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Department of Microelectronic Systems, Faculty of Electronics,
Telecommunications and Informatics, Gdansk University of Technology
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Simple calculator with PS/2 keyboard
Task: Design and implement a simple integer
calculator with addition and subtraction operations. The designed
circuit should work as similarly as possible to the traditional calculator.
Arguments and operators should be entered using PS/2 keyboard, input data and
the result should be displayed on LED display of prototype board.
An example of operation 1234+96=1330:
| Key (PS2) | Display |
| | 0000 |
| 1 | 0001 |
| 2 | 0012 |
| 3 | 0123 |
| 4 | 1234 |
| + | 1234 |
| 9 | 0009 |
| 6 | 0096 |
| = | 1330 |
| ESC. | 0000 |
- Divide the project into several blocks.
- Provide asynchronous reset for all the flip-flops.
- There should be no latches in the design.
- Before implementing the design, a simulation must be run using the testbench.
UCF file, Digilent Spartan-3, Spartan-3 3S200 FT256-4:
#########################################################################################
# Clock:
NET "clk_i" LOC = "T9" ; # 50 MHz clock
#########################################################################################
#########################################################################################
# Seven-segment LED display:
NET "led7_an_o<3>" LOC = "E13" ; # leftmost digit, active low
NET "led7_an_o<2>" LOC = "F14" ; # active low
NET "led7_an_o<1>" LOC = "G14" ; # active low
NET "led7_an_o<0>" LOC = "d14" ; # rightmost digit, active low
#
NET "led7_seg_o<7>" LOC = "E14" ; # segment 'a', active low
NET "led7_seg_o<6>" LOC = "G13" ; # segment 'b', active low
NET "led7_seg_o<5>" LOC = "N15" ; # segment 'c', active low
NET "led7_seg_o<4>" LOC = "P15" ; # segment 'd', active low
NET "led7_seg_o<3>" LOC = "R16" ; # segment 'e', active low
NET "led7_seg_o<2>" LOC = "F13" ; # segment 'f', active low
NET "led7_seg_o<1>" LOC = "N16" ; # segment 'g', active low
NET "led7_seg_o<0>" LOC = "P16" ; # segment 'dp', active low
#########################################################################################
#########################################################################################
# Push-buttons:
NET "rst_i" LOC = "L14" ; # BTN3 active high
#########################################################################################
#########################################################################################
# PS2 port:
NET "ps2_clk_i" LOC = "M16" ; #clock from PS/2
NET "ps2_data_i" LOC = "M15" ; #PS/2 data
#########################################################################################
Fig.1 Description of LED display connectors.
Example of displaying digit '2'
Additional information on reading PS/2 keyboard
