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I wanna create my own HX711 Module for scale (weigh). How to do that and what to...
quaeke

quaeke

@copilot I wanna create my own HX711 Module for scale (weigh). How to do that and what to do exact?
2y

copilot

Creating your own HX711 module for a scale involves designing a circuit that interfaces the HX711 chip with a load cell (for weight detection) and a microcontroller (for data processing and communication). The HX711 chip is a precision 24-bit analog-to-digital converter (ADC) specifically designed for weigh scales and industrial control applications to interface directly with a bridge sensor. Here's a step-by-step guide to designing your HX711 module:
  1. Power Supply Connections:
    • The HX711 requires two supply voltages: one for the analog circuitry (AVDD) and one for the digital circuitry (DVDD). AVDD can be between 2.6V and 5.5V, and DVDD can be between 2.7V and 5.5V. A common approach is to use a single 5V supply for both AVDD and DVDD.
      • Connect U1:VSUP and U1:AVDD to your 5V supply.
      • Connect U1:DVDD to your 5V supply.
      • Connect U1:AGND and U1:BASE to ground.
  2. Load Cell Connections:
    • The load cell, which is a type of bridge sensor, should be connected to the HX711's INA+ and INA− pins for one pair of the bridge outputs, and the other pair should be connected to the supply voltage and ground accordingly. If you have a second bridge sensor, it can be connected to INB+ and INB−.
      • Assuming a single load cell, connect the load cell's positive output to U1:INA+ and the negative output to U1:INA-.
  3. Digital Connections for Data Retrieval:
    • The PD_SCK and DOUT pins are used to communicate with a microcontroller or another digital interface.
      • Connect U1:PD_SCK to a digital output pin on your microcontroller for providing the clock signal.
      • Connect U1:DOUT to a digital input pin on your microcontroller for reading the data.
  4. Other Connections:
    • U1:XO and U1:XI: Typically, these pins are connected to an external oscillator for the HX711's clock. However, it's common to leave these disconnected as the HX711 has an internal oscillator which is sufficient for most applications.
    • U1:RATE: This pin is used to set the output data rate. Connect it to DVDD for 10SPS (samples per second) or leave it unconnected for 80SPS.
    • U1:VBG, U1:VFB: These are typically not used for basic applications and can be left unconnected.
  5. Common Tips:
    • Use decoupling capacitors near the power supply pins to reduce noise.
    • Keep the analog and digital ground planes separate and connect them at a single point to reduce interference.
    • Pay attention to the PCB layout to minimize noise and ensure accurate measurements, especially around the INA+/INA− pins.
Here's a simplified connection guide based on the steps above:
  • Connect U1:VSUP, U1:AVDD, and U1:DVDD to your 5V supply.
  • Connect U1:AGND and U1:BASE to ground.
  • Connect your load cell's positive output to U1:INA+ and the negative output to U1:INA-.
  • Connect U1:PD_SCK to a microcontroller digital output.
  • Connect U1:DOUT to a microcontroller digital input.
  • Leave U1:XO and U1:XI unconnected for using the internal oscillator.
  • Connect U1:RATE to DVDD for a 10 SPS rate or leave it unconnected for 80 SPS.
I've made assumptions regarding the supply voltage and single load cell use. If these assumptions don't match your requirements, please adjust accordingly. Let me know if you need details on the microcontroller side or have specific parameters for adjustments!
2y
quaeke

quaeke

I wanna to integrate HX711 to my ESP32 custom board. There I have just a supply of 3.3 V
2y

copilot

Integrating the HX711 ADC chip with an ESP32-based custom board using a 3.3V supply requires adjusting the connections to accommodate the lower voltage level. Fortunately, the HX711 can operate with a supply voltage as low as 2.6V for its analog part (AVDD) and 2.7V for its digital part (DVDD), so it's compatible with your 3.3V supply. Here's how to proceed:
Power Supply Connections:
  • Since your supply is 3.3V, you'll use this for both the analog (AVDD) and digital (DVDD) sections of the HX711.
    • Connect U1:VSUP and U1:AVDD to the 3.3V supply.
    • Connect U1:DVDD to the 3.3V supply.
    • Connect U1:AGND and U1:BASE to the ground.
Load Cell Connections:
  • The connection strategy for the load cell remains unchanged. Just ensure the load cell operates correctly at the given voltage level.
    • Connect the load cell's positive output to U1:INA+ and the negative output to U1:INA-.
Digital Connections for Data Retrieval with ESP32:
  • The ESP32 I/O pins are typically 3.3V tolerant, which matches the operating voltage of the HX711.
    • Connect U1:PD_SCK to an ESP32 GPIO configured as an output (for the clock signal).
    • Connect U1:DOUT to an ESP32 GPIO configured as an input (for reading data).
Other Connections:
  • U1:XO and U1:XI: Leave these disconnected to use HX711's internal oscillator.
  • U1:RATE: Connection depends on your desired rate; connect it to DVDD (3.3V in your case) for 10SPS or leave it unconnected for an 80SPS rate.
  • U1:VBG, U1:VFB: These remain typically not connected for basic operations.
Considerations:
  • Ensure to include decoupling capacitors close to the HX711 power supply pins to reduce power supply noise. A combination of a 0.1µF ceramic capacitor and a 10µF electrolytic or tantalum capacitor is commonly used.
  • Keep the ESP32 and any digital circuitry physically and electrically distanced from the HX711 and load cell connections to minimize noise interference in the analog signals.
  • Remember that changing the supply voltage might slightly affect the HX711's performance, so it's recommended to calibrate your scale after assembly.
Here's a concise integration guide considering your 3.3V scenario:
  • Connect U1:VSUP, U1:AVDD, and U1:DVDD to your 3.3V supply.
  • Connect U1:AGND and U1:BASE to ground.
  • Connect your load cell output to U1:INA+ (positive) and U1:INA- (negative).
  • Connect U1:PD_SCK to an ESP32 GPIO as an output.
  • Connect U1:DOUT to another ESP32 GPIO as an input.
  • Optional: Connect U1:RATE to 3.3V for 10 SPS or leave it to attain an 80 SPS data rate.
This setup should get your HX711 module integrated with the ESP32 customized for operation at 3.3V. If you run into issues or have specific needs regarding the ESP32 programming or additional functionalities, feel free to ask!
2y
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