Week 5

Question 1

debugging

Answer 1

correcting the difference between what you want and what the programm actually does

Question 2

how to go about debugging

Answer 2

• First understand and have an expectation of what a program does
• then extract info: meassure output, look at led’s, check the order in which things are happening
• review code: what path was executed to produce the output and what went wrong

Question 3

serial debugging

Answer 3

serial communication is usefull, keep the following in mind:
- using serial changes the timing of the program
- serial and interrupts do not go hand in hand
- serial is slow

use a debug mode that you can switch on and off

Question 4

how to serial debug

Answer 4

debug the smallest portion of code possible
turn of irrelevant code
write debug lines wherever you have doubts and on conditionals and return values
measure what the arduino does

Question 5

What to do if there is no serial output

Answer 5

check serial port on pc and check baudrate
print a debug line early in the setup
use the built in led to confirm the program is running

Question 6

what to do/causes if the program keeps running setup()

Answer 6

an error(memory acces or division by 0) causes arduino to crassh
a crash causes a reboot
look at variable declaration and usage
look at the math
variables that are not initialised have random values

Question 7

memory basics

Answer 7

a computer (memory) stores bits (1 or 0), a group of 8 bits is a byte
a single byte can accomodate 256 states
communication speed is described in bits (lowercase b)
adressable memory is a magnitude of 2 kiB = 1024 bytes

Question 8

pointer

Answer 8

reserve a piece of memory, it is a stored memory adress and can be initialised using malloc, it needs to be freed manually using “free”, otherwise it will overwrite itself leading to bugs