3

I am new to arduino and have a sparkfun pro micro that I'm using to power a one meter (60 pixels) APA 102 strip. I currently power it via USB and have a program that sends lighting instructions to it. I can only seem to power ~15 pixels with full range of brightness and ~30 if I keep the brightness at about half.

Anything more and the pro micro will stop recieving data and either freeze at the last color it's recieved or turn a bright red (which I assume is a visual indication of the fail because I didn't code that). At this point, the COM port will also become inaccessible until the code is either re-uploaded or in some cases, I simply disconnect the strip. This leads me to believe that the amount of power that I am demanding is too much for the board to put out.

So am I right in this assumption? and If so, what can I do to increase the amount of pixels I can power at full range?

I'll also post my code below in case there is something I can do there to increase the pixel amount:

#include <Adafruit_DotStar.h>
#include <SPI.h>

#define NUMPIXELS 60
#define DATAPIN    4
#define CLOCKPIN   5

Adafruit_DotStar strip(NUMPIXELS, DOTSTAR_BRG);

// Variables
int mode;
int numColors;
int fadeSpeed;
int BBCC;
int R;
int G;
int B;
int Bright;

void setup() {

#if defined(__AVR_ATtiny85__) && (F_CPU == 16000000L)
  clock_prescale_set(clock_div_1); // Enable 16 MHz on Trinket
#endif

  strip.begin(); // Initialize pins for output
  strip.show();  // Turn all LEDs off ASAP
}

int      head  = 0, tail = -10; // Index of first 'on' and 'off' pixels
uint32_t color = 0xFFFFFF;      // 'On' color (starts red)

void loop() {

  //strip.setPixelColor(head, color); // 'On' pixel at head
  //strip.setPixelColor(tail, 0);     // 'Off' pixel at tail
  strip.show();                     // Refresh strip
  delay(20);                        // Pause 20 milliseconds (~50 FPS)

  getData();

  if (mode == 1)
  {
    for (int i = 0; i < (60); i++)
    {
      if (i % 2 == 0)
        strip.setPixelColor(i, G, R, B);
    }
    strip.setBrightness(Bright);
    strip.show();
  }
  else
  {
    for (int i = 0; i < (60); i++)
    {
      if (i % 2 == 0)
        strip.setPixelColor(i, 150, 200, 40);
    }
    strip.setBrightness(255);
    strip.show();
  }
}

int readLine(int readch, char * buffer, int len)
{
  static int pos = 0;
  int rpos;

  if (readch > 0)
  {
    switch(readch)
    {
      case '\r':
      {
        break;
      }
      case '\n':
      {
        rpos = pos;
        pos = 0;
        return rpos;
      }
      default:
      {
        if (pos < len-1) 
        {
          buffer[pos++] = readch;
          buffer[pos] = 0;
        }
      }
  }

  return 0;
}
}

void getData()
{
  char buf[80];
  bool redo = true;

  if(readLine(Serial.read(), buf, 80) > 0)
  {
    int i = 0;
    int j = 0;
    bool skip = false;
    char fin[3];
    if (skip == false)
    {
    do//                                mode
    {
      switch (buf[i])
      {
        case '\n':
        {
          skip = true;
          redo = false;
          break;
        }
        case '|':
        {
          mode = atoi(fin);
          //Serial.print(mode);
          i++;
          redo = false;
          break;
        }
        default:
        {
          fin[j] = buf[i];
          i++;
          break;
        }
      }
      j++;
    }while(redo);
    redo = true;
    j = 0;
    }



    if (skip == false)
    {
    do//                     number of colors
    {
      switch (buf[i])
      {
        case '\n':
        {
          skip = true;
          redo = false;
          break;
        }
        case '|':
        {
          numColors = atoi(fin);
          //Serial.print(numColors);
          i++;
          redo = false;
          break;
        }
        default:
        {
          fin[j] = buf[i];
          i++;
          break;
        }
      }
      j++;
    }while(redo);
    redo = true;
    j = 0;
    }



