SPI communication with MAX7219's cascade connection

[gezgin]

what can I do MAX7219 cascade connection. I connectiong but data stored first MAX7219, others not working.

Code please. May be Proteus project at MicroC wroted.

Thank you ver much for your interesting.

[sawani]

I have this same problem right now. And no one answered to you post! Did you manage some how to solve the problem? If yes, help me please!

[electrocurious]

When Cascading MAX7219's according to the Datasheet use the No-Op register.
if, for example, you have 3 MAX7219 Chips in cascade and you want to send a command to the third chip: here is what you do:
1. Connect all devices’ LOAD/CS inputs together and connect DOUT to DIN on adjacent devices.
2. send the desired 16-bit word, followed by two 16-bit no-op codes (2 pairs of zeros i.e. 0x00)
3. When LOAD/CS goes high, data is latched in all devices. The first 2 chips receive no-op commands, and the third receives the intended data.

I've included working code. i will attach an image as soon as I KNOW HOW to do so

NB: Remember to INITIALIZE all the MAX7219 Chips!!

Here is an Example code that works:

Code: Select all

/****************************************************************************
  *Currency Display System for Banks
  *MikroC code
  *this program shows how to use 3 MAX7219 Chips to Drive 3 8x7 Segment Displays

*****************************************************************************/

int j, dig;
//arrays for content to be displayed. this makes the program flexible!!
int Rands[8] = {0x80,8,5,0x0A,1,0x82,8,2};           //displays 0.85 and 12.82
int Pounds[8] = {0x81,2,5,0x0A, 0x0F, 0x80,9,3};     // displays 1.25 and 0.93
int Pula[8] = {0x87,7,4,0x0A,0x0F,0x80,6,5} ;        //displays 7.74 and 0.65
//0x0A is a dash

// Serial 7-seg Display connections
sbit Chip_Select at RC0_bit;
sbit Chip_Select_Direction at TRISC0_bit;
// End Serial 7-seg Display connections

/*******Initialising MAXes*****************/

//initialise 1st MAX7219
void max7219_init1() {
  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x09);      // BCD mode for digit decoding
  SPI1_write(0xFF);      // using Code-B
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0A);
  SPI1_write(0x0F);      // Segment luminosity intensity
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0B);
  SPI1_write(0x07);      // Display refresh
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0C);
  SPI1_write(0x01);      // Turn on the display
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x00);
  SPI1_write(0xFF);      // No test
  Chip_Select = 1;       // DESELECT MAX
}

//initialise 2nd chip
void max7219_init2() {
  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x09);      // BCD mode for digit decoding
  SPI1_write(0xFF);      // using Code-B
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0A);
  SPI1_write(0x0F);      // Segment luminosity intensity
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0B);
  SPI1_write(0x07);      // Display refresh
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0C);
  SPI1_write(0x01);      // Turn on the display
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x00);
  SPI1_write(0xFF);      // No test
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX
 }
//initialise third chip
void max7219_init3() {
  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x09);      // BCD mode for digit decoding
  SPI1_write(0xFF);      // using Code-B
  SPI1_write(0x00);	 // Bypass the First Chip
  SPI1_write(0x00);
  SPI1_write(0x00);	 // Bypass the Second Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0A);
  SPI1_write(0x0F);      // Segment luminosity intensity
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);	
  SPI1_write(0x00);	 // Bypass the 2nd Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0B);
  SPI1_write(0x07);      // Display refresh
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);
  SPI1_write(0x00);	 // Bypass the 2nd Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x0C);
  SPI1_write(0x01);      // Turn on the display
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);	 
  SPI1_write(0x00);	 // Bypass the 2nd Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX

  Chip_Select = 0;       // SELECT MAX
  SPI1_write(0x00);
  SPI1_write(0xFF);      // No test
  SPI1_write(0x00);	 // Bypass the 1st Chip
  SPI1_write(0x00);
  SPI1_write(0x00);	 // Bypass the 2nd Chip
  SPI1_write(0x00);
  Chip_Select = 1;       // DESELECT MAX
}
/**********End of MAX7219 Initialisation**********/


void main() {

  Chip_Select_Direction = 0;    // Set RC0 pin as output

  SPI1_init();                  // Initialize SPI1 module

  max7219_init1();              // initialize 1st max7219
  max7219_init2();              // initialize 2nd max7219
  max7219_init3();              // initialize 3rd max7219
  
// while(1){

     // Auto Incrementing code for the int array***
     //1st Chip:
     dig = 0;
    for (j=1; j<9; j++) {
          Chip_Select = 0;     // select max7219
          SPI1_write(j);       // send j to max7219 (digit place)
          SPI1_write(Rands[dig]);
          Chip_Select = 1;     // deselect max7219
          dig++;
          }
      //Auto Inc. Ends Here /
      
    // Auto Incrementing code for the int array***
     //2nd Chip:
     dig = 0;
    for (j=1; j<9; j++) {
          Chip_Select = 0;        // select max7219
          SPI1_write(j);          // send j to max7219 (digit place)
          SPI1_write(Pounds[dig]);
          SPI1_Write(0x00);
          SPI1_Write(0x00);      //Bypass 1st chip...
          Chip_Select = 1;       // deselect max7219
          dig++;
          }
      //Auto Inc. Ends Here /
      
     // Auto Incrementing code for the int array***
     //3rd Chip:
     dig = 0;
    for (j=1; j<9; j++) {
          Chip_Select = 0;         // select max7219
          SPI1_write(j);          // send j to max7219 (digit place)
          SPI1_write(Pula[dig]);
          SPI1_Write(0x00);       //Bypass 1st Chip
          SPI1_Write(0x00);
          SPI1_Write(0x00);       //Bypass 2nd Chip
          SPI1_Write(0x00);
          Chip_Select = 1;        // deselect max7219
          dig++;
          }
      //Auto Inc. Ends Here /
      
 //     }

}

[electrocurious]

Before I forget, Special Thanks to ducu for the initial MAX7219 code.