A quick course in Binary

The Sketch

Here’s the sketch for our animation demonstration:
// Project 24 - Animating an LED Matrix
#define DATA 6 // connect to pin 14 on the 74HC595
#define LATCH 8 // connect to pin 12 on the 74HC595
#define CLOCK 10 // connect to pin 11 on the 74HC595
byte smile[] = {B00000000, B00000110, B01000110, B00000000, B00011000,
B00000000, B11000011, B01111110}; int binary[] = {1, 2, 4, 8, 16, 32, 64, 128};
void setup()
{
pinMode(LATCH, OUTPUT); pinMode(CLOCK, OUTPUT); pinMode(DATA, OUTPUT); }
void loop()
{
int a, hold, shift;
 for ( shift = 0 ; shift < 9 ; shift++ )
{  for ( hold = 0 ; hold < 25 ; hold++ )
{
for ( a = 0 ; a < 8 ; a++ )
{
digitalWrite(LATCH, LOW);
 shiftOut(DATA, CLOCK, MSBFIRST, ~smile[a]>>shift); // columns shiftOut(DATA, CLOCK, LSBFIRST, binary[a]); // rows
digitalWrite(LATCH, HIGH);
delay(1);
}
}
}
}
The sketch holds the image on the matrix for 25 display cycles using a for loop at . The variable shift is the amount by which each byte will shift to the right. After each loop has completed, the variable shift is increased by 1 as shown at . Next, the display cycles repeat, and the image moves to the right by one LED column. By changing MSBFIRST to LSBFIRST in the third for loop at , we can change the direction that the face scrolls.

looking Ahead

In this chapter you have learned a lot of fundamental skills that will be used over and over in your own projects. LED displays are relatively hardy, so enjoy experimenting with them and making various display effects. However, there is a limit to what can be displayed, so in the next chapter we make use of much more detailed display methods for text and graphics.