How to Solve HX711's Low Output Voltage Problem

How to Solve HX711 's Low Output Voltage Problem

How to Solve HX711 's Low Output Voltage Problem: Causes and Solutions

The HX711 is a popular 24-bit analog-to-digital converter (ADC) commonly used in weighing scales and other measurement systems that require precise weight data. However, sometimes users encounter a low output voltage issue when working with the HX711 , leading to incorrect readings or malfunctioning systems. Let's break down the causes of this issue and provide a step-by-step guide on how to fix it.

Causes of HX711's Low Output Voltage Problem

The low output voltage problem from the HX711 can be caused by several factors. These include:

Power Supply Issues: If the power supply is unstable or provides insufficient voltage, the HX711 won't function properly, leading to low output voltage. The HX711 typically requires a 5V power supply. Any fluctuations or insufficient voltage can affect the readings. Incorrect Load Cell Wiring: The HX711 connects to a load cell, and if the load cell is improperly wired or has a poor connection, the output signal from the load cell could be weak or not transmitted properly to the HX711. Poor Grounding or Noise: Grounding issues or electrical noise in the system can result in unstable or low voltage readings. This can happen if the ground connections are improperly established or if the environment is electrically noisy. Faulty or Low-Quality Load Cell: If the load cell is defective or of low quality, it might not provide a strong enough signal to generate the correct output. This can result in low output voltage from the HX711. Incorrect Gain Setting: The HX711 provides different gain options for signal amplification. If the gain is set incorrectly, the output signal might be too low or too high, affecting accuracy. Insufficient Amplification: The HX711 uses a built-in amplifier to boost the small signals from the load cell. If the amplifier is not functioning correctly or is overloaded, the output voltage can be too low to interpret accurately.

How to Solve the Low Output Voltage Problem

Step 1: Check the Power Supply Ensure stable 5V supply: Confirm that the HX711 is receiving a stable 5V power input. You can measure the voltage using a multimeter. If the voltage is fluctuating or insufficient, use a more reliable power source. Filter power supply: If you suspect electrical noise, add decoupling capacitor s (typically 100nF) near the power pins of the HX711 to filter out noise. Step 2: Verify Load Cell Wiring

Double-check the connections: Make sure the load cell is correctly connected to the HX711. The typical wiring configuration for a 4-wire load cell should be:

Red to E+ (Excitation Positive)

Black to E- (Excitation Negative)

White to A- (Signal Negative)

Green to A+ (Signal Positive)

Any loose or broken wires could lead to weak or no output.

Step 3: Inspect Grounding and Noise Reduction Proper grounding: Ensure that the HX711 and the load cell share a common ground. A floating ground or improper grounding can introduce noise, which causes the signal to fluctuate. Minimize noise: Keep the HX711 and load cell wires away from high-power lines or sources of electrical noise. If needed, shield the wires with grounded copper tape or use twisted-pair wires to reduce noise interference. Step 4: Test the Load Cell Test the load cell separately: If possible, test the load cell with a different ADC or multimeter to ensure it's functioning properly. If the load cell is defective, replacing it will be necessary. Step 5: Adjust Gain Settings Modify the gain: The HX711 has three possible gain settings: 128, 64, and 32. The default gain is typically 128. If the output signal is too weak, increasing the gain can help boost the signal. Check the datasheet or your microcontroller code to make sure the gain is set appropriately for your application. Step 6: Ensure Proper Amplification Verify amplifier functionality: If you still experience low output voltage despite the above steps, the internal amplifier of the HX711 might not be functioning as expected. In such cases, consider replacing the HX711 with a new one. Step 7: Calibration Perform calibration: After addressing the hardware issues, calibrate your system by adjusting the offset and scale factors in your software. This will help correct any discrepancies in the output readings.

Conclusion

Low output voltage in the HX711 can stem from various issues, including power supply problems, incorrect wiring, poor grounding, defective components, and improper configuration. By following the steps outlined above — from checking the power supply to adjusting the gain settings — you can troubleshoot and resolve the problem. In many cases, careful inspection and calibration of both the hardware and software will restore proper function to your HX711 setup.