Using an Max7219 to show random data

Using Arduino Displays
1

@marco_c, I have been reading through your forum post, and reading through the examples.

Here is my desired project.

Arduino controlling 6 Max7219 8x8 Matrix LED. Setup in 2 zoned. Modules 0-3 = Z0 and modules 4-5 = Z1.

I am basing off the Parola_Zone_Sign Example.

So far, I have figured out how to create my zones (P.begin and P.setZone). I have also figured out what code makes the display (P.displayZoneText(0, pc[0], PA_CENTER, SPEED_TIME, SPLAT_PAUSE_TIME, PA_PRINT):wink:

I figured out that the array *pc[] is where my messages are displayed. So far, I'm getting all the little nuances figured out.

But, here is my question. I would like to modify the message streams. Here is what I am "thinking", please let me know if I am on the right track. Here is the sketch I have pieced together. It won't compile (still working on aspects, so I have place holders).

//============  Includes / Defines  ============
#include <MD_Parola.h>
#include <MD_MAX72xx.h>
#include <SPI.h>

// Define the number of devices we have in the chain and the hardware interface
#define HARDWARE_TYPE MD_MAX72XX::PAROLA_HW
#define MAX_DEVICES 7
#define CLK_PIN   13
#define DATA_PIN  11
#define CS_PIN    10

#define SPEED_TIME  25
#define SPLAT_PAUSE_TIME  50
#define  TEXT_PAUSE_TIME   1000

#define REAR_DATA_PORT 4
#define FRONT_DATA_PORT 2

// Hardware SPI connection
MD_Parola P = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);


//============  Constants  ============
// --------- Constants ---------
uint8_t frameDelay = 25;  // default frame delay value

// --------- Arrays ---------
char *pc[] = { "\x00f", "Evacuate" };
char *rdp[] = { [rand_data], "Stuff it Wolverine!", [rand_data], "Where's Francis?", [rand_data] };
char *fdp[] = { [rand_data] };

//============  VARIABLES (will change)  ============
uint8_t curText;
uint8_t cycle_count = 0;
// [rand_data] = Random Data - Create random generator

//============  Setup function  ============
void setup(void)
{
  P.begin(2);
  P.setZone(0, 0, REAR_DATA_PORT-1);
  P.setZone(1, REAR_DATA_PORT, MAX_DEVICES-1);


  // All zones
  P.setInvert(false);
  P.setIntensity(4);

  // Specific zones
  P.displayZoneText(0, rdp[cycle_count], PA_CENTER, SPEED_TIME, SPLAT_PAUSE_TIME, PA_PRINT);
  P.displayZoneText(1, fdp[0], PA_CENTER, SPEED_TIME, TEXT_PAUSE_TIME, PA_PRINT);
}

//============  Loop Function  ============
void loop(void)
{
  static uint8_t  inten = 0;
  static int8_t   offset = 1;

  if (cycle_count < 5) {
    cycle_count++;
  } else if (cycle_count >= 5) {
    cycle_count = 0;
  }


  if (P.displayAnimate()) // animates and returns true when an animation is completed
  {
    // Splats
    if (P.getZoneStatus(0)) // in sync with zone 2, so do both
    {
      inten += offset;
      if (inten == 15 || inten == 0)
        offset = -offset;
      P.setIntensity(0, inten);
      P.displayReset(0);
    }

    // Message
    if (P.getZoneStatus(1))
    {
      P.setInvert(1, !P.getInvert(1));
      P.displayReset(1);
    }
  }
}

I am aware that in the zone_sign example, the loop function simply leaves the message alone and animates the message to either invert or flash on and off. I am looking to change the message.

  1. Can I call the P.displayZoneText command in the loop function to change the message?

  2. What is the base format being used for the Asterisk in Z0 and Z2 in the example? I am thinking I can use a random number generator to load the random patterns in that way. Am I correct?

Something else I noticed looking at the Zone_Sign example, the message does not scroll. My desired end result is to scroll the messages and just pop up the random data. However, if that is too much right now, I can work on the scrolling later. That is just a nice add on.

Thank you in advance for your help.

2

I think you need to read the documentation and the blog posts ar ArduinoPlusPlus.

You can everything you list and it is just a matter of understanding the library. For example:

display (P.displayZoneText(0, pc[0], PA_CENTER, SPEED_TIME, SPLAT_PAUSE_TIME, PA_PRINT)

Only prints the message because the method is called with PA_PRINT. Use something else and the display will work differently.

  1. Can I call the P.displayZoneText command in the loop function to change the message?

Yes, This is fundamental as to how Parola works. Lots of the other examples do this and there is plenty about this in the blogs and documentation. The time display example does this, for example.

  1. What is the base format being used for the Asterisk in Z0 and Z2 in the example? I am thinking I can use a random number generator to load the random patterns in that way. Am I correct?

It is just printing the '*' character. You have different options for random stuff. You can use the module in a graphical way by getting the MD_MAX72xx object for the display and just randomly set dots anywhere on the display, or you can define your own character and display that. Covered in the documentation and in at least one example.

I figured out that the array *pc[] is where my messages are displayed.

No, pc[] is where the message are STORED in the example. Parola can display any ascii character string you want as long as you pass this to the library.