HS-S31A Crash Sensor – Digital Collision Switch Module for Robot Bump and Limit Detection

The HS-S31A Crash Sensor is a digital collision switch module for robot bumpers, limit detection, object-contact events, and simple mechanical input experiments. It converts a physical press or impact into a clean digital state that a microcontroller can read.

It is a practical match for the ELAB Nano V3, robot prototypes using an UNO R3 Prototype Expansion Board, and visual status projects with the RGB Full Color LED Module. Use software debouncing for stable event handling.

This module is better for direct contact detection than long-range proximity sensing. Mount it where a bumper or moving part can press the switch without damaging the PCB.

Technical Specifications

Board Layout & Label Guide

• Switch Lever – Physical contact area that triggers the sensor.
• Signal Pin – Digital output to controller GPIO.
• VCC – Module power input if required by board circuit.
• GND – Common ground.
• Mounting Holes – Secure the board in a repeatable position.
• Contact Path – Align the bumper or moving part with the switch.
• Debounce Note – Mechanical contacts bounce.
• Protection Note – Avoid excessive impact force.

Application Scenarios

1. Arduino Digital Input

Read the crash sensor digital output.

const int sensorPin = 2;void setup() { Serial.begin(115200); pinMode(sensorPin, INPUT);}void loop() { Serial.println(digitalRead(sensorPin)); delay(100);}

2. LED Event Output

Turn on an LED when the module is pressed.

const int sensorPin = 2;const int ledPin = 13;void setup() { pinMode(sensorPin, INPUT); pinMode(ledPin, OUTPUT);}void loop() { digitalWrite(ledPin, digitalRead(sensorPin));}

3. MicroPython GPIO Monitor

Monitor the digital output from a Pico-style board.

from machine import Pinimport timesensor = Pin(15, Pin.IN)while True: print(sensor.value()) time.sleep(0.1)

Packing List

• 1 x HS-S31A Crash Sensor Module

FAQ

Q: What does it detect?
A: Physical collision or switch contact.

Q: Is it analog?
A: No, it is a digital switch-style sensor.

Q: Can it be used as a limit switch?
A: Yes, it is well suited for limit and bumper inputs.

Q: Does it need debounce?
A: Yes, use software debounce.

Q: Can it measure force?
A: No, it only detects switch state.

Q: Can I use it with Arduino?
A: Yes, connect the signal to a digital input.

Q: Why does it trigger multiple times?
A: Mechanical bounce or vibration can create repeated pulses.

Q: How should it be mounted?
A: Secure it so impact force presses the switch cleanly.