Intermediate
20 min

Determine the dissolved oxygen level in a liquid with EZO-DO™ and PIC32MZ2048EFM100

ISO 5814 compliant embedded dissolved oxygen circuit

EZO Carrier Click - Oxygen with Curiosity PIC32 MZ EF

Published Feb 14, 2024

Click board™

EZO Carrier Click - Oxygen

Dev. board

Curiosity PIC32 MZ EF

Compiler

NECTO Studio

MCU

PIC32MZ2048EFM100

Accurately measure the amount of oxygen dissolved in liquids like water, and enjoy tasks such as monitoring water quality in aquariums or conducting scientific experiments where precise oxygen measurement is crucial

A

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Hardware Overview

How does it work?

EZO Carrier Click - Oxygen is based on the EZO-DO™, an ISO 5814 compliant embedded dissolved oxygen circuit board from Atlas Scientific. It allows you to interface any galvanic measurement probe, which determines the dissolved oxygen of a liquid in your application, by sinking the probe into the solvent you want to measure the oxygen. The EZO Carrier Click - Oxygen comes with the BNC connector for interfacing the appropriate probe, which MIKROE also offers. The EZO-DO™ 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. The EZO-DO™ circuit is a very sensitive

device, and the sensitivity is what gives this circuit 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. The EZO-DO™ has a flexible calibration protocol allowing for single-point, two-point, or three-point calibration. The temperature compensation should be taken into account. The EZO-DO™ features sleep mode, continuous operation, find function, export/import calibration, on-module status LED, and many more features. EZO Carrier Click - Oxygen 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. 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 - Oxygen hardware overview image

Features overview

Development board

Curiosity PIC32 MZ EF development board is a fully integrated 32-bit development platform featuring the high-performance PIC32MZ EF Series (PIC32MZ2048EFM) that has a 2MB Flash, 512KB RAM, integrated FPU, Crypto accelerator, and excellent connectivity options. It includes an integrated programmer and debugger, requiring no additional hardware. Users can expand

functionality through MIKROE mikroBUS™ Click™ adapter boards, add Ethernet connectivity with the Microchip PHY daughter board, add WiFi connectivity capability using the Microchip expansions boards, and add audio input and output capability with Microchip audio daughter boards. These boards are fully integrated into PIC32’s powerful software framework, MPLAB Harmony,

which provides a flexible and modular interface to application development a rich set of inter-operable software stacks (TCP-IP, USB), and easy-to-use features. The Curiosity PIC32 MZ EF development board offers expansion capabilities making it an excellent choice for a rapid prototyping board in Connectivity, IOT, and general-purpose applications.

Curiosity PIC32MZ EF double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC32

MCU Memory (KB)

2048

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

524288

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 - Oxygen accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
ID COMM
RPD4
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
RPD10
TX
UART RX
RPD15
RX
I2C Clock
RPA14
SCL
I2C Data
RPA15
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

EZO Carrier Click - Oxygen Schematic schematic

Step by step

Project assembly

Curiosity PIC32MZ EF front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity PIC32 MZ EF as your development board.

Curiosity PIC32MZ EF front image hardware assembly
GNSS2 Click front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
Curiosity PIC32 MZ EF MB 1 Access - 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
Curiosity PIC32 MZ EF 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

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 - Oxygen Click driver.

Key functions:

  • ezocarrierdo_send_cmd - Send command function

  • ezocarrierdo_send_cmd_with_par - Send command function with parameter

  • ezocarrierdo_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 DO Click Example.
 *
 * # Description
 * This example demonstrates the use of EZO Carrier DO 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 high point calibration.
 *
 * ## Application Task
 * Reads and processes all incoming dissolved oxygen data from the probe, and displays them on the USB UART in mg/L.
 *
 * ## Additional Function
 * - static void ezocarrierdo_clear_app_buf ( void )
 * - static void ezocarrierdo_log_app_buf ( void )
 * - static err_t ezocarrierdo_process ( ezocarrierdo_t *ctx )
 * - static err_t ezocarrierdo_rsp_check ( ezocarrierdo_t *ctx, uint8_t *rsp )
 * - static void ezocarrierdo_error_check ( err_t error_flag )
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "ezocarrierdo.h"

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

static ezocarrierdo_t ezocarrierdo;
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 DO clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @note None.
 */
static void ezocarrierdo_clear_app_buf ( void );

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

/**
 * @brief EZO Carrier DO data reading function.
 * @details This function reads data from device and concatenates data to application buffer. 
 * @param[in] ctx : Click context object.
 * See #ezocarrierdo_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 ezocarrierdo_process ( ezocarrierdo_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 ezocarrierdo_rsp_check ( ezocarrierdo_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 ezocarrierdo_error_check ( err_t error_flag );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ezocarrierdo_cfg_t ezocarrierdo_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.
    ezocarrierdo_cfg_setup( &ezocarrierdo_cfg );
    EZOCARRIERDO_MAP_MIKROBUS( ezocarrierdo_cfg, MIKROBUS_1 );
    if ( UART_ERROR == ezocarrierdo_init( &ezocarrierdo, &ezocarrierdo_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    log_printf( &logger, "Device status \r\n" );
    ezocarrierdo_send_cmd( &ezocarrierdo, EZOCARRIERDO_CMD_STATUS );
    error_flag = ezocarrierdo_rsp_check( &ezocarrierdo, EZOCARRIERDO_RSP_OK );
    ezocarrierdo_error_check( error_flag );

