C++

Forum

 
Need Help in circuit diagram of 8*8 reed switch matrix

miyayoung (1)
I am designing 8*8 reed switch matrix which will be connected to Arduino. I am using Arduino Duemilanove. I have completed the matrix portion but don't know how to connect and where to connect the other elements. My Matrix circuit

I decided to use the following items:

Arduino (Duemilanove)
64x Reed Switch
64x Diode (1N4148) Here is the datesheet:http://www.componentschip.com/pdf/62-1N4148-TP.pdf

20x Resistors (10K)
1x 74HC595 (here is the datesheet: http://www.componentschip.com/details/Texas-Instruments/74HC595.html

1x 74HC165

I dont know where to place the Resistors and shift Registers and connection from shift registers to arduino. I need help in the circuit diagram. Please help me out with the circuit diagram.
Jerrydgevdev (3)
You can use the internal pullups of the arduino if you're willing to accept that reading a "1" means that no piece is there and reading a "0" means a piece is there.

Connect each wire up to a pin on the arduino.

You need to configure the pins connected to the letter wires as inputs with their pullups enabled. Set the number pins to inputs as well, but without the pullup enabled so that they are floating. The number pins will be each set as an output in sequence with the value being low (non-active number pins are set back to inputs).

Example

Configure the outputs and inputs in setup:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
 
pinMode(2, INPUT_PULLUP);
pinMode(3, INPUT_PULLUP);
pinMode(4, INPUT_PULLUP);
pinMode(5, INPUT_PULLUP);
pinMode(6, INPUT_PULLUP);
pinMode(7, INPUT_PULLUP);
pinMode(8, INPUT_PULLUP);
pinMode(9, INPUT_PULLUP);
pinMode(10, INPUT);
pinMode(11, INPUT);
pinMode(12, INPUT);
pinMode(13, INPUT);
pinMode(14, INPUT); //A0
pinMode(15, INPUT); //A1
pinMode(16, INPUT); //A2
pinMode(17, INPUT); //A3
pinMode(18, INPUT); //A4


Make a function to scan the rows into an array of bytes:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
 
void scan_rows(uint8_t *rows)
{
    uint8_t i, j;

    for (i = 0; i < 8; i++)
    {
        if (i)
        {
            pinMode(i+9, INPUT);
        }
        pinMode(i+10, OUTPUT);
        digitalWrite(i+10, LOW);
        for (j = 2; j <= 9; j++)
        {
            rows[i] <<= 1;
            if (digitalRead(j))
                rows[i] |= 1;
        }
    }
    pinMode(18, INPUT);
}


Now, just call that function with a pointer to an array with 8 bytes in it whenever you need to scan the board. Each byte in the array represents one of the rows and each bit represents a column.
Topic archived. No new replies allowed.