RGB Backpack daisy chain question

Development Boards MicroMod
1

okay, so I’m a bit confused - adding the following function should enable daisy chaining on the RGB Backpack for “x” number of matrix’s, however, it doesn’t seem to be working - any suggestions?

Forgot to mention I’m using an Arduino.

void daisyChain(int matrix)
{
  digitalWrite(CHIPSELECT,LOW); // enable the ChipSelect on the backpack
  delayMicroseconds(500);

  spi_transfer('%');
  spi_transfer(matrix);

  digitalWrite(CHIPSELECT,HIGH); // disable the ChipSelect on the backpack
  delayMicroseconds(500);
}
2

Hi There,

Ok, first of all how many boards are you trying to daisy chain? What is matrix set to? Is it an integer or a character?

Now for the important part. If your SPI transfer function is set up correctly, then you’ll still need to hook each board up to the Arduino individually and run that set up procedure. If you just daisy chain all of the boards and then send that command only the first board in the system will be programmed.

Does this make sense?

Good Luck!

3

I am trying to daisy chain 4 boards together, I set up the function daisyChain that takes (int matrix) so that I could easily change the number of boards in the chain. And yes, I did attempt to run this on each board individually before chaining them together.

However when I have the boards together, I only get jumbled pixels here and there.

EDIT: Okay, I partially solved the problem, it seems that since I was using 2 power supplies to power the arduino, and matrix’s I needed to tie the grounds together. Now I get a definable image (a heart), however, it is shifted to the left by +1 pixel on every matrix.

Here is the complete code I am using.

#define CHIPSELECT 10//ss
#define SPICLOCK  13//sck
#define DATAOUT 11//MOSI
#define DATAIN 12//MISO

int color = 1;
int count = 1;
long randNum;

int data[] =
{
  0,0,0,0,0,0,0,0,
  0,0,64,64,0,64,64,0,
  0,64,0,0,64,0,0,64,
  0,64,0,0,0,0,0,64,
  0,0,64,0,0,0,64,0,
  0,0,0,64,0,64,0,0,
  0,0,0,0,64,0,0,0,
  0,0,0,0,0,0,0,0
};


========================================================================================
void setup()
{
  byte clr;
  pinMode(DATAOUT,OUTPUT);
  pinMode(SPICLOCK,OUTPUT);
  pinMode(CHIPSELECT,OUTPUT);
  digitalWrite(CHIPSELECT,HIGH); //disable device

  //SPI Bus setup
  SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR1);	//Enable SPI HW, Master Mode, divide clock by 16  
  delay(10);

  //daisyChain(4); // let the backpack know that it is in a chain of "x" matrix's

}


========================================================================================
void loop()		
{
  digitalWrite(CHIPSELECT,LOW); // enable the ChipSelect on the backpack
  delayMicroseconds(500);


for(int n=0;n<4;n++)   
{
  for (int x=0;x<64;x++) // Send pre-built array
  {
    spi_transfer(data[x]);
  }
}


  digitalWrite(CHIPSELECT,HIGH); // disable the ChipSelect on the backpack
  delayMicroseconds(500);
  delay(1000);
}

========================================================================================
char spi_transfer(volatile char data)
{
  SPDR = data;			  // Start the transmission
  while (!(SPSR & (1<<SPIF)))     // Wait the end of the transmission
  {
  };
}


========================================================================================
void daisyChain(int matrix)
{
  digitalWrite(CHIPSELECT,LOW); // enable the ChipSelect on the backpack
  delayMicroseconds(500);

  spi_transfer('%');
  spi_transfer(matrix);

  digitalWrite(CHIPSELECT,HIGH); // disable the ChipSelect on the backpack
  delayMicroseconds(500);
}

And this is the output…

http://cse.secs.oakland.edu/~srcasade/RGB.JPG