Intermediate
30 min

Set the standard for weight accuracy using NAU7802 and ATmega1284P

Weighing made smarter

Load Cell 2 Click with EasyAVR v7

Published Nov 01, 2023

Click board™

Load Cell 2 Click

Dev. board

EasyAVR v7

Compiler

NECTO Studio

MCU

ATmega1284P

Unlock data-driven decisions with precise weight measurements in diverse settings

A

A

Hardware Overview

How does it work?

Load Cell 2 Click is based on the NAU7802, a precision low-power 24-bit analog-to-digital converter (ADC) from Nuvoton, with an onboard low-noise programmable gain amplifier (PGA), onboard RC or Crystal oscillator, and a precision 24-bit sigma-delta (Σ-Δ) analog to digital converter (ADC). The NAU7802 device can perform up to 23-bit ENOB (Effective Number Of Bits). This device provides a complete front-end solution for bridge/sensor measurement, such as in weigh scales, strain gauges, and many other high-resolution, low-sample rate applications. The NAU7802 has many built-in features, which enable high-performance applications with low external

parts count. Additionally, operating current and standby current are low, and many power management features are included. These enable powering only those elements of the chip that are needed and operate at greatly reduced power if the full 23-bit ENOB performance is not required. The Programmable Gain Amplifier (PGA) provides selectable gains from 1 to 128. The A/D conversion is performed with a Sigma-Delta modulator and programmable FIR filter, which provides a simultaneous 50Hz and 60Hz notch filter to improve interference immunity. Also, this device provides a standard 2-wire interface compatible with I2C protocol for simple and straightforward

connection to and interoperation with a wide range of possible host processors. Calibration is not required for low-accuracy applications but may be needed in sensitive applications. When calibration is used, the system designer has three options (details in NAU7802 datasheet). This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Load Cell 2 Click top side image
Load Cell 2 Click bottom side image

Features overview

Development board

EasyAVR v7 is the seventh generation of AVR development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit AVR microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyAVR v7 allows you to connect accessory boards, sensors, and custom electronics more

efficiently than ever. Each part of the EasyAVR v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use a wide range of external power sources, including an external 12V power supply, 7-12V AC or 9-15V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B)

connector. Communication options such as USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets which cover a wide range of 16-bit AVR MCUs. EasyAVR v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

EasyAVR v7 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Architecture

AVR

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

16384

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Data Ready
PD2
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PC0
SCL
I2C Data
PC1
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Load Cell 2 Click Schematic schematic

Step by step

Project assembly

EasyAVR v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyAVR v7 as your development board.

EasyAVR v7 front image hardware assembly
GNSS2 Click front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
EasyAVR v7 Access DIP 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 Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto DIP image step 7 hardware assembly
EasyPIC PRO v7a Display Selection Necto Step hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image 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 Load Cell 2 Click driver.

Key functions:

  • loadcell2_get_weight - Get weight function

  • loadcell2_get_result - Get results function

  • loadcell2_calibration - Calibration function

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 
 * \brief LoadCell2 Click example
 * 
 * # Description
 * Load Cell 2 click is a weight measurement click 
 * which utilizes a load cell element, 
 * in order to precisely measure the weight of an object. 
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes I2C driver and performs the device reset, 
 * and performs the device reset, set power on and default configuration.
 * Sets tare the scale, calibrate scale and start measurements.
 * 
 * ## Application Task  
 * This is an example which demonstrates the 
 * use of Load Cell 2 Click board. 
 * Display the measurement of scales in grams [g].
 * Results are being sent to the Usart Terminal 
 * where you can track their changes.
 * All data logs write on USB uart changes for every 1 sec.
 * 
 * \author Nenad Filipovic
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "loadcell2.h"

// ------------------------------------------------------------------ VARIABLES

static loadcell2_t loadcell2;
static log_t logger;

static loadcell2_data_t cell_data;
static float weight_val;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
{
    log_cfg_t log_cfg;
    loadcell2_cfg_t cfg;

    /** 
     * 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.

    loadcell2_cfg_setup( &cfg );
    LOADCELL2_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    loadcell2_init( &loadcell2, &cfg );
    
    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "     Load cell click     \r\n");
    log_printf( &logger, "-------------------------\r\n");
    Delay_ms( 100 );
    
    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "   Reset all registers   \r\n");
    loadcell2_reset( &loadcell2 );
    Delay_ms( 100 );
    
    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "        Power On         \r\n");
    loadcell2_power_on( &loadcell2 );
    Delay_ms( 100 );

    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "   Set default config.   \r\n");
    loadcell2_default_cfg( &loadcell2 );
    Delay_ms( 100 );

    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "      Calibrate AFE      \r\n");
    loadcell2_calibrate_afe( &loadcell2 );
    Delay_ms( 1000 );

    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "     Tare the scale :    \r\n");
    log_printf( &logger, "- - - - - - - - - - - - -\r\n");
    log_printf( &logger, " >> Remove all object << \r\n");
    log_printf( &logger, "- - - - - - - - - - - - -\r\n");
    log_printf( &logger, " In the following 10 sec \r\n");
    log_printf( &logger, " please remove all object\r\n");
    log_printf( &logger, "     from the scale.     \r\n");
    Delay_ms( 10000 );

    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "    Start tare scales    \r\n");
    loadcell2_tare ( &loadcell2, &cell_data );
    Delay_ms( 500 );

    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "   Tarring is complete   \r\n");
    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "    Calibrate Scale :    \r\n");
    log_printf( &logger, "- - - - - - - - - - - - -\r\n");
    log_printf( &logger, "   >>> Load etalon <<<   \r\n");
    log_printf( &logger, "- - - - - - - - - - - - -\r\n");
    log_printf( &logger, " In the following 10 sec \r\n");
    log_printf( &logger, "place 1000g weight etalon\r\n");
    log_printf( &logger, "    on the scale for     \r\n");
    log_printf( &logger, "   calibration purpose.  \r\n");
    Delay_ms( 10000 );

    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "    Start calibration    \r\n");

    if ( loadcell2_calibration ( &loadcell2, LOADCELL2_WEIGHT_1000G, &cell_data ) == LOADCELL2_GET_RESULT_OK )
    {
        log_printf( &logger, "-------------------------\r\n");
        log_printf( &logger, "    Calibration  Done    \r\n");

        log_printf( &logger, "- - - - - - - - - - - - -\r\n");
        log_printf( &logger, "  >>> Remove etalon <<<  \r\n");
        log_printf( &logger, "- - - - - - - - - - - - -\r\n");
        log_printf( &logger, " In the following 10 sec \r\n");
        log_printf( &logger, "   remove 1000g weight   \r\n");
        log_printf( &logger, "   etalon on the scale.  \r\n");
        Delay_ms( 10000 );
    }
    else
    {
        log_printf( &logger, "-------------------------\r\n");
        log_printf( &logger, "   Calibration  Error   \r\n");
        for ( ; ; );
    }

    log_printf( &logger, "-------------------------\r\n");
    log_printf( &logger, "   Start measurements :  \r\n");
    log_printf( &logger, "-------------------------\r\n");
}

void application_task ( void )
{
    weight_val = loadcell2_get_weight( &loadcell2, &cell_data );

    log_printf(&logger, "   Weight : %.2f g\r\n", weight_val );

    Delay_ms( 1000 );
}

void main ( void )
{
    application_init( );

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


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

Additional Support

Resources

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