Arduino/C3/Digital-Logic-Design-with-Arduino/English

Visual Cue	Narration
Slide 1:	Welcome to the Spoken Tutorial on Digital Logic Design with Arduino.
Slide 2: Learning objectives	In this tutorial, we will learn to: Implement and verify the AND, OR and XOR operations in assembly. Implement and verify simple Combinational Logic.
Slide 3: Pre-requisites	To follow this tutorial, you should have basic knowledge of: Electronics and Assembly language
Slide 4: System Requirement	To record this tutorial, I am using: Arduino UNO Board Ubuntu Linux operating system version 14.04
Slide 5: External Devices	We also require some external devices such as: Breadboard Arduino UNO Board Seven Segment Display 220-ohm Resistor Decoder (7447 IC) and Jumper Wires
Show the image:	We will use the same circuit setup as we did for the decoder in the earlier tutorial.
show the live connection	Let us see the live connection setup.
	Now we will write an assembly program to verify the logical AND operations.
Open text editor	Open any text editor and type the following program.
Highlight according to narration: .include "/home/spoken/Assembly/m328Pdef.inc" ldi r16, 0b00111100 out DDRD, r16	m328Pdef.inc file and the source code are available in the code files link of this tutorial. You can download and use it. The highlighted code configures pins 2, 3, 4 and 5 of the Arduino as output pins.
ldi r16, 0b00000001 ldi r17, 0b00000001 and r16,r17	We are considering only the first bit of r16 and r17 for our boolean operations. Here, both are 1. This line performs bitwise AND operation on the bits of r16 and r17. The result is stored in r16.
ldi r20, 0b00000010	The rest of the program takes care of displaying this output. The LSB of r16 has our result. This has to be shifted by two positions to the left.
rcall loopw	This line of code calls the loop named loopw. This loop takes care of shifting the LSB of r16 twice.
out PORTD, r16 start: rjmp start	The value in r16 is sent to PORTD. This displays either 0 or 1 on the Seven segment display.
loopw: lsl r16 dec r20 brne loopw ret	Here, contents of r16 are left shifted once. Then the value of r20 is decremented by 1. If the value of r20 is not equal to zero, the loop is repeated again.
Save the code	I’ll save the code as boolean.asm in the home slash spoken slash Assembly folder.
Switch to the terminal.	Switch to the terminal.
Type, > cd /home/spoken/Assembly > avra boolean.asm	Go to the folder where boolean.asm file is saved. Type, avra boolean.asm and press Enter.
Point to the /home/spoken/Assembly folder	This will assemble the code and create a file boolean.hex.
Clear the terminal.	Let us clear the screen.
	Next we need to upload the code to the Arduino.
Type, avrdude -p atmega328p -c arduino -b 115200 -P /dev/ttyACM0 -U flash:w: boolean.hex	For this, type 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.
Point to the output	Now you can see that the digit one on the seven segment display is glowing.
Slide 7: Assignment 1	Pause the tutorial and do the below assignment. 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.
	Next, we will implement and verify few simple combinational logics.
Show the setup	Let us see the live connection setup. It will be the same as the previous setup.
Slide: A = W′ B = WX′Z′ + W′X C = WXY′ + X′Y + W′Y D = WXY + W′Z	We are going to implement these equations in our program and verify their truth table.
Truth Table:	This is the truth table for the equations shown above. 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.
	Let us write an assembly program to implement and verify these equations.
Open text editor	Open any text editor and type the following program.
.include "/home/spoken/Assembly/m328Pdef.inc" ldi r16, 0b00111100 out DDRD, r16	Let me explain the program. This line configures pins 2,3,4 and 5 of the Arduino as output pins.
;dummy for output 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	r30 is a dummy variable for storing the output. 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.
mov r16, r17 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 comp subroutine is used to find the complement of a variable. 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 lsl r4 or r30, r4	Note that A is nothing but the complement of W. 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.
rcall reload	The reload subroutine reloads the values r0, r1, r2, r3, r4, r5, r6 and r7 from its copies. They might have changed during previous operations.
;Logic for B and r0, r5 and r0, r7 and r4, r1 or r0, r4 lsl r0 lsl r0 lsl r0 or r30, r0	The logic for B is implemented and the result is stored in r0. The value in r0 is left shifted thrice and stored in r30. Now, the fourth bit of r30 holds the result of B.
rcall reload ;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 logic for C is implemented and the result is stored in 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.
rcall reload ;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 logic for D is implemented and the result is stored in 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.
out PORTD, r30 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	Finally, the value stored in r30 is sent to PORTD to be displayed.
	Save the code as combination.asm in the home slash spoken slash Assembly folder.
	Switch to the terminal.
Type, > cd /home/spoken/Assembly > avra combination.asm	Type, avra combination.asm and press Enter.
Point to the /home/spoken/Assembly folder	This will assemble the code and create a file combination.hex. Let us clear the terminal
Type, 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.
Point to the output	Now you can verify the truth table with the output shown on the seven-segment display.
Assignment:	Pause the tutorial and do the below assignment. Change the values of W, X, Y and Z and verify different rows of the truth table.
	This brings us to the end of this tutorial. Let us summarize.
Slide 11: Summary	In this tutorial, we learnt to: Implement and verify the AND, OR and XOR operations in assembly. Implement and verify simple Combinational Logic.
Slide 12: About Spoken Tutorial project	The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
Slide 13: Spoken Tutorial workshops	The Spoken Tutorial Project Team conducts workshops and gives certificates. For more details, please write to us.
Slide 14: Forum for specific questions	Please post your timed queries in this forum.
Slide 15: Acknowledgement	Spoken Tutorial project is funded by NMEICT, MHRD, Government of India. More information on this mission is available at this link.
	This tutorial has been contributed by FOSSEE and Spoken Tutorial Project, IIT Bombay.   This is Priya from IIT Bombay signing off. Thanks for watching.

Contributors and Content Editors

Nancyvarkey, Nirmala Venkat