Using Bolt 18F2550 system for RFID applications
FORMAT OF STRING: A TOTAL OF 16 BYTES
HARDWARE DETAILS OF RFID MODULE FOR BOLT 18F2550 SYSTEM:
Electronic diagram: DIAGRAM RFID.pdf
C18 APPLICATION PROGRAM HANDLING BIDIMENSIONAL ARRAYS
The application program contains the basic functions of the access control: identification of tag, comparison with a bidimensional array data and then display the name of the person on the LCD display 16 x 1. As an extension of the project, it is possible to add communication between the Bolt 18F2550 system and a PC to handle large data bases.
The program was developed using the C18 compiler v.3.40 and MPLAB IDE v.8.63. Using the capabilities of the C18 compiler, we used a two-dimensional array to store the list of names and ID codes.
A basic test program was done first: C18-BOLT-RFID.c
The complete application program is: C18-BOLT-RFID-3.c
In the application program, only 8 records were stored (one record per person), but could be up to 100 without any problems in the use of memory, which would consume only 2K of the 32K available. Note how the last 4 digits of the tag and the name of the person are stored in the same array, so as to facilitate identification.
Also, using the facilities for handling pointers, an array of arrays called "masterarray [ ]", based on pointers, is defined. This makes it possible to access any array element. The definition of the arrays used in the program is the following:
const char TAG[ ]=">>TAG<<";
A single standard function of C18 is used to read the string of 12 characters sent by the RFID module to Bolt system: