Circuit Documentation

Summary

This circuit is designed to interface a load cell with an ESP32 microcontroller using an HX711 bridge sensor interface. Additionally, it includes an ENS160+AHT21 sensor for environmental monitoring (temperature and humidity). The circuit is powered by a 12V power supply, which is stepped down to 3.3V using a Mini-360 DC-DC Step Down Buck Converter.

Component List

1. Load Cell - Red/white/black/green

   • Description: A load cell used for measuring weight.
   • Pins: E+, A-, E-, A+

2. HX711 - Bridge Sensor Interface

   • Description: An interface for bridge sensors like load cells.
   • Pins: E+, E-, A-, A+, B-, B+, GND - GROUND, DATA (OUT), SCK - CLOCK (IN), 3.3/3.5V Supply

3. ESP32

   • Description: A microcontroller with Wi-Fi and Bluetooth capabilities.
   • Pins: EN, VP, VN, D34, D35, D32, D33, D25, D26, D27, D14, D12, D13, GND, VIN, 3V3, D15, D2, D4, RX2, TX2, D5, D18, D19, D21, RX0, TX0, D22, D23, BOOT

4. ENS160+AHT21

   • Description: A sensor module for environmental monitoring (temperature and humidity).
   • Pins: VIN, 3V3, GND, SCL, SDA, ADD, CS, INT

5. Mini-360 DC-DC Step Down Buck Converter

   • Description: A DC-DC converter to step down voltage from 12V to 3.3V.
   • Pins: Input -, Input +, Output +, Output -

6. 12V Power Supply

   • Description: A power supply providing 12V DC.
   • Pins: +, -

Wiring Details

Load Cell - Red/white/black/green

• E+ connected to E+ of HX711
• A- connected to A- of HX711
• E- connected to E- of HX711
• A+ connected to A+ of HX711

HX711 - Bridge Sensor Interface

• E+ connected to E+ of Load Cell
• A- connected to A- of Load Cell
• E- connected to E- of Load Cell
• A+ connected to A+ of Load Cell
• GND - GROUND connected to GND of ENS160+AHT21 and Output - of Mini-360 DC-DC Step Down Buck Converter
• DATA (OUT) connected to D12 of ESP32
• SCK - CLOCK (IN) connected to D13 of ESP32
• 3.3/3.5V Supply connected to 3V3 of ENS160+AHT21 and Output + of Mini-360 DC-DC Step Down Buck Converter

ESP32

• D12 connected to DATA (OUT) of HX711
• D13 connected to SCK - CLOCK (IN) of HX711
• D21 connected to SDA of ENS160+AHT21
• D22 connected to SCL of ENS160+AHT21

ENS160+AHT21

• GND connected to GND - GROUND of HX711 and Output - of Mini-360 DC-DC Step Down Buck Converter
• 3V3 connected to 3.3/3.5V Supply of HX711 and Output + of Mini-360 DC-DC Step Down Buck Converter
• SDA connected to D21 of ESP32
• SCL connected to D22 of ESP32

Mini-360 DC-DC Step Down Buck Converter

• Input - connected to - of 12V Power Supply
• Input + connected to + of 12V Power Supply
• Output - connected to GND - GROUND of HX711 and GND of ENS160+AHT21
• Output + connected to 3.3/3.5V Supply of HX711 and 3V3 of ENS160+AHT21

12V Power Supply

• - connected to Input - of Mini-360 DC-DC Step Down Buck Converter
• + connected to Input + of Mini-360 DC-DC Step Down Buck Converter

Code Documentation

#include <HX711.h>
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_AHTX0.h>

// HX711 pins
#define HX711_DOUT 12
#define HX711_SCK 13

// I2C pins for ENS160+AHT21
#define I2C_SDA 21
#define I2C_SCL 22

// Create instances
HX711 scale;
Adafruit_AHTX0 aht;

void setup() {
  // Initialize Serial Monitor
  Serial.begin(115200);
  
  // Initialize HX711
  scale.begin(HX711_DOUT, HX711_SCK);
  Serial.println("HX711 initialized.");

  // Initialize I2C for ENS160+AHT21
  Wire.begin(I2C_SDA, I2C_SCL);
  if (!aht.begin()) {
    Serial.println("Failed to find AHT sensor!");
    while (1) delay(10);
  }
  Serial.println("AHT sensor initialized.");
}

void loop() {
  // Read weight from HX711
  if (scale.is_ready()) {
    long reading = scale.read();
    Serial.print("HX711 reading: ");
    Serial.println(reading);
  } else {
    Serial.println("HX711 not found.");
  }

  // Read temperature and humidity from AHT21
  sensors_event_t humidity, temp;
  aht.getEvent(&humidity, &temp);
  Serial.print("Temperature: ");
  Serial.print(temp.temperature);
  Serial.println(" degrees C");
  Serial.print("Humidity: ");
  Serial.print(humidity.relative_humidity);
  Serial.println("% rH");

  // Delay between readings
  delay(2000);
}

This code initializes the HX711 and ENS160+AHT21 sensors, reads data from them, and prints the readings to the Serial Monitor. The HX711 is used to read weight data from the load cell, while the ENS160+AHT21 is used to read temperature and humidity data.