The SIM800L module needs special attention because it operates at 3.3V logic levels while Arduino uses 5V. We need a voltage divider circuit to protect the SIM800L from damage. If you are new to the ...

This project monitors voltage using a potentiometer connected to an Arduino. When the voltage reaches 4.8V or higher, the system automatically sends an SMS and makes a phone call using the SIM800L GSM ...

An emergency-response system built into a smart helmet. It uses GPS and GSM modules to send real-time location via SMS and initiate a call when an SOS button is pressed. SOS Emergency Alert ...