    log_printf( &logger, "Factory reset \r\n" );
    ezocarrierdo_send_cmd( &ezocarrierdo, EZOCARRIERDO_CMD_FACTORY );
    error_flag = ezocarrierdo_rsp_check( &ezocarrierdo, EZOCARRIERDO_RSP_READY );
    ezocarrierdo_error_check( error_flag );

    log_printf( &logger, "Device info \r\n" );
    ezocarrierdo_send_cmd( &ezocarrierdo, EZOCARRIERDO_CMD_DEV_INFO );
    error_flag = ezocarrierdo_rsp_check( &ezocarrierdo, EZOCARRIERDO_RSP_OK );
    ezocarrierdo_error_check( error_flag );

    uint8_t n_cnt = 0;
    uint8_t last_reading[ APP_BUFFER_SIZE ] = { 0 };
    ezocarrierdo_clear_app_buf( );
    ezocarrierdo_send_cmd( &ezocarrierdo, EZOCARRIERDO_CMD_SINGLE_READ );
    ezocarrierdo_process ( &ezocarrierdo );
    strcpy( last_reading, app_buf );
    log_printf( &logger, "High point calibration \r\n" );
    log_printf( &logger, "Waiting for stable readings \r\n" );
    while ( n_cnt <= 5 )
    {
        if ( EZOCARRIERDO_OK == ezocarrierdo_process ( &ezocarrierdo ) )
        {  
            if ( 0 == strstr( app_buf, last_reading ) )
            {
                n_cnt++;
            }
            else
            {
                strcpy( last_reading, app_buf );
                n_cnt = 0;
            }
        }
        log_printf( &logger, "- " );
        Delay_ms( 1000 );
        ezocarrierdo_clear_app_buf( );
    }
    
    log_printf( &logger, "\r\n Calibration \r\n" );
    ezocarrierdo_send_cmd( &ezocarrierdo, EZOCARRIERDO_CMD_CAL );
    error_flag = ezocarrierdo_rsp_check( &ezocarrierdo, EZOCARRIERDO_RSP_OK );
    ezocarrierdo_error_check( error_flag );

    #define DISABLE_CONT_READ   "0"
    log_printf( &logger, "Disable continuous reading mode \r\n" );
    ezocarrierdo_send_cmd_with_par( &ezocarrierdo, EZOCARRIERDO_CMD_CONT_READ, DISABLE_CONT_READ );
    error_flag = ezocarrierdo_rsp_check( &ezocarrierdo, EZOCARRIERDO_RSP_OK );
    ezocarrierdo_error_check( error_flag );

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

void application_task ( void ) 
{
    log_printf( &logger, "Reading... \r\n" );
    ezocarrierdo_send_cmd( &ezocarrierdo, EZOCARRIERDO_CMD_SINGLE_READ );
    error_flag = ezocarrierdo_rsp_check( &ezocarrierdo, EZOCARRIERDO_RSP_OK );
    ezocarrierdo_error_check( error_flag );
    Delay_ms( 5000 );
}

void main ( void ) 
{
    application_init( );

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

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

static void ezocarrierdo_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 ezocarrierdo_process ( ezocarrierdo_t *ctx ) 
{
    uint8_t rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t overflow_bytes = 0;
    int32_t rx_cnt = 0;
    int32_t rx_size = ezocarrierdo_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 EZOCARRIERDO_OK;
    }
    return EZOCARRIERDO_ERROR;
}

static err_t ezocarrierdo_rsp_check ( ezocarrierdo_t *ctx, uint8_t *rsp )
{
    uint32_t timeout_cnt = 0;
    uint32_t timeout = 10000;
    err_t error_flag = EZOCARRIERDO_OK;
    ezocarrierdo_clear_app_buf( );
    while ( ( 0 == strstr( app_buf, rsp ) ) &&
    ( 0 == strstr( app_buf, EZOCARRIERDO_RSP_ERROR ) ) )
    {
        error_flag |= ezocarrierdo_process( ctx );
        if ( timeout_cnt++ > timeout )
        {
            ezocarrierdo_clear_app_buf( );
            return EZOCARRIERDO_ERROR_TIMEOUT;
        }
        Delay_ms( 1 );
    }
    Delay_ms( 100 );
    error_flag |= ezocarrierdo_process( ctx );
    if ( strstr( app_buf, rsp ) )
    {
        return EZOCARRIERDO_OK;
     }
    else if ( strstr( app_buf, EZOCARRIERDO_RSP_ERROR ) )
    {
        return EZOCARRIERDO_ERROR;
    }
    else
    {
        return EZOCARRIERDO_ERROR;
    }
}

static void ezocarrierdo_error_check ( err_t error_flag )
{
    switch ( error_flag )
    {
        case EZOCARRIERDO_OK:
        {
            ezocarrierdo_log_app_buf( );
            break;
        }
        case EZOCARRIERDO_ERROR:
        {
            log_error( &logger, " Error!" );
            break;
        }
        case EZOCARRIERDO_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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