    if (skip == false)
    {
    do//                            
    {
      switch (buf[i])
      {
        case '\n':
        {
          skip = true;
          redo = false;
          break;
        }
        case '|':
        {
          fadeSpeed = atoi(fin);
          //Serial.print(fadeSpeed);
          i++;
          redo = false;
          break;
        }
        default:
        {
          fin[j] = buf[i];
          i++;
          break;
        }
      }
      j++;
    }while(redo);
    redo = true;
    j = 0;
    }



    if (skip == false)
    {
    do
    {
      switch (buf[i])
      {
        case '\n':
        {
          skip = true;
          redo = false;
          break;
        }
        case '|':
        {
          BBCC = atoi(fin);
          //Serial.print(BBCC);
          i++;
          redo = false;
          break;
        }
        default:
        {
          fin[j] = buf[i];
          i++;
          break;
        }
      }
      j++;
    }while(redo);
    redo = true;
    j = 0;
    }



    if (skip == false)
    {
    do
    {
      switch (buf[i])
      {
        case '\n':
        {
          skip = true;
          redo = false;
          break;
        }
        case '|':
        {
          R = atoi(fin);
          //Serial.print(R);
          i++;
          redo = false;
          break;
        }
        default:
        {
          fin[j] = buf[i];
          i++;
          break;
        }
      }
      j++;
    }while(redo);
    redo = true;
    j = 0;
    }



    if (skip == false)
    {
    do
    {
      switch (buf[i])
      {
        case '\n':
        {
          skip = true;
          redo = false;
          break;
        }
        case '|':
        {
          G = atoi(fin);
          //Serial.print(G);
          i++;
          redo = false;
          break;
        }
        default:
        {
          fin[j] = buf[i];
          i++;
          break;
        }
      }
      j++;
    }while(redo);
    redo = true;
    j = 0;
    }



    if (skip == false)
    {
    do
    {
      switch (buf[i])
      {
        case '\n':
        {
          skip = true;
          redo = false;
          break;
        }
        case '|':
        {
          B = atoi(fin);
          //Serial.print(B);
          i++;
          redo = false;
          break;
        }
        default:
        {
          fin[j] = buf[i];
          i++;
          break;
        }
      }
      j++;
    }while(redo);
    redo = true;
    j = 0;
    }



    if (skip == false)
    {
    do
    {
      switch (buf[i])
      {
        case '\n':
        {
          Bright = atoi(fin);
          //Serial.println(Bright);
          i++;
          redo = false;
          break;
        }
        default:
        {
          fin[j] = buf[i];
          i++;
          break;
        }
      }
      j++;
    }while(redo);
    redo = true;
    j = 0;
    }
  }
}
4

As Majenko already mention, use a separate power supply.

  • Use that power to power the LED strip(s).
  • Use the MCU to control the data and clock lines.
  • Connect grounds together.
  • MCU? I'm really new so I don't know what that is. I'm using the SCK and MISO pins. Is that the same thing? – BoatHouse Aug 15 at 13:59
  • 1
    An MCU is a Micro Controller Unit, your Arduino is one (example of an ) MCU. The SCK is the clock line (Serial Clock) and MISO (Master In Slave Out) are data lines. If you google for SPI you will find out what SCK and MISO are meant for. – Michel Keijzers Aug 15 at 14:03
3

Managing your power budget is a normal part of electronics projects. You can only draw about 500 mA total from the USB port, and less than that from the 5V line if your Arduino is powered from USB. If you drive your Arduino with ≈7V into the barrel connector you might be able to pull a full amp from the 5V rail, but it depends on how hot the voltage regulator gets. The higher the input voltage into the regulator, the more heat you generate for a given amount of current. On a genuine Arduino board the voltage regulator should have an overheat protection circuit, which will cause it to shut off when it gets too hot. Cheap knockoffs may just burn out.

When you start using higher current devices like motors or LED strips, it's usually a good idea to switch to a separate (regulated) power supply for those devices. Tie the ground lines together, and since you use separate power supplies for the Arduino and your other devices, they don't affect each other's supply voltages.

2

So am I right in this assumption?

Yep.

and If so, what can I do to increase the amount of pixels I can power at full range?

Simple: don't power it from the Arduino. Add a proper external power supply that is capable of providing the current you require.

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