LFRD001 Remote Keyless Entry
Created: Feb 27, 2017
No description available.
This reference design is a demonstration platform for the MAX1472 transmitter and the MAX1473 receiver for exercising both products as a remote keyless entry (RKE) demonstrator system. Both the transmitter and the receiver are incorporated with a MAXQ610 microcontroller that is preprogrammed to operate as an RKE system and can be programmed by the end user through a JTAG interface MAXQ® USB-to-JTAG board (MAXQJTAG-USB).
A simple interface is provided on the transmitter (Tx) board, including four independent momentary switches and a user feedback LED. The Tx board includes a built-in printed-circuit board (PCB) antenna and operates off of a single CR2032 coin cell battery. The receiver (Rx) board includes one momentary switch (for power) and five LED connections (for interface) to the microcontroller. In this reference design, the transmitter has been preprogrammed with a semi-unique ID (0x012345XX). This 4-byte value has been flashed into the MAXQ610 as part of the firmware-encoding process and can be easily changed by reprogramming the Tx microcontroller. To link the receiver system to the transmitter system, the user simply needs to set the "pair" flag on the receiver and send a valid signal with the transmitter to be paired.
This simple reference design has only four input switches on the transmitter, so 2 bytes of "function" is overkill. Again, this structure can be modified to suit the purposes of the user. In this application, when button A is pressed, the function value is 00 01. When button B is pressed, the function value is 00 02, and so forth. The function value is used to convey information (with individual buttons having their own bit), so it is possible to indicate multiple button presses simultaneously. In this instance, if buttons B and D were pressed together, the function value would be represented as 00 0A (this multi-button operation has not been implemented in the design). This is an arbitrary definition for the structure of the function value and it can always be modified by the user.