Digital Display Control Board for HC-SR04 Ultrasonic Sensor - Rangefinder Module

Specifications

• Compatibility: Designed for HC-SR04 (and compatible 4-pin) Ultrasonic Sensors.

• Operating Voltage: 5V DC.

• Measurement Range: 3cm – 400cm.

• Display Unit: Centimeters (cm).

• Display Type: 3-Digit 0.36" Red LED .

• Controller: STM8S103 High-Performance MCU.

• Output Interfaces:

  • Display: Direct visual readout.

  • Serial (TTL): TX/RX pins available to send data to another microcontroller (9600 baud).

• Dimensions: 24mm x 20mm (Compact).

Compatibility & Platform Support

• Standalone Mode: Works Independently. Just add 5V power. No Arduino needed.

• Arduino / ESP32: Compatible. You can read the distance via the Serial (TX) pin if you want to log data while still having a visual display.

Key Applications & Projects

• Garage Parking Assistant: Mount this on the wall; the display shows exactly how close your car bumper is.

• Water Level Monitor: Install at the top of a tank to see the air gap (distance to water) in cm.

• Robot "Eyes": Give your mobile robot a diagnostic face that shows what it sees in real-time.

• Education Tool: Teach physics students about sound waves and distance without complex wiring.

Virtual Technician: Wiring & Safety ⚠️

• VCC: Connect to 5V.

• GND: Connect to Ground.

• Sensor Socket: Plug the HC-SR04 into the 4-pin female header on the front. Ensure the sensor faces OUTWARD.

• Serial Header (Optional): TX/RX pins are for sending data to a PC/Arduino. Not needed for standalone use.

• Note: The HC-SR04 Sensor is SOLD SEPARATELY. This product is the display board only.

Accessories

• Included in the Package:

  • 1 x Digital Display Control Board for HC-SR04 

• Required Accessories (Not Included):

  • Sensor: HC-SR04 Ultrasonic Module.

  • Power: 5V USB Source or Battery Pack.

Frequently Asked Questions (FAQ)

1. Does this include the HC-SR04 sensor? No. This is the control board only. You must buy the HC-SR04 sensor separately or use one you already own.

2. Do I need to program it? No! It comes pre-programmed. It is truly plug-and-play.

3. Can I change the unit to inches? No, the firmware is hard-coded to display Centimeters (cm).

4. What is the maximum distance it can measure? Ideally up to 400cm (4 meters), depending on the quality of your HC-SR04 sensor.

5. Can I use it with the HY-SRF05 sensor? Yes, as long as it has the standard 4-pin layout (VCC, Trig, Echo, GND). 5-pin sensors might not fit physically.

6. How do I power it? Apply 5V DC to the VCC and GND pins on the white connector or the side header.

7. Why does the display show "---" or "000"? This means the sensor is out of range or not connected properly. Check if the HC-SR04 is pushed in all the way.

8. Is the display visible in sunlight? It is a standard red LED display. It is visible indoors but might be washed out in direct measuring sunlight.

9. Can I read the data on my computer? Yes! Connect the TX pin to a USB-TTL converter (like CP2102) and open a Serial Monitor (9600 baud) to see the distance values on your PC.

10. Does it work with 3.3V? It might turn on, but the HC-SR04 sensor usually requires 5V to range accurately. 5V is recommended.

11. How accurate is it? It is as accurate as the sensor itself, typically ±1cm.

12. Can I mount it on a panel? Yes, it has standard mounting holes at the corners.

13. Does it have a buzzer? No, but you can hack it! You can solder a buzzer to the alarm pin (on some versions) or read the Serial data with an Arduino to trigger an alarm.

14. Why is the reading jumping around? Sound waves bounce off soft surfaces (like clothes). Aim it at a hard, flat surface (wall/box) for stable readings.

15. What is the refresh rate? It updates approximately every 100-200ms.

16. Can I use a 9V battery? Not directly! You must use a 5V regulator (like 7805) or the board will burn.

17. Is it waterproof? No.

18. Can I re-program the STM8 chip? Technically yes, if you have an ST-Link programmer and know how to code for STM8, the SWIM pins are broken out. But for most users, it's read-only.

19. Does it support the waterproof JSN-SR04T sensor? Usually, yes, as JSN-SR04T works on the same Trig/Echo logic, but you will need to wire it manually as the plug won't fit the waterproof probe's cable.

20. What happens if I plug the sensor in backward? It won't work, and you risk heating up the components. Follow the silk screen markings on the PCB!