Scales Kit

SKU:K121

Description

The Scales Kit is an electronic scale kit that uses four sets of half-bridge resistive strain gauges, with a total weighing capacity of up to 200kg. It is paired with a high-precision 24-bit A/D converter chip, the HX711, which features a built-in low-noise programmable amplifier supporting gain adjustments of 32, 64, and 128. When combined with the M5Stack main controller, it allows for the quick and easy construction of an IoT weighing application in just a few minutes.

Note: The Scales Kit requires a weighing panel to function, and the side length of the panel should not exceed 50cm.

Features

Total kit capacity: 200kg
HX711:
- High-precision 24-bit ADC
- Programmable gain amplification: 32, 64, and 128
- 10SPS output data rate
Half-bridge resistive strain gauges:
- Output sensitivity: 1.0±0.1mV/V
- Non-linearity: 0.3%F.S
- Comprehensive accuracy: 0.3%F.S
- Zero-point output: ±0.3mV/V
- Impedance difference between upper and lower strain gauges: 0.8Ω
- Input/output impedance: 1000±5Ω

Includes

4 x Half-Bridge Resistance Strain Gauge
1 x Unit Weight
1 x HY2.0-4P Cable (20cm)
4 x Double-Sided Adhesive Tape (39 x 20 x 0.8mm)
4 x Double-Sided Adhesive Tape (39 x 12 x 0.8mm)
1 x Sensor Wiring Terminal

Applications

Electronic scale design

Specifications

Specification	Parameters
HX711	Output sensitivity: High-precision 24-bit ADC Programmable gain amplification: 32, 64, 128 10SPS output data rate
Half-bridge strain gauges	Output sensitivity: 1.0±0.1mV/V Non-linearity: 0.3%F.S Comprehensive accuracy: 0.3%F.S Zero-point output: ±0.3mV/V Impedance difference: 0.8Ω Input/output impedance: 1000±5Ω
Product Weight	12.7g
Package Size	105.0 x 65.0 x 40.0mm
Gross Weight	133.6g

Schematics

PinMap

Unit Weight

M5Core	G36	G26	5V	GND
Unit Weight	DATA Pin (DAT)	CLOCK Pin (CLK)	VCC	GND

Model Size

Scales Kit_Structure - PDF

Datasheets

HX711

Softwares

Arduino

Calibration Operation

Set the ADC chip GAIN=128, 10SPS output rate, and measure with a 5kg weight. The error is approximately ±1%. Calibration is required before starting to weigh. Refer to the code below for calibration.

#include "HX711.h"

HX711 scale;

void setup() {
    // 1. Set the ADC value at 0g and set it as the offset
    scale.tare();
}

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