Interrupts lab

Question 1

What does SFR stand for in the 8051 datashhet?

Answer 1

Special function register

Question 2

What is the external interrupt in the lab and which pin/port is it connected to?

Answer 2

A button EX0
-connected to P3.2/ INT0 pin

Question 3

What is the name of the register that enables the interrupts in the lab?

Answer 3

IEN0
Interrupt enable control 0

Question 4

What is the purpose of the TMOD register?

Answer 4

When M00 (lsb) is set to 1, the timer is merged into a 16-bit timer

Question 5

Utilising the IEN0 register, how can all the interrupts be set in one instruction?

Answer 5

with EA being the msb and EX0 the lsb, it can be written as
MOV IE, #10000011B (or #083H)

Question 6

What is the purpose of the CJNE instruction?

Answer 6

Compares the button press operand with the interrupt. If the button has been pressed, when safe, the program will do the light sequence for pedestrian.

Question 7

What is the time of the interrupts?

Answer 7

50ms

Question 8

Why can’t the interrupt wait more than 1 second?

Answer 8

The timer is only 16-bits

Question 9

What is the purpose of the debugger?

Answer 9

Allows us to click through the program and see the program memory address of each instruction