Intermediate
20 min

Determine the electron activity in a liquid, essential for understanding its ORP, with EZO-ORP™ and STM32F031K6

Oxidation/Reduction Potential (ORP) - Where it's crucial to ensure water is free from pathogens!

EZO Carrier Click - ORP with Nucleo 32 with STM32F031K6 MCU

Published Oct 01, 2024

Click board™

EZO Carrier Click - ORP

Dev. board

Nucleo 32 with STM32F031K6 MCU

Compiler

NECTO Studio

MCU

STM32F031K6

Measure the ORP of liquids for evaluating water quality and chemical reactions in water treatment, environmental monitoring, and chemical production

A

A

Hardware Overview

How does it work?

EZO Carrier Click - ORP is based on the EZO-ORP™, an ISO 11271 compliant embedded ORP (Oxidation/Reduction Potential) circuit board from Atlas Scientific. It allows you to interface any type and brand of measurement probe, which determines the liquid's oxidation/reduction potential in your application by sinking the probe into the solvent you want to measure the electron activity. The EZO Carrier Click - ORP comes with the BNC connector for interfacing the appropriate probe, like the Consumer Grade ORP probe. The EZO-ORP™ 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. This circuit is a very sensitive device, and the sensitivity gives it its accuracy. It can read micro-voltages that are bleeding into the water from unnatural sources such as pumps, solenoid valves, or other probes/sensors. 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 - ORP 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-ORP™ 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 - ORP hardware overview image

Features overview

Development board

Nucleo 32 with STM32F031K6 MCU board provides an affordable and flexible platform for experimenting with STM32 microcontrollers in 32-pin packages. Featuring Arduino™ Nano connectivity, it allows easy expansion with specialized shields, while being mbed-enabled for seamless integration with online resources. The

board includes an on-board ST-LINK/V2-1 debugger/programmer, supporting USB reenumeration with three interfaces: Virtual Com port, mass storage, and debug port. It offers a flexible power supply through either USB VBUS or an external source. Additionally, it includes three LEDs (LD1 for USB communication, LD2 for power,

and LD3 as a user LED) and a reset push button. The STM32 Nucleo-32 board is supported by various Integrated Development Environments (IDEs) such as IAR™, Keil®, and GCC-based IDEs like AC6 SW4STM32, making it a versatile tool for developers.

Nucleo 32 with STM32F031K6 MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

32

Silicon Vendor

STMicroelectronics

Pin count

32

RAM (Bytes)

4096

You complete me!

Accessories

Click Shield for Nucleo-32 is the perfect way to expand your development board's functionalities with STM32 Nucleo-32 pinout. The Click Shield for Nucleo-32 provides two mikroBUS™ sockets to add any functionality from our ever-growing range of Click boards™. We are fully stocked with everything, from sensors and WiFi transceivers to motor control and audio amplifiers. The Click Shield for Nucleo-32 is compatible with the STM32 Nucleo-32 board, providing an affordable and flexible way for users to try out new ideas and quickly create prototypes with any STM32 microcontrollers, choosing from the various combinations of performance, power consumption, and features. The STM32 Nucleo-32 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/programmer and come with the STM32 comprehensive software HAL library and various packaged software examples. This development platform provides users with an effortless and common way to combine the STM32 Nucleo-32 footprint compatible board with their favorite Click boards™ in their upcoming projects.

Click Shield for Nucleo-32 accessories 1 image

Consumer-grade ORP probe from Atlas Scientific is an excellent option for various water testing needs, environmental monitoring, basic lab experiments, and initial product development stages. Designed for light-duty applications, it offers reliable ORP measurements within a range of -1100mV to +1100mV with an accuracy of ±1.1mV. With a rapid response time of 95% in just 1 second, it provides quick data acquisition for timely analysis. Operating effectively within a temperature range of 1 to 60°C, it suits diverse environmental conditions. However, it's essential to note that this probe isn't suitable for use in strong acids, bases, or industrial equipment environments. It is designed for moderate test depths with a maximum pressure tolerance of 50 PSI and a maximum depth rating of 35 meters (114 feet). Additionally, its 1-meter cable length offers convenience in installation and maneuverability.

