Introduction to Embedded Systems

Question 1

What are the two options for binary?

Answer 1

0 or 1

Question 2

What are the options for Hexadecimal?

Answer 2

0-9, A, B, C, D, E, F

Question 3

How many bits does a binary digit take up?

Answer 3

1 bit

Question 4

How many bits are in a byte?

Answer 4

8

Question 5

What number does 1101 represent?

Answer 5

13
2^3 + 2^2 + 2^0 = 13

Question 6

Regarding voltage, what do 0 and 1 represent?

Answer 6

0 = Low Voltage
1 = High Voltage

Question 7

What are the prefix’s for writing binary numbers?

Answer 7

0b
0B
B

Question 8

What are the prefix’s for a hexidecimal number?

Answer 8

0x
0X

Question 9

What is 0b01101010 in Hexadecimal?

Answer 9

0x6A

Question 10

What is 0x2E in Binary?

Answer 10

0b00101110

Question 11

How do we notate Not in coding?

Answer 11

Y = ~A
Y is not A

Question 12

If x=0xE3 and y=~x, what is y?

Answer 12

0x1C

Question 13

How do we notate AND in coding?

Answer 13

Y=A&B

Question 14

If a = 0b01010110 and b = 0b10100101, and y=a&b, what is y?

Answer 14

y = 0b00000100

Question 15

How do we notate Or in coding?

Answer 15

Y=A|B

Question 16

If a = 0b00111011, b = 0b11100010, and y=a|b, what does y equal?

Answer 16

y = 0b11111011

Question 17

What does XOR represent?

Answer 17

An exclusive or, meaning that only one of the options can be positive to receive a positive output

Question 18

How do we represent XOR in code?

Answer 18

Y=A^B

Question 19

If a = 0b01100011, b = 0b11011010 and y = a^b, what does y equal?

Answer 19

y = 0b10111001

Question 20

unsigned char x;
unsigned char y;
if (x>=10){
y=2*x}
else{
y=x+2}

If x=5, what does y equal?
If x=12, what does y equal?

Answer 20

If x=5, then y = 5+2 = 7
If x=12, then y = 2 * 12 = 24

Question 21

Why do we use Setup Loops?

Answer 21

We can setup initial variables, and this section of code will only run once

Question 22

What is the numerical order of these pins?
xxxx xxxx

Answer 22

7654 3210

Question 23

Using the DDRx (Data Direction Register), how do we make all of the pins on port A input pins?

Answer 23

DDRA = 0b00000000;

Question 24

Using the DDRx (Data Direction Register), how do we make the lower 4 bits of port b as an output, and the higher 4 bits as an input?

Answer 24

DDRB = 0b00001111;

Question 25

What code do we use to output 0xFF on port B?

Answer 25

DDRB = 0b11111111; //Sets all pins of port B as outputs
PORTB = 0xFF; //Write's the data onto the ports

Question 26

Write a program to output a square wave to turn on the LED connected at pin PL2 (digital pin 47)

Answer 26

Step 1: Set PL2 as an output
Step 2: Create the main code

DDRL | = 0b00000100; //An alternative is DDRL | = 1<<2
PORTL | = 0b00000100; //This makes the high value
delay(1000);
PORTL & = 0b11111011; //This makes the low value
delay(1000);