(Note - This is my first attempt at using Eagle to make a schematic, and I am not a fancy coder. I am sure there are more elegant ways to do this.. But would love to hear critiques, especially if something doesn't make sense.)

base idea from !(http://wardyprojects.blogspot.com/2011/05/74hc165-piso-shift-register-arduino.html)

PURPOSE Design a project to not use many pins on the MCU to read a DIPSWITCH and display the settings on the LCD. The 74HC165 IC is an 8-Bit Parallel-In/Serial-Out Shift Register which was used to limit the number of pins required

SCHEMATIC

CODE

    // Dipswitch and 74HC165 PISO test
    // NerdKit with ATmega328p
    // scottmc94

    #define F_CPU 14745600

    #include <avr/io.h>
    #include <inttypes.h>
    #include <avr/pgmspace.h>
    #include "../libnerdkits/lcd.h"
    #include "../libnerdkits/delay.h"
    #include "../libnerdkits/io_328p.h"

    // PIN DEFINITIONS:
    #define PIN_PL (1<<PC0) //pin 23 on atmega328p goes to pin 1 of 74HC165
    #define PIN_CP (1<<PC1) //pin 22 on atmega328p goes to pin 2 of 74HC165
    #define PIN_Q7 (1<<PC2) //pin 21 on atmega328p goes to pin 9 of 74HC165
    // GND to pin  8 of 74HC165
    // GND to pin 15 of 74HC165
    // +5v to pin 16 of 74HC165

    int CB(var,pos) {
        //Check bit to see if the dip switch is set
        int t;
        t = ((var) & (1<<(pos)));
        if (t > 0) {
            return 1;
        } else {
            return 0;
        }
    }

    int main() {

        //set as output
        DDRC |= PIN_PL;
        DDRC |= PIN_CP;

        //set as input
        DDRC &= ~PIN_Q7;

        //set OUTPUT HIGH
        PORTC |= PIN_PL;

        //set OUPUT LOW
        PORTC &= ~PIN_CP;

        int i;
        int j;
        int value;

        //  Check the dipswitch 10 times to make sure stable
        for(i = 0 ; i < 10 ; i++)
        {
            //load logic bits from the DIP switches
            PORTC &= ~PIN_PL; //LOAD BITS
            //reset "load" line, this freezes the internal buffer on both chips
            PORTC |= PIN_PL;
            value = 0;

            for(j=0; j<8; j++)
            {
                if(PINC & PIN_Q7) {
                    // pin high set bit
                    value |= (1<<j);
                } else {
                    // pin low - do nothing
                }

                //read next "switch"
                PORTC |= PIN_CP;
                delay_ms(5);
                PORTC &= ~PIN_CP;
            }
        }
        delay_ms(200);
        lcd_init();
        FILE lcd_stream = FDEV_SETUP_STREAM(lcd_putchar, 0, _FDEV_SETUP_WRITE);
        lcd_home();
        lcd_write_string(PSTR("DIPSWITCH: "));
    // the chip reads the bits from 7-0,
    //so I changed the display to match the dip switch.
    fprintf_P(&lcd_stream, PSTR("%d%d%d%d%d%d%d%d"),
    CB(value,7),CB(value,6),CB(value,5),
    CB(value,4),CB(value,3),CB(value,2),
    CB(value,1),CB(value,0));

    while(1) {

    }

    return 0;
}

Thanks for looking at this.

Scott

Nice, thank you.

Ralph

Hey Scott, you should contribute this to the Nerdkit Community Library.

Probable in the Library/How Do I section.

Ralph

I thought about that since it was a pretty controlled and limited test, but I wanted to see if I didn't have any major flaws that others saw first :)

Scott

Well I like your schematic, I looked at the code but I am not a programmer so I can not help with a critique or optimization.

If it works I'd definitely like to see it in the Library (that way I can find it when I need it, which I will :-).

Ralph

I will look at doing that, I have never done a library post before.