A dot matrix test

matrix.ino

int column[8] = {A0,A1,A2,A3,A4,A5,A6,A7};
int row[8] = {A8,A9,A10,A11,A12,A13,A14,A15};

int pattern[8] = {0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01};
/*
void writeByte(int byte, int *port) {
    for(int i=0; i<8; i++){
        if(byte & (1<<i)) {
            digitalWrite(port[i], LOW);
        } else {
            digitalWrite(port[i], HIGH);
        }
    }
}
*/
void setup()
{
    for(int i=0; i<8; i++) {
        pinMode(column[i], OUTPUT);
        digitalWrite(column[i], HIGH);
        pinMode(row[i], OUTPUT);
        digitalWrite(row[i], LOW);
    }
}

void loop()
{

    // for every row of the matrix
    for(int r=0; r<8; r++) {
        // switch on the current row pin
        digitalWrite(row[r], LOW);
        // for every column of the matrix
        for(int c=0; c<8; c++) {
            // if the coresponding bit in the pattern for this row is a 1, 
            // set the column pin
            if(pattern[r] & (1 << c)) {
                digitalWrite(column[c], HIGH);
                delay(5);
                digitalWrite(column[c], LOW);
            // if not make sure the pin is off
            } else {
                delay(5);
                digitalWrite(column[c], LOW);
            }
        }
        // switch off the row when we finished it, procceed to the next one
        digitalWrite(row[r], HIGH);
    }
    
}