EZO Carrier Click - ORP 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
PA10
TX
UART RX
PA9
RX
I2C Clock
PB6
SCL
I2C Data
PB7
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

EZO Carrier Click - ORP Schematic schematic

Step by step

Project assembly

Click Shield for Nucleo-144 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Nucleo 32 with STM32F031K6 MCU as your development board.

Click Shield for Nucleo-144 front image hardware assembly
Nucleo 144 with STM32L4A6ZG MCU front image hardware assembly
Stepper 22 Click front image hardware assembly
Prog-cut hardware assembly
Stepper 22 Click complete accessories setup image hardware assembly
Nucleo-32 with STM32 MCU 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
STM32 M4 Clicker HA MCU/Select 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

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

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

Key functions:

  • ezocarrierorp_send_cmd - Send command function

  • ezocarrierorp_send_cmd_with_par - Send command function with parameter

  • ezocarrierorp_send_cmd_check - Check the sent command

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief EZO Carrier ORP Click Example.
 *
 * # Description
 * This example demonstrates the use of EZO Carrier ORP 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 
 * with a calibration solutio with 225 mV ORP value.
 *
 * ## Application Task
 * Reads and processes all incoming oxidation-reduction potential data from the probe, and displays them on the USB UART in mV.
 *
 * ## Additional Function
 * - static void ezocarrierorp_clear_app_buf ( void )
 * - static void ezocarrierorp_log_app_buf ( void )
 * - static err_t ezocarrierorp_process ( ezocarrierorp_t *ctx )
 * - static err_t ezocarrierorp_rsp_check ( ezocarrierorp_t *ctx, uint8_t *rsp )
 * - static void ezocarrierorp_error_check ( err_t error_flag )
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "ezocarrierorp.h"

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

static ezocarrierorp_t ezocarrierorp;
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 ORP clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @note None.
 */
static void ezocarrierorp_clear_app_buf ( void );

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

/**
 * @brief EZO Carrier ORP data reading function.
 * @details This function reads data from device and concatenates data to application buffer. 
 * @param[in] ctx : Click context object.
 * See #ezocarrierorp_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 ezocarrierorp_process ( ezocarrierorp_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 ezocarrierorp_rsp_check ( ezocarrierorp_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 ezocarrierorp_error_check ( err_t error_flag );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ezocarrierorp_cfg_t ezocarrierorp_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.
    ezocarrierorp_cfg_setup( &ezocarrierorp_cfg );
    EZOCARRIERORP_MAP_MIKROBUS( ezocarrierorp_cfg, MIKROBUS_1 );
    if ( UART_ERROR == ezocarrierorp_init( &ezocarrierorp, &ezocarrierorp_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }

    log_printf( &logger, "Device status \r\n" );
    ezocarrierorp_send_cmd( &ezocarrierorp, EZOCARRIERORP_CMD_STATUS );
    error_flag = ezocarrierorp_rsp_check( &ezocarrierorp, EZOCARRIERORP_RSP_OK );
    ezocarrierorp_error_check( error_flag );

    log_printf( &logger, "Factory reset \r\n" );
    ezocarrierorp_send_cmd( &ezocarrierorp, EZOCARRIERORP_CMD_FACTORY );
    error_flag = ezocarrierorp_rsp_check( &ezocarrierorp, EZOCARRIERORP_RSP_READY );
    ezocarrierorp_error_check( error_flag );

    log_printf( &logger, "Device info \r\n" );
    ezocarrierorp_send_cmd( &ezocarrierorp, EZOCARRIERORP_CMD_DEV_INFO );
    error_flag = ezocarrierorp_rsp_check( &ezocarrierorp, EZOCARRIERORP_RSP_OK );
    ezocarrierorp_error_check( error_flag );

