Q$1($demo$)$: Design the following 'Keypad Number Display' which consists of the components:

A$)$ A keypad $(0-9,$ A$-$F$)$ represented by $16$ switches.

B$)16-$to$-4$ priority encoder $($behavioral$,$ refer to Lab$2,$ Part $2-1)$

C$)16x7$ BCH ROM $($it is a Hex$-$to$-7$Segment driver $($Lab$1$ demo Q$3)$ modeled as a ROM $($Lab$2$

Part $3))$

D$)7$ segment display

The design works as follows. The input $(16$ bit$)$ is given by the $16$ switches with each switch

representing a number in hexadecimal $($so the range will be $0$ to F$).$ Higher numbers have greater

priority. The input is then encoded into a $4$ bit number using the priority encoder $($active high$).$

The $4$ bit number is used as the input address to the ROM. The ROM should be initialized with $7$

segment output values. The output of the ROM is sent to the $7$ segment display. The display

should be off when no switch is activated. This will be controlled by an 'output enable' $($OE$)$

signal from the Encoder, inverted and connected to an$[0].$ That is$,$ when switches are off, $OE{?}^{\text{'}}0\text{'}$

and an All other times OE should be $\text{'}1\text{'}$ and so an$[0]$ should be $\text{'}0\text{'}($segments on$).$

Example: a $\text{'}9\text{'}$ on the keypad means $\text{'}0000001x\text{'}$ on the switches. This input will be

encoded to the corresponding $4-$digit binary, i$.$e$,"1001".$ This is given to the ROM as its input

address and the ROM should have the correct $7$ segment display code stored in address $"1001".$ The

ROM then outputs the $7$ segment binary code needed to display $\text{'}9\text{'}$ on the selected seven segment.

Hints:

Design the priority encoder first. You can simplify the design, with $16$ inputs, $4$ outputs

and an output enable $($OE$).$ Refer to Part $2-1$ where a $8-$to$-3$ encoder has been designed.

Design the ROM. To read out data from the ROM you need integers as indexes. But since the

input address is in binary, you need to convert the binary to unsigned integer. Refer to the

VHDL$\_1164$pkg$.$pdf section $2\mathrm{.}4$ on how to do that.

Use the encoder and ROM as components in a top level design. Appropriately connect the top level

input $($sw$[15$:$0])$ and output ports $($an$[7$:$0]$ and seg$[6$:$0])$ to switches, anodes and led segments in

the xdc file. Note in the toplevel architecture, an$[7$:$1]$ should be driven all $1s,$ while an$[0]$ should be

connected to the encoder $OE$ as shown in the figure.