ūüĆü Writing in the air with LEDs

Everyone probably knows about the effect of the resulting inscription or pattern when the bar is quickly moved, sometimes a disc with a strip of LEDs that light up in a specially synchronized manner. The effect is called persistence. The effect itself is based on the inertia of the human eye. In order for such an effect to occur, the LEDs must light up at certain points in time so that they shine at fixed points in space when moving left-right.

In the design, which will be discussed, the author used an accelerometer on a circuit board with an LED strip and Arduino Diecimila for control. Power is supplied via USB, but you can connect and stand-alone.

Assembly

Installation was made on a breadboard. The LED strip, direct connectors for connection to the Arduino board and the edge connector for the accelerometer were mounted. The board connects to the Arduino as a standard expansion card.

The small green board is a three-axis accelerometer, from which the value is taken through the analog inputs of the Arduino. Depending on the acceleration, the accelerometer changes the voltage at its outputs.

Code:

// Display goes on PORTD
// GS1 on 10 Sensitivity Selection pins
// GS2 on 11 +- 4g selected here
// SLEEP on 12 and active LOW

int GS1 = 10;
int GS2 = 11;
int SLEEP = 12;

int Y=0; // Temp
int p=0; //Temp

// Tells the microcontroller how to write letters. Little Kid.
// Taken from Sparkfun Library
int text_array[475] = {
0x00,0x00,0x00,0x00,0x00,/*space*/ // is 32 in ASCII
0x00,0xF6,0xF6,0x00,0x00,/*!*/
0x00,0xE0,0x00,0xE0,0x00,/*"*/
0x28,0xFE,0x28,0xFE,0x28,/*#*/
0x00,0x64,0xD6,0x54,0x08,/*$*/
0xC2,0xCC,0x10,0x26,0xC6,/*%*/
0x4C,0xB2,0x92,0x6C,0x0A,/*&*/
0x00,0x00,0xE0,0x00,0x00,/*'*/
0x00,0x38,0x44,0x82,0x00,/*(*/
0x00,0x82,0x44,0x38,0x00,/*)*/
0x88,0x50,0xF8,0x50,0x88,/***/
0x08,0x08,0x3E,0x08,0x08,/*+*/
0x00,0x00,0x05,0x06,0x00,/*,*/
0x08,0x08,0x08,0x08,0x08,/*-*/
0x00,0x00,0x06,0x06,0x00,/*.*/
0x02,0x0C,0x10,0x60,0x80,/*/*/
0x7C,0x8A,0x92,0xA2,0x7C,/*0*/
0x00,0x42,0xFE,0x02,0x00,/*1*/
0x42,0x86,0x8A,0x92,0x62,/*2*/
0x44,0x82,0x92,0x92,0x6C,/*3*/
0x10,0x30,0x50,0xFE,0x10,/*4*/
0xE4,0xA2,0xA2,0xA2,0x9C,/*5*/
0x3C,0x52,0x92,0x92,0x0C,/*6*/
0x80,0x86,0x98,0xE0,0x80,/*7*/
0x6C,0x92,0x92,0x92,0x6C,/*8*/
0x60,0x92,0x92,0x94,0x78,/*9*/
0x00,0x00,0x36,0x36,0x00,/*:*/
0x00,0x00,0x35,0x36,0x00,/*;*/
0x10,0x28,0x44,0x82,0x00,/*<*/
0x28,0x28,0x28,0x28,0x28,/*=*/
0x00,0x82,0x44,0x28,0x10,/*>*/
0x40,0x80,0x8A,0x90,0x60,/*?*/
0x7C,0x82,0xBA,0xBA,0x62,/*@*/
0x3E,0x48,0x88,0x48,0x3E,/*A*/
0xFE,0x92,0x92,0x92,0x6C,/*B*/
0x7C,0x82,0x82,0x82,0x44,/*C*/
0xFE,0x82,0x82,0x82,0x7C,/*D*/
0xFE,0x92,0x92,0x92,0x82,/*E*/
0xFE,0x90,0x90,0x90,0x80,/*F*/
0x7C,0x82,0x82,0x8A,0x4E,/*G*/
0xFE,0x10,0x10,0x10,0xFE,/*H*/
0x82,0x82,0xFE,0x82,0x82,/*I*/
0x84,0x82,0xFC,0x80,0x80,/*J*/
0xFE,0x10,0x28,0x44,0x82,/*K*/
0xFE,0x02,0x02,0x02,0x02,/*L*/
0xFE,0x40,0x20,0x40,0xFE,/*M*/
0xFE,0x60,0x10,0x0C,0xFE,/*N*/
0x7C,0x82,0x82,0x82,0x7C,/*O*/
0xFE,0x90,0x90,0x90,0x60,/*P*/
0x7C,0x82,0x82,0x86,0x7E,/*Q*/
0xFE,0x90,0x98,0x94,0x62,/*R*/
0x64,0x92,0x92,0x92,0x4C,/*S*/
0x80,0x80,0xFE,0x80,0x80,/*T*/
0xFC,0x02,0x02,0x02,0xFC,/*U*/
0xF8,0x04,0x02,0x04,0xF8,/*V*/
0xFC,0x02,0x0C,0x02,0xFC,/*W*/
0xC6,0x28,0x10,0x28,0xC6,/*X*/
0xC0,0x20,0x1E,0x20,0xC0,/*Y*/
0x86,0x8A,0x92,0xA2,0xC2,/*Z*/
0x00,0x00,0xFE,0x82,0x00,/*[*/
0x00,0x00,0x00,0x00,0x00,/*this should be / */
0x80,0x60,0x10,0x0C,0x02,/*]*/
0x20,0x40,0x80,0x40,0x20,/*^*/
0x01,0x01,0x01,0x01,0x01,/*_*/
0x80,0x40,0x20,0x00,0x00,/*`*/
0x04,0x2A,0x2A,0x2A,0x1E,/*a*/
0xFE,0x12,0x22,0x22,0x1C,/*b*/
0x1C,0x22,0x22,0x22,0x14,/*c*/
0x1C,0x22,0x22,0x12,0xFE,/*d*/
0x1C,0x2A,0x2A,0x2A,0x18,/*e*/
0x10,0x7E,0x90,0x80,0x40,/*f*/
0x18,0x25,0x25,0x25,0x1E,/*g*/
0xFE,0x10,0x10,0x10,0x0E,/*h*/
0x00,0x12,0x5E,0x02,0x00,/*i*/
0x02,0x01,0x01,0x11,0x5E,/*j*/
0xFE,0x08,0x08,0x14,0x22,/*k*/
0x00,0x82,0xFE,0x02,0x00,/*l*/
0x3E,0x20,0x1C,0x20,0x1E,/*m*/
0x3E,0x20,0x20,0x20,0x1E,/*n*/
0x1C,0x22,0x22,0x22,0x1C,/*o*/
0x3F,0x24,0x24,0x24,0x18,/*p*/
0x18,0x24,0x24,0x3F,0x01,/*q*/
0x3E,0x10,0x20,0x20,0x10,/*r*/
0x12,0x2A,0x2A,0x2A,0x04,/*s*/
0x00,0x10,0x3C,0x12,0x04,/*t*/
0x3C,0x02,0x02,0x02,0x3E,/*u*/
0x30,0x0C,0x02,0x0C,0x30,/*v*/
0x38,0x06,0x18,0x06,0x38,/*w*/
0x22,0x14,0x08,0x14,0x22,/*x*/
0x38,0x05,0x05,0x05,0x3E,/*y*/
0x22,0x26,0x2A,0x32,0x22,/*z*/
0x00,0x10,0x6C,0x82,0x82,/*{*/
//0x00,0x00,0xFF,0x00,0x00,/*|*/
0x04,0x02,0xFF,0x02,0x04,/*|, arrow*/
0x82,0x82,0x6C,0x10,0x00,/*}*/
0x08,0x10,0x18,0x08,0x10/*~*/
};

