This project is based on the safety of a car by means of serial communication in radio frequency to start the car, the idea is for the user to enter the correct password by means of a matrix keyboard, this keyboard by means of a tone identifier , Passing through a PISO (Parallel Input Serial Output) because it is a 4-bit password in parallel and must be transmitted serially, then it reaches a receiver that passes through the SIPO (Serial Input Parallel Output) decoding process and this parallel data Enters the microcontroller PIC16F877A which is in charge of verifying that the password of 4 bits is correct, if the password is correct the microcontroller activates the ignition of the car passing through a power stage, if the password is correct, the microcontroller blocks the car.