    uint8_t n_cnt = 0;
    uint8_t last_reading[ APP_BUFFER_SIZE ] = { 0 };
    ezocarrierorp_clear_app_buf( );
    ezocarrierorp_send_cmd( &ezocarrierorp, EZOCARRIERORP_CMD_SINGLE_READ );
    ezocarrierorp_process ( &ezocarrierorp );
    strcpy( last_reading, app_buf );
    log_printf( &logger, "Place the probe into the calibration solution,\r\n" );
    log_printf( &logger, "for single-point calibration \r\n" );
    Delay_ms( 5000 );
    log_printf( &logger, "Waiting for stable readings \r\n" );
    while ( n_cnt <= 5 )
    {
        if ( EZOCARRIERORP_OK == ezocarrierorp_process ( &ezocarrierorp ) )
        {  
            if ( 0 == strstr( app_buf, last_reading ) )
            {
                n_cnt++;
            }
            else
            {
                strcpy( last_reading, app_buf );
                n_cnt = 0;
            }
        }
        log_printf( &logger, "- " );
        Delay_ms( 1000 );
        ezocarrierorp_clear_app_buf( );
    }

    #define CALIBRATION_VALUE   "225"
    log_printf( &logger, "\r\n Calibration \r\n" );
    ezocarrierorp_send_cmd_with_par( &ezocarrierorp, EZOCARRIERORP_CMD_CAL, CALIBRATION_VALUE );
    error_flag = ezocarrierorp_rsp_check( &ezocarrierorp, EZOCARRIERORP_RSP_OK );
    ezocarrierorp_error_check( error_flag );

    #define DISABLE_CONT_READ   "0"
    log_printf( &logger, "Disable continuous reading mode \r\n" );
    ezocarrierorp_send_cmd_with_par( &ezocarrierorp, EZOCARRIERORP_CMD_CONT_READ, DISABLE_CONT_READ );
    error_flag = ezocarrierorp_rsp_check( &ezocarrierorp, EZOCARRIERORP_RSP_OK );
    ezocarrierorp_error_check( error_flag );
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    log_printf( &logger, "Reading... \r\n" );
    ezocarrierorp_send_cmd( &ezocarrierorp, EZOCARRIERORP_CMD_SINGLE_READ );
    error_flag = ezocarrierorp_rsp_check( &ezocarrierorp, EZOCARRIERORP_RSP_OK );
    ezocarrierorp_error_check( error_flag );
    Delay_ms( 5000 );
}

void main ( void ) 
{
    application_init( );

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

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

static void ezocarrierorp_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 ezocarrierorp_process ( ezocarrierorp_t *ctx ) 
{
    uint8_t rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t overflow_bytes = 0;
    int32_t rx_cnt = 0;
    int32_t rx_size = ezocarrierorp_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 EZOCARRIERORP_OK;
    }
    return EZOCARRIERORP_ERROR;
}

static err_t ezocarrierorp_rsp_check ( ezocarrierorp_t *ctx, uint8_t *rsp )
{
    uint32_t timeout_cnt = 0;
    uint32_t timeout = 10000;
    err_t error_flag = EZOCARRIERORP_OK;
    ezocarrierorp_clear_app_buf( );
    while ( ( 0 == strstr( app_buf, rsp ) ) &&
    ( 0 == strstr( app_buf, EZOCARRIERORP_RSP_ERROR ) ) )
    {
        error_flag |= ezocarrierorp_process( ctx );
        if ( timeout_cnt++ > timeout )
        {
            ezocarrierorp_clear_app_buf( );
            return EZOCARRIERORP_ERROR_TIMEOUT;
        }
        Delay_ms( 1 );
    }
    Delay_ms( 100 );
    error_flag |= ezocarrierorp_process( ctx );
    if ( strstr( app_buf, rsp ) )
    {
        return EZOCARRIERORP_OK;
     }
    else if ( strstr( app_buf, EZOCARRIERORP_RSP_ERROR ) )
    {
        return EZOCARRIERORP_ERROR;
    }
    else
    {
        return EZOCARRIERORP_ERROR;
    }
}

static void ezocarrierorp_error_check ( err_t error_flag )
{
    switch ( error_flag )
    {
        case EZOCARRIERORP_OK:
        {
            ezocarrierorp_log_app_buf( );
            break;
        }
        case EZOCARRIERORP_ERROR:
        {
            log_error( &logger, " Error!" );
            break;
        }
        case EZOCARRIERORP_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

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