/* * switch_statements.c
 *
 *  Modified: 2 July 2026
 *  Author:  Dr. Schwartz, Khaled Hassan and Josh Weaver
 *  Purpose: To provide an example using GPIO port and
 *           demonstrate "switch" statements (case structures).
 *           Read from switches connected to Port D. Light up
 *           LEDs on Port Q in a certain fashion based on Port D.
 *           Of course, switch statements can be used to run any
 *           code, not just simple GPIO actions.
 *
 *           NOTE: This code is meant to work with the uTinkerer, 
 *           **NOT** the uPAD. PortQ's LEDs are active low.
 */

// INCLUDES 
#include <avr/io.h>

// INITIALIZATIONS
#define F_CPU 2000000       // ATxmega runs at 2MHz

// PROTOTYPES

// MAIN FUNCTION
int main(void)
{
// Initialize GPIO PORTs
	// Set lowest four bits of Port D as input
    PORTD_DIRCLR = 0x0F;        

    //set up LEDs on Port Q as output
	PORTQ_DIR = 0x0F;
	
	// 8bit variable to hold input from Port D
    uint8_t input;
	
    while(1)
    {
		// read lowest 4 bits on Port D
        input = PORTD_IN & 0x0F;    

        switch(input){
        case 8:
            PORTQ_OUT = ~(0x0C);  // C = 1100
            break;
            // If we don't break out now, the case for 8 
            //   will "fall through" to the case for 4, and 
            //   we will see0011 on the LEDs, not 1100. Try it!
        case 4:
            PORTQ_OUT = ~(0x03);  // 3 = 0011
            break;
        case 2:
            PORTQ_OUT = ~(0x05);  // 5 = 0101
            break;
        case 1:
            PORTQ_OUT = ~(0x0A);  // A = 1010
            break;
        default:  // What happens if we have more than one
                  //   switch on? or none at all?
                  // Let's display an "error" code.
			PORTQ_OUT = ~(0x0F);  
        
        // Note: I invert each of these values since the 
		//   LEDs are active-low
		
    	}
    }
}

// FUNCTIONS