// Displays the text
void display(char c)
{
int i = (c - 32)*5;
for ( int temp = i; temp < i + 5; temp++ ) {
PORTD = text_array[temp]; delayMicroseconds(500);
PORTD = 0x00; delay(3);
}
PORTD = 0x00; delay(3);
}

void setup()
{
pinMode(0,OUTPUT); // Set display as OUTPUT
pinMode(1,OUTPUT);
pinMode(2,OUTPUT);
pinMode(3,OUTPUT);
pinMode(4,OUTPUT);
pinMode(5,OUTPUT);
pinMode(6,OUTPUT);
pinMode(7,OUTPUT);
pinMode(8,OUTPUT);
pinMode(9,OUTPUT);
pinMode(10,OUTPUT);
pinMode(11,OUTPUT);
pinMode(12,OUTPUT);
pinMode(13,OUTPUT);

digitalWrite(GS1,HIGH); // Sensitivity Select
digitalWrite(GS2,LOW);
digitalWrite(SLEEP,HIGH); // Don't let the Accelerometer sleep !!!
}

void loop()
{
Y = analogRead(1); // Read the sensor...
if ( Y > 650)
{
p++;
if(p=2) // Take alternate acceleration...
{
p=0;
delay(60); // Wait a moment before starting

display('P'); // Paaaaraaammm...
display('a');
display('r');
display('a');
display('m');
display(':');
display('-');
display(')');
display(' ');
}
}
}

Now it remains to connect the assembly to the computer and swing it.

  • Jul 24, 2019
  • Category: Arduino
  • Comments: 0
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