5.2 Remote Keyless Entry Operation

The RKE functionality is tested using the base station hardware (ATSAMC21-XPRO/ATA5831-XPRO) and the ATAB5702A fob board. The RKE functionality can be observed using the RKE Message Status window. On the fob, all three buttons provide RKE command messages. Each button also has two types of press actions – short press and long press, with each type handled differently. The following table shows how these are currently configured.

Table 5-1. Fob Push Buttons Functionality
Button ActionSW1SW2SW3
Short pressLockUnlock driver doorOpen trunk
Long pressRemote startUnlock all doorsClose trunk

Except for a long press of SW1, all of the other buttons transmit the RKE command messages using FSK modulation at 9.6 kbps. To carry out a long-range remote start function, a long press of SW1 changes to ASK modulation at 1 kbps. The remote start function command reduces the transmitted data rate. The decrease in data rate enhances the RF sensitivity of the RF transceiver board, which increases the range. The transmitting and receiving devices are seamlessly changed, demonstrating their power and flexibility.

For high-quality performance, even in the presence of noise, each button press sends three RKE messages sequentially on three different UHF channels, referred to as Time and Frequency Domain Redundancy. Thus, it increases the probability of successful reception of at least one of the messages.

Note: For more details on the RF protocol, refer to the AVR411: Secure Rolling Code Algorithm for Wireless Link Application Note. For more details on time and frequency domain redundancy, refer to the ATAN0014 RF System Architecture Considerations Application Note.