Mikroelektronika d.o.o.
Load Cell 2 Click Board
Load Cell 2 Click Board
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Overview
The Load Cell 2 Click Board™ is a weight measurement click that utilizes a load cell element, in order to precisely measure the weight of an object. The Load Cell 2 Click can be used with the strain gauge type of load cells with external differential reference voltage range from 0.1V to 5V. The strain gauge load cell is typically a circuit made of four strain gauges, connected in the Wheatstone bridge configuration. Very small voltage changes need to be accurately detected and converted into a digital form. The Load Cell 2 Click is based around the NAU7802, which is a 24-bit analog-to-digital converter, operated via a simple I2C command, from Nuvoton. This sensor has many features that make it a perfect solution for small designs. One of these features is certainly its high level of integration that allows a minimal number of external components.
The Load Cell 2 Click Board™ is supported by a mikroSDK compliant library, which includes functions that simplify software development. This Click Board™ comes as a fully tested product, ready to be used on a system equipped with the mikroBUS™ socket.
How Does The Load Cell 2 Click Board™ Work?
The Load Cell 2 Click Board™ is based on the NAU7802 is a precision low-power 24-bit analog-to-digital converter (ADC), 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 is capable of up to 23-bit ENOB (Effective Number Of Bits) performance. 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 have many built-in features, which enable high performance applications with very low external parts count. Additionally, both operating current and standby current are very low, and many power management features are included. These enable powering only those elements of the chip that are needed, and also, to 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 that provides a simultaneous 50Hz and 60Hz notch filter to effectively 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).
The power supply is 3.3V and this allows only 3.3V MCUs to be interfaced with the Click boards™ directly.
SPECIFICATIONS
| Type | Force |
| Applications | NAU7802 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. |
| On-board modules | NAU7802 24-Bit Dual-Channel ADC For Bridge Sensors |
| Key Features | NAU7802 is a precision low-power 24-bit analog-to-digital converter (ADC), 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) |
| Interface | I2C |
| Compatibility | mikroBUS |
| Click board size | S (28.6 x 25.4 mm) |
| Input Voltage | 3.3V |
PINOUT DIAGRAM
This table shows how the pinout of the Load Cell 2 Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).
| Notes | Pin |  |
Pin | Notes | |||
|---|---|---|---|---|---|---|---|
| NC | 1 | AN | PWM | 16 | NC | ||
| NC | 2 | RST | INT | 15 | RDY | Data Ready | |
| NC | 3 | CS | RX | 14 | NC | ||
| NC | 4 | SCK | TX | 13 | NC | ||
| NC | 5 | MISO | SCL | 12 | SCL | I2C Clock | |
| NC | 6 | MOSI | SDA | 11 | SDA | I2C Data | |
| Power Supply | 3.3V | 7 | 3.3V | 5V | 10 | NC | |
| Ground | GND | 8 | GND | GND | 9 | GND | Ground |
ONBOARD SETTINGS AND INDICATORS
| Label | Name | Default | Description |
|---|---|---|---|
| LD1 | PWR | - | Power LED Indicator |
Software Support
We provide a library for the Load Cell 2 Click Board™ on our LibStock page, as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.
Library Description
The library covers all the necessary functions to control the Load Cell 2 Click Board™. Library performs a standard I2C interface communication.
Key Functions
float loadcell2_get_weight ( loadcell2_data_t *cell_data )- Get weight function.uint32_t loadcell2_get_result ( void )- Get results function.void loadcell2_set_default_config ( void )- Set default sensor configuration function.
Example Description
The application is composed of three sections :
- System Initialization - Initializes I2C, set INT pin as input and stert to write log.
- Application Initialization - Initializes I2C driver and performs the device reset, set power on and default configuration. Sets tare the scale, calibrate scale and start measurements.
- Application Task - (code snippet) - This is an example which demonstrates the use of the 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.
void application_task ( )
{
weight_val = loadcell2_get_weight( &cell_data );
log_display( weight_val );
Delay_ms( 1000 );
}
Additional Functions :
void log_display ( float display_val )- Function displays readings as floating point value with two decimal places.
The full application code, and ready to use projects can be found on our LibStock page.
Other mikroE Libraries used in the example:
- I2C
- UART
- Conversions
Additional Notes and Information
Depending on the development board you are using, you may need a USB UART click, USB UART 2 click or RS232 click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.
MIKROSDK
The Load Cell 2 Click Board™ is supported with mikroSDK - MikroElektronika Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.
Software Support
We provide a library for the Load Cell 2 Click Board™ on our LibStock page, as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.
Library Description
The library covers all the necessary functions to control the Load Cell 2 Click Board™. Library performs a standard I2C interface communication.
Key Functions
float loadcell2_get_weight ( loadcell2_data_t *cell_data )- Get weight function.uint32_t loadcell2_get_result ( void )- Get results function.void loadcell2_set_default_config ( void )- Set default sensor configuration function.
Example Description
The application is composed of three sections :
- System Initialization - Initializes I2C, set INT pin as input and stert to write log.
- Application Initialization - Initializes I2C driver and performs the device reset, set power on and default configuration. Sets tare the scale, calibrate scale and start measurements.
- Application Task - (code snippet) - This is an example which demonstrates the use of the 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.
void application_task ( )
{
weight_val = loadcell2_get_weight( &cell_data );
log_display( weight_val );
Delay_ms( 1000 );
}
Additional Functions :
void log_display ( float display_val )- Function displays readings as floating point value with two decimal places.
The full application code, and ready to use projects can be found on our LibStock page.
Other mikroE Libraries used in the example:
- I2C
- UART
- Conversions
Additional Notes and Information
Depending on the development board you are using, you may need a USB UART click, USB UART 2 click or RS232 click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.
MIKROSDK
The Load Cell 2 Click Board™ is supported with mikroSDK - MikroElektronika Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.
Frequently Asked Questions
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