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Pzsmocn: Collision Sensor/Micro Snap Switch/Micro Limit Switch Module Compatible with Raspberry Pi and Arduino Board. for Smart Homes, Offices, 3D Printer and Teaching Interact with Robots. : Amazon.co.uk: Business, Industry & Science
python - Micro Switch implementation in Raspberry pi - Raspberry Pi Stack Exchange
Estop and Limit Switch using Interrupts - YouTube
How to Set Up Buttons and Switches on the Raspberry Pi - Circuit Basics