Difference between revisions of "Arduino/C3/Digital-Logic-Design-with-Arduino/English"

Learning objectives

• Implement and verify the AND, OR and XOR operations in assembly.
• Implement and verify simple Combinational Logic.

Pre-requisites

• Electronics and
• Assembly language

System Requirement

• Arduino UNO Board
• Ubuntu Linux operating system version 14.04

External Devices

• Breadboard
• Arduino UNO Board
• Seven Segment Display
• 220-ohm Resistor
• Decoder (7447 IC) and
• Jumper Wires

.include "/home/spoken/Assembly/m328Pdef.inc"

ldi r16, 0b00111100

out DDRD, r16

You can download and use it.

The highlighted code configures pins 2, 3, 4 and 5 of the Arduino as output pins.

ldi r17, 0b00000001

and r16,r17

This line performs bitwise AND operation on the bits of r16 and r17. The result is stored in r16.

The LSB of r16 has our result. This has to be shifted by two positions to the left.

This loop takes care of shifting the LSB of r16 twice.

start:

rjmp start

This displays either 0 or 1 on the Seven segment display.

dec r20 brne loopw ret

Then the value of r20 is decremented by 1.

If the value of r20 is not equal to zero, the loop is repeated again.

> cd /home/spoken/Assembly

> avra boolean.asm

Type, avra boolean.asm and press Enter.

avrdude -p atmega328p -c arduino -b 115200 -P /dev/ttyACM0 -U flash:w: boolean.hex

avrdude space hyphen p space atmega328p space hyphen c space arduino space hyphen b space 115200 space hyphen capital P space forward slash dev forward slash ttyACM0 space hyphen capital U space flash colon wcolon boolean dot hex

and press Enter.

Assignment 1

Modify the values of r16 and r17 to verify the rest of the truth table of AND.

Replace the keyword and in the program with or to perform logical OR operation.

Replace the keyword and in the program with xor to perform logical XOR operation.

A = W′

B = WX′Z′ + W′X

C = WXY′ + X′Y + W′Y

D = WXY + W′Z

Here W, X, Y and Z are the inputs.

A, B, C and D are the outputs.

Let us consider the first row of the truth table. Thus, all the inputs will be zeros.

As per the truth table, we can expect the output as 1.

We will display the output on the seven segment display.

ldi r16, 0b00111100

out DDRD, r16

This line configures pins 2,3,4 and 5 of the Arduino as output pins.

ldi r30, 0b00000000

;W = r0

ldi r17, 0b00000000

mov r0, r17

;X = r1

ldi r18, 0b00000000

mov r1, r18

;Y = r2

ldi r19, 0b00000000

mov r2, r19

;Z = r3

ldi r20, 0b00000000

mov r3, r20

The values of input variables W, X, Y and Z are stored in registers r17, r18, r19 and r20 respectively.

The values of r17, r18, r19 and r20 are stored in the dummy variables r0, r1, r2 and r3.

These values are used to restore the original registers after performing operations.

rcall comp

mov r21, r16

mov r4, r21

;W'= r4

mov r16, r18

rcall comp

mov r22, r16

mov r5, r22

;X'= r5

mov r16, r19

rcall comp

mov r23, r16

mov r6, r23

;Y'= r6

mov r16, r20

rcall comp

mov r24, r16

mov r7, r24

;Z'= r7

The complement of W, X, Y and Z are calculated and stored in r21, r22, r23 and r24 respectively.

The values of r21, r22, r23 and r24 are stored in the dummy variables r4, r5, r6 and r7.

lsl r4

or r30, r4

Now, we have implemented the first equation.

Next, we perform two left shift operations and store the value in r30.

Thus, the third bit of the r30 has the value of A.

They might have changed during previous operations.

and r0, r5

and r0, r7

and r4, r1

or r0, r4

lsl r0

lsl r0

lsl r0

or r30, r0

The value in r0 is left shifted thrice and stored in r30.

Now, the fourth bit of r30 holds the result of B.

;Logic for C

and r0,r1

and r0,r6

and r5,r2

and r4,r2

or r0,r5

or r0,r4

lsl r0

lsl r0

lsl r0

lsl r0

or r30, r0

The value in r0 is left shifted four times and stored in r30.

Now, the fifth bit of r30 holds the result of C.

;Logic for D

and r0,r1

and r0,r2

;

and r4,r3

;

or r0,r4

lsl r0

lsl r0

lsl r0

lsl r0

lsl r0

or r30,r0

The value in r0 is left shifted five times and stored in r30.

Now, the sixth bit of r30 holds the result of D.

start:

rjmp start

comp:

mov r31, r16

ldi r16, 0b00000001

eor r16, r31

ret

reload:

mov r0,r17

mov r1,r18

mov r2, r19

mov r3,r20

mov r4, r21

mov r5, r22

mov r6, r23

mov r7, r24

ret

> cd /home/spoken/Assembly

> avra combination.asm

Let us clear the terminal

avrdude -p atmega328p -c arduino -b 115200 -P /dev/ttyACM0 -U flash:w: combination.hex

• To upload, press the up arrow to get the previous command.

• Now change the filename as shown and press Enter.

Change the values of W, X, Y and Z and verify different rows of the truth table.

Summary

• Implement and verify the AND, OR and XOR operations in assembly.
• Implement and verify simple Combinational Logic.

About Spoken Tutorial project

Please download and watch it.

Spoken Tutorial workshops

For more details, please write to us.

Forum for specific questions

Acknowledgement

More information on this mission is available at

this link.

This is Priya from IIT Bombay signing off.

Thanks for watching.