

Arm® Cortex®-M4 32-bit processor core operating at up to 168 MHz frequency. It provides sufficient processing power for the most demanding tasks, allowing Clicker 4 to adapt to any specific application requirements. Besides two 1x20 pin headers, four improved mikroBUS™ sockets represent the most distinctive connectivity feature, allowing access to a huge base of Click boards™, growing on a daily basis. Each section of Clicker 4 is clearly marked, offering an intuitive and clean interface. This makes working with the

development board much simpler and, thus, faster. The usability of Clicker 4 doesn’t end with its ability to accelerate the prototyping and application development stages: it is designed as a complete solution that can be implemented directly into any project, with no additional hardware modifications required. Four mounting holes [4.2mm/0.165”] at all four corners allow simple installation by using mounting screws.

Clicker 4 for STM32F4 double image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M4

MCU Memory (KB)

10

Silicon Vendor

STMicroelectronics

Pin count

100

RAM (Bytes)

100

You complete me!

Accessories

The Atlas Scientific conductivity probe, known as Probe K, stands out for its stable and precise readings across a wide range of conductivity. Free from fringe effects, it ensures accuracy within a range of 5 to 200,000μS/cm, with an impressive accuracy of ±2%. Responding swiftly, it achieves 90% accuracy in just 1 second, making it ideal for real-time monitoring applications. With a broad temperature range from 1 to 110°C, it can withstand diverse environmental conditions. Its robust construction allows for a maximum pressure of 3,447kPa (500PSI) and a maximum depth of 352 meters (1,157 feet). A 1-meter cable provides installation flexibility. Probe K boasts a long recalibration interval of approximately ten years, aligning with its equally impressive life expectancy. Probe K ensures reliable conductivity measurements for a decade and beyond with these features.

EZO Carrier Click - Conductivity accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
ID COMM
PA4
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
UART TX
PA2
TX
UART RX
PA3
RX
I2C Clock
PB10
SCL
I2C Data
PB11
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

EZO Carrier Click - Conductivity Schematic schematic

Step by step

Project assembly

Clicker 4 for STM32F4 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Clicker 4 for STM32F4 as your development board.

Clicker 4 for STM32F4 front image hardware assembly
LTE IoT 5 Click front image hardware assembly
LTE IoT 5 Click complete accessories setup image hardware assembly
Clicker 4 STM32F4 Access MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Clicker 4 for STM32F4 HA MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for EZO Carrier Click - Conductivity driver.

Key functions:

  • ezocarrierec_send_cmd - Send command function

  • ezocarrierec_send_cmd_with_par - Send command function with parameter

  • ezocarrierec_send_cmd_check - Check the sent command

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * @file main.c
 * @brief EZO Carrier EC Click Example.
 *
 * # Description
 * This example demonstrates the use of EZO Carrier EC click board by processing
 * the incoming data and displaying them on the USB UART.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver, performs the click default factory reset, and single point calibration.
 *
 * ## Application Task
 * Reads and processes all incoming conductivity data from the probe, and displays them on the USB UART in uS.
 *
 * ## Additional Function
 * - static void ezocarrierec_clear_app_buf ( void )
 * - static void ezocarrierec_log_app_buf ( void )
 * - static err_t ezocarrierec_process ( ezocarrierec_t *ctx )
 * - static err_t ezocarrierec_rsp_check ( ezocarrierec_t *ctx, uint8_t *rsp )
 * - static void ezocarrierec_error_check ( err_t error_flag )
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "ezocarrierec.h"

// Application buffer size
#define APP_BUFFER_SIZE             200
#define PROCESS_BUFFER_SIZE         200

static ezocarrierec_t ezocarrierec;
static log_t logger;

static uint8_t app_buf[ APP_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;
static err_t error_flag;

/**
 * @brief EZO Carrier EC clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @note None.
 */
static void ezocarrierec_clear_app_buf ( void );

/**
 * @brief EZO Carrier EC log application buffer.
 * @details This function logs data from application buffer to USB UART.
 * @note None.
 */
static void ezocarrierec_log_app_buf ( void );

/**
 * @brief EZO Carrier EC data reading function.
 * @details This function reads data from device and concatenates data to application buffer. 
 * @param[in] ctx : Click context object.
 * See #ezocarrierec_t object definition for detailed explanation.
 * @return @li @c  0 - Read some data.
 *         @li @c -1 - Nothing is read.
 * See #err_t definition for detailed explanation.
 * @note None.
 */
static err_t ezocarrierec_process ( ezocarrierec_t *ctx );

