Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	AJ-SR04M / RCWL-1670
Operating Voltage	3.3V - 5V DC
Detection Range	2cm to 400cm
Interface Type	UART Serial Output
Beam Angle	Approx. 15 degrees
Frequency	40kHz Ultrasonic
Waterproof Rating	IP67 Sealed Design
Operating Temperature	-20°C to +70°C
Dimensions	45mm x 20mm x 15mm
Application	Reverse Parking, Obstacle Avoidance

6 reviews

Anonymous

Mar 31, 2026

Rating: 4/5

Good value for money

Works exactly as described in the datasheet. Setup was straightforward using the provided documentation. It reacts quickly to obstacles, which is crucial for my autonomous vehicle prototype.

Anonymous

Mar 29, 2026

Rating: 5/5

Solid build quality

The casing feels very durable and the sealing looks professional. I am using this for an outdoor security alert system and it hasn't given me a single false alarm due to weather conditions.

Anonymous

Mar 18, 2026

Rating: 4/5

Great waterproofing, easy install

Installed this on the rear bumper of my golf cart. It has survived several rainstorms without any issues. The only reason for 4 stars is that the cable could be a bit longer, but otherwise excellent quality.

Anonymous

Mar 16, 2026

Rating: 5/5

Best ultrasonic sensor we've used

We bought a batch of these for our workshop classes. Students find the UART interface much less confusing to program. All units arrived working perfectly and have held up well to heavy handling.

Anonymous

Mar 11, 2026

Rating: 5/5

Perfect for my Arduino parking project

This sensor works flawlessly with my microcontroller setup. The serial output makes it much easier to integrate than the standard trigger/echo pins on older models. Distance readings are consistent and stable.

Anonymous

Mar 09, 2026

Rating: 5/5

Reliable ranging module

I've tested this against a laser measure and the accuracy is impressive for the price point. The integrated transceiver design saves a lot of space on my robot chassis. Highly recommended for DIY enthusiasts.

5 FAQ

Q: What is the maximum detection distance in bright sunlight?

A: Ultrasonic sensors are generally not affected by visible light. The maximum range remains approximately 400cm regardless of lighting conditions, though extreme wind or soft surfaces may affect accuracy.

Q: Does this sensor work directly with Raspberry Pi GPIO?

A: Yes, it works with Raspberry Pi. Since it uses UART serial communication, you will need to connect the TX pin of the sensor to the RX pin of the Pi and ensure voltage levels are compatible (3.3V logic).

Q: Can I submerge this unit completely underwater?

A: While it has an IP67 rating meaning it can withstand temporary immersion up to 1 meter for 30 minutes, it is designed primarily for splash resistance and rain protection, not continuous underwater operation.

Q: How do I calibrate the sensor if readings seem off?

A: The sensor comes pre-calibrated. If readings are inconsistent, check for obstructions near the transducer face or ensure the mounting surface is not vibrating. Software averaging filters can also smooth out minor fluctuations.

Q: Is there a library available for ESP32?

A: Yes, there are several open-source libraries available on GitHub specifically for the AJ-SR04M that support ESP32. You can search for 'AJ-SR04M ESP32 library' to find compatible code examples.

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