An interview question

Spudboy488 said:

Since you said that if the interviewer asked you the same question, you could mange. Now you're trying to know. You also claim that I also don't know.

Here's how I would do it.

Most micros have a port that can be written to all at once. For this example, we'll call it PORTA and we'll assume it's at least 4-bits wide.

The program in a simple form.

Code:

for x=0 to 15
   PORTA = x
next x

The output of PORTA will be:

Code:

0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

Output 0 changes every clock cycle
Output 1 changes every 2 clock cycles
Output 2 changes every 4 clock cycles
Output 3 changes every 8 clock cycles

4 pins. 4 different frequencies

.View attachment 115087

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