For children and patients and old people and girls we often worry about their safety when they are at home in our absence or out to school and other work alone. Also girls’ safety is also the main concern for most of the parents and we often wish to have a device that helps them to send notification without getting the eyes of other people that they need assistance and help. So keeping this in mind we should not design a small device like a wrist watch or any small switch that helps us to send the SOS when they need any urgent assistance and help.Our device uses a  GSM module liek SIM800l or any other GSM module with a microcontroller that will send message for help to parents and guardian when they sak help just by pressing a simple button. So lets start designing our device with sopping of following components 
Bill Of Materials 

Prerequisite 

As we are using the Rp2040 based board, we need to prepare the ARDUINO IDE to program our RP2040 using the ARDUINO IDE . SO open the board manager and scratch the RP204p and install the MBED OS based bev board. 

We are also using GSM SIM800l Module so we need a library for using this module so open the library manager and search FONA and instal the FONA library 

Coding 

Now after installing the board and library we need to do coding . First we have to include the fona lu=iberary then we have set the hardware serial number for suing the SIM80l module here we are using the serial1 of RP2040 then  will create the setup function in where we inslize the serial1 communication with baudrate of 4800 ie the default baud rate of SIM 800l. Now we need the create the loop function and check if the emergency scth is pressed or not if switch is pressed then we will send the message to the set number asking the help. 

Connection
Now we need to connect  the modules asin connection diagram and then fix everything in case
 

Testing

Now insert the 2G network enable SIM in SIM800l Module wait a few seconds to get it connected to the network and power the device and now you can press the button on the device and it will send the SMS alert to the number set in the device regarding you needing urgent help.
Congrats you SOS device is ready to protect then alert your parents and loved one when you are in danger 
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