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Topic: Shiftbrite Help (Read 1 time) previous topic - next topic


Hi Guys,

I'm having some problems with a last minute project (it goes live this weekend!) and I was hoping someone could help me out. I'm trying to control a string of 12 shiftbrites from an arduino and some input from a photocell. I got my code working perfectly with two shiftbrites. The problem is when I add any amount of additional shiftbrites to the chain, the additional ones aren't working. The arduino is powered by usb and the chain is powered by a 6v 1.5A wall adapter that also grounded to the arduino. The shiftbrites are connected to each other with 24" 6pin jumper harness from pololu (http://www.pololu.com/catalog/product/1237). I also tried a 9v 650mA and a 5v 1A wall adapters with the same results. I also tried smaller chains of 3 and 4. Is there something I'm missing to get the additional ones working?

For reference, here's my code:

Code: [Select]

#define clockpin 13 // DI
#define enablepin 10 // LI
#define latchpin 9 // EI
#define datapin 11 // CI

#define NumLEDs 12

int LEDChannels[NumLEDs][3] = {0};
int SB_CommandMode;
int SB_RedCommand;
int SB_GreenCommand;
int SB_BlueCommand;
int count = 0;
int sensorPin = 0;
int sensorValue = 0;
int curR = random(1023);
int curG = random(1023);
int curB = random(1023);

// threshold values for interaction
int user1sensorVal = 700;
int user2sensorVal = 300;

void setup() {

   pinMode(datapin, OUTPUT);
   pinMode(latchpin, OUTPUT);
   pinMode(enablepin, OUTPUT);
   pinMode(clockpin, OUTPUT);
   SPCR = (1<<SPE)|(1<<MSTR)|(0<<SPR1)|(0<<SPR0);
   digitalWrite(latchpin, LOW);
   digitalWrite(enablepin, LOW);

   //Serial.println("Module ready");

void SB_SendPacket() {

    if (SB_CommandMode == B01) {
     SB_RedCommand = 120;
     SB_GreenCommand = 100;
     SB_BlueCommand = 100;

    SPDR = SB_CommandMode << 6 | SB_BlueCommand>>4;
    while(!(SPSR & (1<<SPIF)));
    SPDR = SB_BlueCommand<<4 | SB_RedCommand>>6;
    while(!(SPSR & (1<<SPIF)));
    SPDR = SB_RedCommand << 2 | SB_GreenCommand>>8;
    while(!(SPSR & (1<<SPIF)));
    SPDR = SB_GreenCommand;
    while(!(SPSR & (1<<SPIF)));


void WriteLEDArray() {

    SB_CommandMode = B00; // Write to PWM control registers
    for (int h = 0;h<NumLEDs;h++) {
  SB_RedCommand = LEDChannels[h][0];
  SB_GreenCommand = LEDChannels[h][1];
  SB_BlueCommand = LEDChannels[h][2];

    digitalWrite(latchpin,HIGH); // latch data into registers

    SB_CommandMode = B01; // Write to current control registers
    for (int z = 0; z < NumLEDs; z++) SB_SendPacket();
    digitalWrite(latchpin,HIGH); // latch data into registers


void fadeall(int rate, int fromred, int fromgreen, int fromblue, int tored, int togreen, int toblue) {
for (int i = 0; i < 33; i++) {
for (int j1 = 0; j1 < NumLEDs; j1++) {
LEDChannels[j1][0] = (fromred * (32 - i) + tored * i)/32;
LEDChannels[j1][1] = (fromgreen * (32 - i) + togreen * i)/32;
LEDChannels[j1][2] = (fromblue * (32 - i) + toblue * i)/32;

void loop() {
  // read photocell value
  sensorValue = analogRead(sensorPin);

  if (sensorValue<user2sensorVal) {
      // pulse red when user blocks all light
      fadeall(50, 1023, 0, 0, 0, 0, 0);
      fadeall(50, 0, 0, 0, 1023, 0, 0);
  } else if(sensorValue<user1sensorVal){
    // set chain to blue when shadow is detected
    for (int i = 0; i < NumLEDs; i++) {
      LEDChannels[i][0] = 0;
      LEDChannels[i][1] = 0;
      LEDChannels[i][2] = 1023;
  } else {
// randomly fade colors on default
    int tempR = random(1023);
    int tempG = random(1023);
    int tempB = random(1023);
    fadeall(50, curR, curG, curB, tempR, tempG, tempB);
    curR = tempR;
    curG = tempG;
    curB = tempB;

Thanks in advance!


Did you try connecting some other ShiftBrites as the first two in your chain? If at any point you shorted out or incorrectly connected the last ShiftBrite...it might work OK but not pass data down the chain.

Another thing to check is the cable wiring. Sometimes whoever assembles a cable swaps one of the wires accidentally.

Basically, start swapping out ShiftBrites and cables until you locate a part that has failed.

I assume by "not working" you mean they just don't light up at all.
Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store


I assume by "not working" you mean they just don't light up at all.

Hi macegr,

Thanks so much for writing back so fast. Correct, I'm not seeing any light at all. Although at the beginning I did see the whole chain flicker, but that was before I realized it wasn't grounded to the arduino for the clock. At another point, I did see a faint green light come from shiftbrite 3 and 4. I have tried randomly swapping shiftbrites into the first two, but I will take closer look tonight at the cables as well.



Turned out to be a bad cable as you described. Thanks so much for your help! 1 chain done, 9 more to go  :)

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