I'm looking for some help:
I put together a 3x3x3 led cube, which I hooked up to the arduino. It seems to work fine, except for showing one quirk: after 33 seconds (give or take 1s), it kind of hangs. It doesn't really hang, but I'll have to tell a bit more before I can explain that.
I use two shift registers, to shift out 12 bits (9 for the anodes of each led in a plane, and 3 for pulling each plane to ground via a transistor). The 12 bits are stored in 2 separate bytes in an array, and I use multiplexing by pulling the planes to ground one after another, so I have 6 bytes in the array for one configuration (describing status of all leds in the cube). For an 'animation', I have a multiple of six bytes in the array that I loop through. The code I use is based on the shift out tutorial:
//**************************************************************//
// Name : shiftOutCode, Predefined Array Style //
// Author : Carlyn Maw, Tom Igoe //
/Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
////Pin connected to DS of 74HC595
int dataPin = 11;
//holders for infromation you're going to pass to shifting function
byte data, data1;
byte dataArray[167];
int number = 28;
void setup() {
//set pins to output because they are addressed in the main loop
pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
Serial.begin(9600);
//Arduino doesn't seem to have a way to write binary straight into the code
//so these values are in HEX. Decimal would have been fine, too.
dataArray[0] = 0x2a; //00101010
dataArray[1] = 0x40; //01000000
dataArray[2] = 0x2a; //00101010
dataArray[3] = 0x20; //00100000
dataArray[4] = 0x2a; //00101010
dataArray[5] = 0x12; //00010000
...
dataArray[165] = 0x20; //00100000
dataArray[166] = 0x1c; //00011100
dataArray[167] = 0x12; //00010000
}
void loop() {
for (int j = 0; j < (number+1); j++) {
int time = millis();
while(millis() < (time + 250)){
for (int k = 0; k<3; k++) {
//load the light sequence you want from array
data = dataArray[j*6+2*k];
data1 = dataArray[j*6+2*k+1];
//ground latchPin and hold low for as long as you are transmitting
digitalWrite(latchPin, 0);
//move 'em out
shiftOut(dataPin, clockPin, data1);
shiftOut(dataPin, clockPin, data);
//return the latch pin high to signal chip that it
//no longer needs to listen for information
digitalWrite(latchPin, 1);
delay(5);
}
}
}
}
// the heart of the program
void shiftOut(int myDataPin, int myClockPin, byte myDataOut) {
// This shifts 8 bits out MSB first,
//on the rising edge of the clock,
//clock idles low
//internal function setup
int i=0;
int pinState;
//clear everything out just in case to
//prepare shift register for bit shifting
//digitalWrite(myDataPin, 0);
//digitalWrite(myClockPin, 0);
for (i=0; i<=7; i++) {
digitalWrite(myClockPin, 0);
if ( myDataOut & (1<<i) ) {
pinState= 1;
}
else {
pinState= 0;
}
//Sets the pin to HIGH or LOW depending on pinState
digitalWrite(myDataPin, pinState);
//register shifts bits on upstroke of clock pin
digitalWrite(myClockPin, 1);
//zero the data pin after shift to prevent bleed through
digitalWrite(myDataPin, 0);
}
digitalWrite(myClockPin, 0);
}
(note that I cut out part of the array)
Now the reason I say that it's not really 'hanging' is that the led cube displays a full configuration, not just one plane. This means that the arduino keeps on looping through k-values for a fixed j-value in the main loop(). The funny thing is that it is really time related: if I change the speed at which the animation runs (changing the 250 in "(time + 250)"), it still 'hangs' around 33 secs, and in a different configuration. But I really cannot find anything in the code that can explain this. Anybody else can? Or can it be a hardware related thing? Any other reason?
Thanks!
