Load Cell 3 Click Board

Product Description

How Does the Load Cell 3 Click Board™ Work?

The Load Cell 3 Click Board™ as its foundation uses 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 analogue front end chain and performing linearization and temperature compensation. The conditioned signals can be output in analogue form, and, besides that, the signal data can be accessed by an I2C digital interface.

The PGA302 contains two separated analogue-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 that can source up to 1mA for the optional external temperature sensing available on the on-board terminal labelled 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.

The Load Cell 3 Click Board™ operates only with a 5V logic voltage level. The board must perform appropriate logic voltage level conversion before use with MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

SPECIFICATIONS

PINOUT DIAGRAM

This table shows how the pinout on Load Cell 3 Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Analog Signal	AN	1	AN	PWM	16	NC
NC	2	RST	INT	15	NC
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
NC	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

ONBOARD SETTINGS AND INDICATORS

LOAD CELL 3 CLICK ELECTRICAL SPECIFICATIONS

Software Support

void application_task ( void ) {
 weight_val = loadcell3_get_weight( &loadcell3, &cell_data );
 log_printf( &logger, " Weight : %.2f grn", weight_val );
 Delay_ms( 1000 );
}

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