Enable fair and reliable trade through dependable weight measurements.
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Hardware Overview
How does it work?
Load Cell 3 Click is based on the PGA302, a high accuracy, low drift, low noise, low power, and versatile signal conditioner automotive grade-qualified device for resistive bridge pressure and temperature-sensing applications from Texas Instruments. The PGA302 provides bridge excitation voltages of 2.5V. The PGA302 conditions sensing and temperature signals by amplifying and digitizing through the analog front-end chain and performing linearization and temperature compensation. The conditioned signals can be output in analog form, and besides that, the signal data can be accessed by an I2C digital interface. The PGA302 contains two separated analog-front
end (AFE) chains with their gain amplifiers for resistive bridge and temperature sensing inputs. The resistive bridge input AFE chain consists of a programmable gain with eight steps from 1.33V/V to 200V/V. For the temperature-sensing input AFE chain, the PGA302 provides a current source of up to 1mA for the optional external temperature sensing available on the onboard terminal labeled with TMP+ and TMP-. After the ADC decimation filters, the digitalized signals are sent to the linearization and compensation calculation digital signal logic. All required parameters for the linearization algorithm and other user data are stored in the integrated EEPROM memory.
At the device's output, a 14-bit DAC is followed by a ratiometric-voltage supply output buffer with a gain of 4 V/V, allowing a 0-5V ratiometric voltage system output available on the AN pin on the mikroBUS™ socket. This Click board™ can be operated only with a 5V 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.
Features overview
Development board
Nucleo-144 with STM32F413ZH MCU board offers an accessible and adaptable avenue for users to explore new ideas and construct prototypes. It allows users to tailor their experience by selecting from a range of performance and power consumption features offered by the STM32 microcontroller. With compatible boards, the
internal or external SMPS dramatically decreases power usage in Run mode. Including the ST Zio connector, expanding ARDUINO Uno V3 connectivity, and ST morpho headers facilitate easy expansion of the Nucleo open development platform. The integrated ST-LINK debugger/programmer enhances convenience by
eliminating the need for a separate probe. Moreover, the board is accompanied by comprehensive free software libraries and examples within the STM32Cube MCU Package, further enhancing its utility and value.
Microcontroller Overview
MCU Card / MCU

Architecture
ARM Cortex-M4
MCU Memory (KB)
1536
Silicon Vendor
STMicroelectronics
Pin count
144
RAM (Bytes)
327680
You complete me!
Accessories
Click Shield for Nucleo-144 comes equipped with four mikroBUS™ sockets, with one in the form of a Shuttle connector, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-144 board with no effort. This way, MIKROE allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. Featuring an ARM Cortex-M microcontroller, 144 pins, and Arduino™ compatibility, the STM32 Nucleo-144 board offers limitless possibilities for prototyping and creating diverse applications. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-144 board out of the box, with an additional USB cable connected to the USB mini port on the board. Simplify your project development with the integrated ST-Link debugger and unleash creativity using the extensive I/O options and expansion capabilities. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the STM32 Nucleo-144 board with our Click Shield for Nucleo-144, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic

Step by step
Project 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 3 Click driver.
Key functions:
loadcell3_tare
- Load Cell 3 tare the scales functionloadcell3_calibration
- Load Cell 3 calibration functionloadcell3_get_weight
- Load Cell 3 get weight 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 main.c
* @brief LoadCell3 Click example
*
* # Description
* This library contains API for the Load Cell 3 Click driver.
* The library also includes a function for tare and calibration and weight measurement.
* This demo application shows an example of weight measurement.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialization of I2C module and log UART.
* After driver initialization and default settings, the app sets tare the scale,
* calibrate scale and start measurements.
*
* ## Application Task
* This is an example that shows the use of a Load Cell 3 Click board™.
* The Load Cell 3 Click board can be used to measure weight,
* shows the measurement of scales in grams [ g ].
* Results are being sent to the Usart Terminal where you can track their changes.
*
* @author Nenad Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "loadcell3.h"
static loadcell3_t loadcell3;
static log_t logger;
static loadcell3_data_t cell_data;
static float weight_val;
void application_init ( void ) {
log_cfg_t log_cfg; /**< Logger config object. */
loadcell3_cfg_t loadcell3_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.
loadcell3_cfg_setup( &loadcell3_cfg );
LOADCELL3_MAP_MIKROBUS( loadcell3_cfg, MIKROBUS_1 );
err_t init_flag = loadcell3_init( &loadcell3, &loadcell3_cfg );
if ( init_flag == I2C_MASTER_ERROR ) {
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
loadcell3_default_cfg ( &loadcell3 );
log_info( &logger, " Application Task " );
Delay_ms ( 100 );
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" );
// 10 seconds delay
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
log_printf( &logger, "-------------------------\r\n" );
log_printf( &logger, " Start tare scales \r\n" );
loadcell3_tare ( &loadcell3, &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 100g weight etalon \r\n" );
log_printf( &logger, " on the scale for \r\n" );
log_printf( &logger, " calibration purpose. \r\n" );
// 10 seconds delay
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
log_printf( &logger, "-------------------------\r\n" );
log_printf( &logger, " Start calibration \r\n" );
if ( loadcell3_calibration ( &loadcell3, LOADCELL3_WEIGHT_100G, &cell_data ) == LOADCELL3_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 100g weight \r\n" );
log_printf( &logger, " etalon on the scale. \r\n" );
// 10 seconds delay
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
}
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 = loadcell3_get_weight( &loadcell3, &cell_data );
log_printf( &logger, " Weight : %.2f g\r\n", weight_val );
Delay_ms ( 1000 );
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END