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CONTENTS

Scales Kit

SKU:K121

Description

Scales Kit is a high precision low-cost weighing kit. This digital Scales kit is consist of four pieces of half-bridge resistive strain gauges, with a total weighing range of 200kgs. It is equipped with a 24-bit A/D converter chip HX711, specially designed for the high precision electronic scale. The built-in low-noise programmable amplifier supports 32/64/128 times gain adjustment. With the help of M5Stack core for programming, you can create IoT based Weighing Scale in just a few minutes!

NOTE: The Scale Kit will need a cover plate to work with, and the size of the cover plate should not exceed 50cm on one side.

Features

  • Total weighing range of 200kgs
  • HX711:
    • High precision 24bit ADC
    • Programmable gain amplification 32, 64 and 128
    • 10SPS output data rate
  • Half-bridge resistive strain gauge.
    • Output sensitivity: 1.0±0.1mV/V
    • Non-linearity: 0.3% F.S
    • Integrated Accuracy: 0.3%F.S
    • Zero output: ±0.3mv/V
    • Difference between upper and lower impedance of each strain gauge: 0.8Ω
    • Output (in) impedance: 1000±5Ω
  • Development platform:

Included

  • 4x Half-bridge resistive strain gauge
  • 1x WEIGHT UNIT
  • 1x HY2.0-4P Cable (20cm)
  • 4x Double-sided adhesive paper (39 * 20 * 0.8mm)
  • 4x Double-sided adhesive paper (39 * 12 * 0.8mm)

Applications

  • Electronic weighing

Installation Diagram

Specifications

Specifications Parameters
HX711 Output Sensitivity: High Precision 24bit ADC
Programmable Gain Amplification 32, 64, 128
10SPS Output Data Rate
Half-Bridge Resistance Strain Gauge Output Sensitivity: 1.0±0.1mV/V
Nonlinearity: 0.3%FS
Comprehensive Accuracy: 0.3%FS
Zero Output: ±0.3mv/V
Each The difference between the upper and lower impedance of the gauge strain gauge: 0.8Ω
Output (input) impedance: 1000±5Ω
Gross Weight 92.5g
Net Weight 126.3g
Packing Size 105mm x 65mm x 40mm

PinMap

  • WEIGHT UNIT
M5CORE - PORT B G36 G26 5V GND
WEIGHT UNIT DATA Pin (DAT) CLOCK Pin (CLK) VCC GND

Schematic

  • WEIGHT UNIT

offsets/calibration

Set the ADC chip GAIN=128, 10SPS output rate, under the condition of 5kg weight measurement, the error is about ±1%. Calibration is required before starting weighing, please refer to the code below for operation.

#include "HX711.h"

HX711 scale;

void setup() {
     // 1. Set the ADC value in the case of 0g and set it to offset
     scale.tare();
}

void loop() {
     // 2. Read the average value of ADC in the case of standard weight (such as 5kg)
     long kg_adc = scale.read_average(20);
     // 3. Read the offset in the current 0g case
     kg_adc = kg_adc - scale.get_offset();
     // 4. Calculate and configure the scale parameter
     scale.set_scale( kg_adc / (5 * 1000.0));
}

Example

Arduino