User manual

Basys MX3™ Board Reference Manual
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All the pins (AN0-3, CA-CG and DP) must be configured as digital output and Anode 0 and Anode 1 must have the
analog functionality disabled:
TRISBbits.TRISB12 = 0; //RB12 set as output
ANSELBbits.ANSB12 = 0; //RB12 analog functionality disabled
TRISBbits.TRISB13 = 0; //RB13 set as output
ANSELBbits.ANSB13 = 0; //RB13 analog functionality disabled
TRISAbits.TRISA9 = 0; //RA9 set as output
TRISAbits.TRISA10 = 0; //RA10 set as output
TRISGbits.TRISG12 = 0; //RG12 set as output
TRISAbits.TRISA14 = 0; //RA14 set as output
TRISDbits.TRISD6 = 0; //RD6 set as output
TRISGbits.TRISG13 = 0; //RG13 set as output
TRISGbits.TRISG15 = 0; //RG15 set as output
TRISDbits.TRISD7 = 0; //RD7 set as output
TRISDbits.TRISD13 = 0; //RD13 set as output
TRISGbits.TRISG14 = 0; //RG14 set as output
7.2 Functionality
A seven-segment display controller is implemented in the SSD library of the Basys MX3 library pack. Here are some
details on the implementation of the library:
 One array contains constant values for the segment’s configurations (one bit for each segment)
corresponding to various digits (0-9, A-F).
 When the user selects the values to be displayed, they are used as index into this segment’s configuration
table and the resulting configuration bytes are stored in global variables.
 Timer1 is used to generate interrupts every 3ms (corresponding to the period register PR1 = 3750).
 Every time the interrupt handler routine is called, the following operations are performed:
o The next digit becomes the current digit, in a circular approach (thus each digit will be addressed
once after 4 calls of the interrupt handler routine).
o All digits are deactivated by outputting 1 to their corresponding anodes.
o The cathodes are outputted according to the segment’s information corresponding to the
current digit.
o The current digit is activated (0 is outputted to its corresponding anode).