Load Cell 3 Click Board™

Product Code: MIKROE-4658

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 Type Force Applications Can be used for weight scale and force-sensing applications that use strain gauge load cells and other general resistive bridge signal-conditioning applications. On-board modules PGA302 - a programmable signal-conditioner device designed for various resistive bridge-sensing applications from Texas Instruments Key Features Dual-channel analogue front-end, 16-bit Sigma-Delta ADC, programmable gain up to 200V/V, on-chip temperature sensor, EEPROM memory for device configuration, calibration and user data, and more. Interface Analog, I2C Compatibility mikroBUS Click board size M (42.9 x 25.4 mm) Input Voltage 5V 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 Label Name Default Description LD1 PWR - Power LED Indicator LOAD CELL 3 CLICK ELECTRICAL SPECIFICATIONS Description Min Typ Max Unit Supply Voltage - 5 - V ADC Resolution - 16 - bits Operating Temperature Range -40 +25 +150 °C