/**
 * @brief Response check.
 * @details This function checks for response and
 * returns the status of response.
 * @param[in] rsp  Expected response.
 * @return @li @c  0 - OK response.
 *         @li @c -1 - Error response.
 *         @li @c -2 - Timeout error.
 * See #err_t definition for detailed explanation.
 */
static err_t ezocarrierec_rsp_check ( ezocarrierec_t *ctx, uint8_t *rsp );

/**
 * @brief Check for errors.
 * @details This function checks for different types of
 * errors and logs them on UART or logs the response if no errors occured.
 * @param[in] error_flag  Error flag to check.
 */
static void ezocarrierec_error_check ( err_t error_flag );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ezocarrierec_cfg_t ezocarrierec_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    ezocarrierec_cfg_setup( &ezocarrierec_cfg );
    EZOCARRIEREC_MAP_MIKROBUS( ezocarrierec_cfg, MIKROBUS_1 );
    if ( UART_ERROR == ezocarrierec_init( &ezocarrierec, &ezocarrierec_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }

    log_printf( &logger, "Device status \r\n" );
    ezocarrierec_send_cmd( &ezocarrierec, EZOCARRIEREC_CMD_STATUS );
    error_flag = ezocarrierec_rsp_check( &ezocarrierec, EZOCARRIEREC_RSP_OK );
    ezocarrierec_error_check( error_flag );

    log_printf( &logger, "Factory reset \r\n" );
    ezocarrierec_send_cmd( &ezocarrierec, EZOCARRIEREC_CMD_FACTORY );
    error_flag = ezocarrierec_rsp_check( &ezocarrierec, EZOCARRIEREC_RSP_READY );
    ezocarrierec_error_check( error_flag );

    #define PROBE_TYPE   "1.0"
    log_printf( &logger, "Seting Probe type \r\n" );
    ezocarrierec_send_cmd_with_par( &ezocarrierec, EZOCARRIEREC_CMD_SET_PROBE_TYPE, PROBE_TYPE );
    error_flag = ezocarrierec_rsp_check( &ezocarrierec, EZOCARRIEREC_RSP_OK );
    ezocarrierec_error_check( error_flag );

    log_printf( &logger, "Device info \r\n" );
    ezocarrierec_send_cmd( &ezocarrierec, EZOCARRIEREC_CMD_DEV_INFO );
    error_flag = ezocarrierec_rsp_check( &ezocarrierec, EZOCARRIEREC_RSP_OK );
    ezocarrierec_error_check( error_flag );

    #define DRY_CALIBRATION   "dry"
    log_printf( &logger, "Dry calibration \r\n" );
    ezocarrierec_send_cmd_with_par( &ezocarrierec, EZOCARRIEREC_CMD_CAL, DRY_CALIBRATION );
    error_flag = ezocarrierec_rsp_check( &ezocarrierec, EZOCARRIEREC_RSP_OK );
    ezocarrierec_error_check( error_flag );

    uint8_t n_cnt = 0;
    uint8_t last_reading[ APP_BUFFER_SIZE ] = { 0 };
    ezocarrierec_clear_app_buf( );
    ezocarrierec_send_cmd( &ezocarrierec, EZOCARRIEREC_CMD_SINGLE_READ );
    ezocarrierec_process ( &ezocarrierec );
    strcpy( last_reading, app_buf );
    log_printf( &logger, "Single point calibration \r\n" );
    log_printf( &logger, "Waiting for stable readings \r\n" );
    while ( n_cnt <= 5 )
    {
        if ( EZOCARRIEREC_OK == ezocarrierec_process ( &ezocarrierec ) )
        {  
            if ( 0 == strstr( app_buf, last_reading ) )
            {
                n_cnt++;
            }
            else
            {
                strcpy( last_reading, app_buf );
                n_cnt = 0;
            }
        }
        log_printf( &logger, "- " );
        Delay_ms( 1000 );
        ezocarrierec_clear_app_buf( );
    }
    #define CALIBRATION_VALUE   "80"
    log_printf( &logger, "Calibration \r\n" );
    ezocarrierec_send_cmd_with_par( &ezocarrierec, EZOCARRIEREC_CMD_CAL, CALIBRATION_VALUE );
    error_flag = ezocarrierec_rsp_check( &ezocarrierec, EZOCARRIEREC_RSP_OK );
    ezocarrierec_error_check( error_flag );

