Question

In MPLAB write and compile (using the simulator) an assembly language program with the following functionality:

Configures pin RA2 of the PIC24to be an output to control an attached LED.

Configures pin RB13 of the PIC24 to be an input to read the value on an attached switch (this switch will connect to ground when pressed).

Configures pin RB13 to use the internal pull-up resistor.

After configuration, the LED will be "off" when the push-button is pressed, and "on" when it is released.

Remember, since this is an assembly language program you cannot use the C-language macros. Also, that in an assembly language program the name of a register is a reference to its memory location.

Answer 1

Start
        bank1                      ;Go to bank 1
        movlw b'1111111111111011'  ;Set the port pin types of RA
        movwf TRISA                ;RA2 port is set as output

        movlw b'0010000000000000'  ;Set the port pin types of RB
        movwf TRISB                ;RB13 is the input
        bank0                      ;Go to bank 0
MainLoop
        btfss PORTB,13             ;Read RB13 pin
        goto Button_Is_Off         ;If RB13 is '0', then goto Button_Is_Off
Button_Is_On
        bsf PORTA,2                ;Set RA2 output
        goto MainLoop              ;And go back to the Main Loop
Button_Is_Off
        bcf PORTB,13               ;Clear RB13 input
        goto MainLoop              ;And go back to the Main Loop