Gauselink GL-A19 Ultrasonic Sensor Module

1. Introduction

The Gauselink GL-A19 Ultrasonic Sensor Module is a versatile and robust device designed for accurate distance, water level, and flow measurements. Featuring IP67 waterproofing and multiple output options (UART Automatic, UART Controlled, PWM Controlled, Switch), it is suitable for a wide range of industrial and DIY applications. This manual provides comprehensive information on the module's specifications, installation, operation, and troubleshooting to ensure optimal performance.

Image: The Gauselink GL-A19 Ultrasonic Sensor Module, highlighting its IP67 waterproof rating and wireless capabilities.

2. Specifications

Remarks: (a) & (b) Tested on 50*60cm flat carton box at internal lab. Temperature 25℃. The box was moving vertically in front of sensor. (c) Tested on 75mm(diameter)*100cm(length) PVC tube. The distance between sensor and tube is 100cm.

Image: Diagram illustrating the blind zone (0-28cm) and effective measurement range (28-450cm) of the sensor.

3. Product Features

• Strong Anti-interference: Designed to operate reliably in various environments.
• Fast Response: Quick detection and data output for dynamic applications.
• Stable Output Data: Provides consistent and reliable measurement readings.
• Precise Measurement: High accuracy for critical distance and level sensing.
• Low Power Consumption: Efficient design for extended operation.
• Wide Operating Temperature: Functional across a broad temperature range (-15℃ to 60℃).
• IP67 Protection: The main body is air-tightly sealed, protecting the circuit and extending sensor life.
• Compact Tiny Size: Probe diameter is only ø25mm, allowing installation in limited spaces. The sensor weighs approximately 19g.
• Quality Assurance: Manufactured in an ISO9001 certified factory, each product undergoes strict testing and carries a unique traceability code.

Image: The sensor demonstrating its IP67 waterproof capability.

Image: Comparison of the sensor probe diameter (ø25mm) with a 2-Euro coin.

Image: The sensor weighing 19g, lighter than a standard AA battery.

Image: Close-up of the sensor showing its traceability code and ISO 9001 certification.

4. Installation

4.1 Product Dimensions and Connector

The GL-A19 sensor module features a compact design. The connector type is HY2.0 with 4 pins. The cable length is approximately 325mm by default. Custom cable lengths may be available upon request.

Image: Detailed diagram showing the dimensions of the sensor module and the HY2.0-4P connector pinout.

Interface Definition:

• Pin #1 (Red): VCC - Power Input (3.3V-5V DC)
• Pin #2 (Black): GND - Ground
• Pin #3: RX - Receive (Trigger)
• Pin #4: TX - Transmit (Echo)

4.2 Mounting Recommendations

For optimal installation, the recommended diameter for the mounting hole in a panel is Φ23 ± 1mm. The maximum panel thickness should not exceed 6mm.

Image: Diagram illustrating the recommended installation hole diameter and maximum panel thickness.

5. Operation Modes

5.1 UART Automatic Output

In this mode, the module automatically outputs data. The behavior depends on the RX pin state:

• When the input RX is at a low level, the module outputs data based on the real-time value, with a response time of 100ms.
• When the trigger input pin "RX" is suspended or receives a high level, the module outputs data based on a processed value, which is more stable, with a response time of 500ms.

Note: These two modes can be switched by powering off and then re-powering on the module. The maximum voltage level for RX and TX pins is 5V DC.

Output Data Format:

• Data: 8 bits
• Stop: 1 bit
• Parity Check: No
• Baud Rate: 9600bps

Image: Table detailing the UART output format (Frame header, Data_H, Data_L, SUM).

Image: Example of UART output data and its conversion to decimal distance (1953mm).

Image: Screenshot of a serial assistant displaying received UART data and distance calculation.

5.2 UART Controlled Output

In this mode, the module is triggered by an external signal. When the trigger input pin "RX" receives a trigger pulse with a falling edge or any serial port data, the module performs a measurement. The output pin "TX" will then output one measurement data. The trigger cycle of the module must be greater than 70ms.

In standby, a watchdog is activated every 2 seconds. If the RX lead receives a falling edge pulse for less than 2 seconds, the watchdog will not be activated in the standby state.

Image: Timing diagram for UART Controlled Output, showing RX trigger and TX response (T1 > 70ms, T2 = 45-60ms).

5.3 PWM Controlled Output

When the trigger input “RX” receives a trigger pulse with a falling edge (0.1~6ms duration), the module performs a measurement. The output “TX” will then output a TTL level PWM high-level pulse width signal. The cycle period must be greater than 70ms.

If no object is detected, the output lead "TX" will output a fixed pulse width of about 35ms.

In PWM output mode, the watchdog is activated every 2 seconds in standby. If the RX pin receives a falling edge pulse for less than 2 seconds, the watchdog will not be activated.

Image: Timing diagram for PWM Output, showing RX trigger (T0) and TX echo (T1, T2).

PWM Output Calculation:

The distance (S) can be calculated using the formula: S = T₂ * V / 2, where T₂ is the PWM high-level pulse width time and V is the speed of sound in air (approx. 348m/s at normal temperature).

Simplified formula: S ≈ T₂ / 57.5 (S in cm, T₂ in microseconds μs).

Example: If T₂ = 10000μs, then S = 10000 / 57.5 ≈ 173.9 cm.

5.4 Switch Output

The module's default threshold value is 100cm (1 meter).

Functions of TX and RX Terminals:

• When a flat object is detected within the set threshold, the TX terminal outputs a high level (VOH). Note: This VOH is a signal and has no driving capability.
• When no object is detected or the object is beyond the threshold, the TX terminal outputs a low level (VOL).