    #define DISABLE_CONT_READ   "0"
    log_printf( &logger, "Disable continuous reading mode \r\n" );
    ezocarrierec_send_cmd_with_par( &ezocarrierec, EZOCARRIEREC_CMD_CONT_READ, DISABLE_CONT_READ );
    error_flag = ezocarrierec_rsp_check( &ezocarrierec, EZOCARRIEREC_RSP_OK );
    ezocarrierec_error_check( error_flag );

    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    log_printf( &logger, "Reading... \r\n" );
    ezocarrierec_send_cmd( &ezocarrierec, EZOCARRIEREC_CMD_SINGLE_READ );
    error_flag = ezocarrierec_rsp_check( &ezocarrierec, EZOCARRIEREC_RSP_OK );
    ezocarrierec_error_check( error_flag );
    Delay_ms( 5000 );
}

void main ( void ) 
{
    application_init( );

    for ( ; ; ) 
    {
        application_task( );
    }
}

static void ezocarrierec_clear_app_buf ( void ) 
{
    memset( app_buf, 0, app_buf_len );
    app_buf_len = 0;
}

static void ezocarrierec_log_app_buf ( void )
{
    for ( int32_t buf_cnt = 0; buf_cnt < app_buf_len; buf_cnt++ )
    {
        log_printf( &logger, "%c", app_buf[ buf_cnt ] );
    }
}

static err_t ezocarrierec_process ( ezocarrierec_t *ctx ) 
{
    uint8_t rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t overflow_bytes = 0;
    int32_t rx_cnt = 0;
    int32_t rx_size = ezocarrierec_generic_read( ctx, rx_buf, PROCESS_BUFFER_SIZE );
    if ( ( rx_size > 0 ) && ( rx_size <= APP_BUFFER_SIZE ) ) 
    {
        if ( ( app_buf_len + rx_size ) > APP_BUFFER_SIZE ) 
        {
            overflow_bytes = ( app_buf_len + rx_size ) - APP_BUFFER_SIZE;
            app_buf_len = APP_BUFFER_SIZE - rx_size;
            memmove ( app_buf, &app_buf[ overflow_bytes ], app_buf_len );
            memset ( &app_buf[ app_buf_len ], 0, overflow_bytes );
        }
        for ( rx_cnt = 0; rx_cnt < rx_size; rx_cnt++ ) 
        {
            if ( rx_buf[ rx_cnt ] ) 
            {
                app_buf[ app_buf_len++ ] = rx_buf[ rx_cnt ];
            }
        }
        return EZOCARRIEREC_OK;
    }
    return EZOCARRIEREC_ERROR;
}

static err_t ezocarrierec_rsp_check ( ezocarrierec_t *ctx, uint8_t *rsp )
{
    uint32_t timeout_cnt = 0;
    uint32_t timeout = 10000;
    err_t error_flag = EZOCARRIEREC_OK;
    ezocarrierec_clear_app_buf( );
    while ( ( 0 == strstr( app_buf, rsp ) ) &&
    ( 0 == strstr( app_buf, EZOCARRIEREC_RSP_ERROR ) ) )
    {
        error_flag |= ezocarrierec_process( ctx );
        if ( timeout_cnt++ > timeout )
        {
            ezocarrierec_clear_app_buf( );
            return EZOCARRIEREC_ERROR_TIMEOUT;
        }
        Delay_ms( 1 );
    }
    Delay_ms( 100 );
    error_flag |= ezocarrierec_process( ctx );
    if ( strstr( app_buf, rsp ) )
    {
        return EZOCARRIEREC_OK;
     }
    else if ( strstr( app_buf, EZOCARRIEREC_RSP_ERROR ) )
    {
        return EZOCARRIEREC_ERROR;
    }
    else
    {
        return EZOCARRIEREC_ERROR;
    }
}

static void ezocarrierec_error_check ( err_t error_flag )
{
    switch ( error_flag )
    {
        case EZOCARRIEREC_OK:
        {
            ezocarrierec_log_app_buf( );
            break;
        }
        case EZOCARRIEREC_ERROR:
        {
            log_error( &logger, " Error!" );
            break;
        }
        case EZOCARRIEREC_ERROR_TIMEOUT:
        {
            log_error( &logger, " Timeout!" );
            break;
        }
        default:
        {
            log_error( &logger, " Unknown!" );
            break;
        }
    }
    log_printf( &logger, "- - - - - - - - - - - - - - -\r\n" );
    Delay_ms( 500 );
}

// ------------------------------------------------------------------------ END

Additional Support

Resources