Question

1- Explain the function of the ‘trisb’ Special Function Register(SFR). Where is it located in the PIC. Say what effect the following statement has:-
trisb = 0x03;

2- In a C program for a microcontroller, portb has been setup as all outputs and is assigned the hexadecimal value 0xD3. Determine the voltage levels on the pins of portb.


3- In the context of explaining the difference between the logical NOT operator(!) and the bitwise NOT operator(~) say what value portb will end up with in each of the following cases:-
a) portb = ~ (0x55);
b) portb = !(0x55);
 
4- Determine the value on the portb pins after the following C code statement is executed, if portb had an initial value of 0x40:-
portb = portb >> 2;

Answer 1