The module checks the RX terminal every 1 second:

• If RX is suspended or has VOH input, the module outputs a processed (more stable) distance value with a 500ms response time.
• If RX has VOL input, the module outputs a real-time distance value with a 100ms response time.

Threshold Change:

The default threshold (100cm) can be changed to any value within the 28-450cm detection range. This requires a TTL to USB converter (available as a separate SKU) and a Serial Port Tester software.

• Connect the sensor's TX to the converter's RX, and the sensor's RX to the converter's TX.
• Use a Serial Port Tester to send hexadecimal commands in the specified format.

Image: Table showing the data format for host commands (TX) to change the threshold.

Image: Table showing the data format for client responses (RX) after a threshold change command.

Example: Sending FB 05 03 E8 EB (Host TX) and receiving FB 85 03 E8 00 6B (Client RX) indicates the threshold is set to 0x03E8 (1000mm).

Image: Screenshot of Serial Port Tester demonstrating a threshold change command and response.

Polarity Change of Output TX:

The default TX output polarity (VOH when object detected) can be changed to VOL using Serial Port Tester commands:

• To set TX to VOL: Host sends FB 06 00 00 01. Client responds FB 86 00 01 00 81.
• To revert to VOH (default): Host sends FB 06 00 01 02. Client responds FB 86 00 01 00 82.

5.5 RS485 Convertors for Extended Range

For UART Automatic or UART Controlled output sensors, if the distance between the sensor and the controller exceeds 3 meters, a pair of RS485 convertors can be used to extend the communication range up to 1km. Please select the SKU that includes these convertors if needed.

Image: An RS485 convertor board for extending UART communication range.

Image: Wiring diagram showing how to connect two RS485 convertors for extended UART communication.

6. Applicable Fields

The GL-A19 ultrasonic sensor module is suitable for a wide range of applications, including but not limited to:

• Automated Guided Vehicles (AGV)
• Parking Automation Systems
• AI Robots (for obstacle avoidance and navigation)
• Object Proximity and Presence Awareness
• Horizontal Level Measurement
• Liquid Level Measurement

The sensor supports development with micro-controller units (MCUs) such as Arduino and Raspberry Pi.

Image: Diagram illustrating various applications of ultrasonic sensors, including AGV, parking, and robotics.

Image: The sensor being used for liquid level measurement in a container.

7. Basic Principles of Ultrasonic Detection

An ultrasonic sensor determines the distance to an object by measuring the time difference between sending an ultrasonic wave and receiving its reflection. The sensor emits an ultrasonic wave (represented in red in the diagram) at time t0. This wave travels, reflects off an object, and returns to the sensor at time t1. The distance (S) is calculated using the formula:

S = V * (t1 - t0) / 2

Where 'V' is the speed of sound in air (approximately 348 m/s). In object detection applications, specific threshold values for 'S' can be set to trigger control actions when reached.

Image: Diagram illustrating the principle of ultrasonic distance measurement, showing the emitted (red) and reflected (green) waves.

8. Troubleshooting

8.1 UART Output Stuck at 280cm

A user reported the A19 UART output getting stuck at 280cm for extended periods. This behavior could be related to the sensor's blind zone and measurement range, or the specific UART output mode selected.

• Check Object Distance: Ensure the object being measured is outside the blind zone (0-28cm) and within the effective measurement range (28-450cm). If an object is consistently at the edge of the blind zone or range, it might lead to unstable readings or a 'stuck' value.
• Review UART Mode: If using UART Automatic output, consider the difference between 'real-time value' (100ms response) and 'processed value' (500ms response). The 'processed value' mode is designed for more stable data, which might appear less responsive but could prevent erratic readings. Ensure the RX pin is correctly configured (low for real-time, suspended/high for processed).
• Power Cycle: As noted in the UART Automatic Output section, power cycling the module can switch between real-time and processed value modes. Try a power cycle to reset the sensor's state.
• Environmental Factors: Ultrasonic sensors can be affected by environmental factors such as temperature fluctuations, air currents, and the material/angle of the target object. Ensure the environment is stable and the target object provides a clear reflection.
• Cable Integrity: Inspect the cable and connections for any damage or loose contacts that might interrupt data transmission.
• Controller/Software Issue: Verify that the receiving controller (e.g., ESP32) or serial monitoring software is correctly interpreting the UART data stream and not holding onto old values.

If the issue persists, consider contacting Gauselink technical support for further assistance.

9. User Tips

• ESP32 Compatibility: The UART model of the GL-A19 sensor can generally be used with an ESP32 chip, as both support UART communication. Ensure correct wiring of VCC, GND, RX, and TX pins, and configure the ESP32's UART peripheral to match the sensor's baud rate (9600bps) and data format (8N1).
• Testing Environment: When testing, especially for water level or flow, ensure the test setup mimics the actual application environment as closely as possible to get accurate and stable readings.
• Object Material: Be aware that different materials reflect ultrasonic waves differently. Smooth, dense surfaces provide better reflections than soft, porous ones.

10. Support

For technical assistance, customization requests, or any inquiries regarding the Gauselink GL-A19 Ultrasonic Sensor Module, please contact Gauselink technical support. Our R&D team is available to assist with specific project requirements and batch procurement.

Image: Illustration of 1-to-1 technical support available.

Image: Gauselink R&D team, indicating support for customization projects.

You can also refer to the product demonstration video for visual guidance:

Video: Demonstration of the GL-A19 ultrasonic sensor's distance and water level measurement capabilities.