Microchip Technology Inc

Remote Keyless Entry

Remote Keyless Entry (RKE) System enables the locking and unlocking of the car doors without having to insert a key into the door lock. By depressing the button on the key fob, an encoded ultra-high frequency (UHF) signal is transmitted to the receiver module located in the car. The receiver module authenticates the signal. Upon positive recognition, it instructs the electronic control module (ECU) to toggle the lock.

Design Considerations
  • Robust, Keeloq® security IC-based microcontroller family with a small footprint
  • Low quiescent power
  • Secure authentication algorithm
  • Reliable wireless communication
  • PIC12 and PIC16 microcontrollers with the KeeLoq® security IC peripherals and low-power characteristics provide the system designer with flexible options in addressing the requirements for the transmitter. The PIC18 and PIC24 microcontrollers are suitable for the receiver module. The nanoWatt XLP, extreme low-power, microcontrollers provide industry-leading operating and standby currents that support long battery life. The battery life requirements for the key fob are significant and the requirements for the receiver module to function when the ignition is off make power conservation a priority.
  • KeeLoq security IC is an industry-wide recognized encryption algorithm with several hundred million units delivered to global car OEMs. KeeLoq security IC is a non-linear encryption algorithm that creates a unique transmission on every button depression. This capability makes code capture and resend schemes ineffective. For additional information on the KeeLoq secuirty ICs algorithm, please visit www.microchip.com/KeeLoq.
  • For ultra-high frequency communication between the key fob and the receiver module, the transmitter solutions allow the system designer to perform frequency shift keying (FSK) or amplitude shift keying (ASK) modulation to generate the transmissions. Corresponding receiver solutions are available to perform the filtering and decryption of the wireless data transmissions.
  • Utilizing the small footprints of the PIC® microcontrollers, the microcontroller may be integrated directly into the key fob packaging. While key fob is carried by the driver, the fob packaging is extremely important and the small footprints of the microcontroller provide flexibility for the designer of the fob packaging.
Development Tools