LED strip and SD card

Question

My problem is simple yet extremely problematic. For some reason, I cannot interact with an SD card and a LED strip at the same time with my arduino. After hours of testing multiple scripts, I am 99.99% that the issue is due to the SPI.h library. I have tried the simplest LED strip code, such as turning on led number 5. If I include SPI.h, the code does not work, the data LED of the arduino doesn't even light up, the arduino doesn't send anything to the strip data line. If I remove include SPI.h, the code works. This is really odd, I have read about the SPI.h messing with the pins, so now I'm looking for a solution, to use the SD card module without the SPI library if it is possible. Here is an example of a code that does not work due to the use of the SPI.h library.

Any help is greatly appreciated, this is extremely odd and problematic.

#include <Time.h>
#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
#include <avr/power.h>
#endif
#include <SPI.h>
#include <SD.h>

Sd2Card card;
SdVolume volume;
SdFile root;

const int chipSelect = 4;

#define PIN            6
#define NUMPIXELS      400

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB +   NEO_KHZ800);

boolean stringComplete = false;  // whether the string is complete
boolean readarray=false;
String inString = "";
int c=0;
int cc=0;
int led=0;
int i=0;
int j=0;
int pixel_n=0;
unsigned long start;
unsigned long endd;

//char* ledd[]={"", "", ""};
int ledd[3]={0,0,0};

File myFile;

void setup()
{
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
pixels.begin();
while (!Serial) {
  ; // wait for serial port to connect. Needed for Leonardo only
}


Serial.print("\nInitializing SD card...");

// Now we will try to open the 'volume'/'partition' - it should be FAT16 or FAT32
if (!volume.init(card)) {
  Serial.println("Could not find FAT16/FAT32 partition.\nMake sure you've formatted the card");
  return;
}


// print the type and size of the first FAT-type volume
uint32_t volumesize;
Serial.print("\nVolume type is FAT");
Serial.println(volume.fatType(), DEC);
Serial.println();


Serial.println("Ok we're done");
delay(2000);


pixels.setPixelColor(5, (200,200,200)); // THIS DOES NOT WORK
pixels.show(); // THIS EITHER

  Serial.begin(9600);
}


void loop(void) {

}

Answer 1

I had the same problem with using the SD reader with a SPI SRAM. It turns out that the very cheap SD reader cards do not like multiple SPI components on the same port. Since the Arduino has only one SPI, the only thing that worked was to use a SD data logger card.

To add a tristate solution by using two resistors on the MISO line also did not work in my case.

See my post for the post I created regarding this probably similar problem.