Thank you all for your reply. Hopefully I can answer all your questions. In doing so, did not reply to each person, figuring it's best to reply in the post.....is that correct?
Here are my responses:
(1) The weblink for the specific MAX7219 item I have is:
(2) I'm assuming (?) the displays are not incorrectly rotated 180 degree since I tried both units as purchased right out of the package.
(3) I was asked for my wiring schematic, photo of hardware and full sketch code.
I tried to attach 1 schematic and 4 photos, but when trying to post it said as a new user I am only allowed One upload attachment, so I chose the Schematic. Didn't know what esle to do.
I saved the code using "copy for forum" and will paste it here:
// Use the MD_MAX72XX library to Print some text on the display
//
// Demonstrates the use of the library to print text.
//
// User can enter text on the serial monitor and this will display as a
// message on the display.
#include <MD_MAX72xx.h>
#include <SPI.h>
#define PRINT(s, v) { Serial.print(F(s)); Serial.print(v); }
// Define the number of devices we have in the chain and the hardware interface
// NOTE: These pin numbers will probably not work with your hardware and may
// need to be adapted
#define HARDWARE_TYPE MD_MAX72XX::FC16_HW
#define MAX_DEVICES 4
#define CLK_PIN 13 // or SCK
#define DATA_PIN 11 // or MOSI
#define CS_PIN 10 // or SS
// SPI hardware interface
MD_MAX72XX mx = MD_MAX72XX(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);
// Arbitrary pins
//MD_MAX72XX mx = MD_MAX72XX(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);
// Text parameters
#define CHAR_SPACING 1 // pixels between characters
// Global message buffers shared by Serial and Scrolling functions
#define BUF_SIZE 75
char message[BUF_SIZE] = "Hello";
bool newMessageAvailable = true;
void readSerial(void)
{
static uint8_t putIndex = 0;
while (Serial.available())
{
message[putIndex] = (char)Serial.read();
if ((message[putIndex] == '\n') || (putIndex >= BUF_SIZE-3)) // end of message character or full buffer
{
// put in a message separator and end the string
message[putIndex] = '\0';
// restart the index for next filling spree and flag we have a message waiting
putIndex = 0;
newMessageAvailable = true;
}
else
// Just save the next char in next location
message[putIndex++];
}
}
void printText(uint8_t modStart, uint8_t modEnd, char *pMsg)
// Print the text string to the LED matrix modules specified.
// Message area is padded with blank columns after printing.
{
uint8_t state = 0;
uint8_t curLen;
uint16_t showLen;
uint8_t cBuf[8];
int16_t col = ((modEnd + 1) * COL_SIZE) - 1;
mx.control(modStart, modEnd, MD_MAX72XX::UPDATE, MD_MAX72XX::OFF);
do // finite state machine to print the characters in the space available
{
switch(state)
{
case 0: // Load the next character from the font table
// if we reached end of message, reset the message pointer
if (*pMsg == '\0')
{
showLen = col - (modEnd * COL_SIZE); // padding characters
state = 2;
break;
}
// retrieve the next character form the font file
showLen = mx.getChar(*pMsg++, sizeof(cBuf)/sizeof(cBuf[0]), cBuf);
curLen = 0;
state++;
// !! deliberately fall through to next state to start displaying
case 1: // display the next part of the character
mx.setColumn(col--, cBuf[curLen++]);
// done with font character, now display the space between chars
if (curLen == showLen)
{
showLen = CHAR_SPACING;
state = 2;
}
break;
case 2: // initialize state for displaying empty columns
curLen = 0;
state++;
// fall through
case 3: // display inter-character spacing or end of message padding (blank columns)
mx.setColumn(col--, 0);
curLen++;
if (curLen == showLen)
state = 0;
break;
default:
col = -1; // this definitely ends the do loop
}
} while (col >= (modStart * COL_SIZE));
mx.control(modStart, modEnd, MD_MAX72XX::UPDATE, MD_MAX72XX::ON);
}
void setup()
{
mx.begin();
Serial.begin(57600);
Serial.print("\n[MD_MAX72XX Message Display]\nType a message for the display\nEnd message line with a newline");
}
void loop()
{
readSerial();
if (newMessageAvailable)
{
PRINT("\nProcessing new message: ", message);
printText(0, MAX_DEVICES-1, message);
newMessageAvailable = false;
}
}
Zf.jpeg)51
It has been moved to a more suitable location on the forum.
) using a Mega 2560 whose hardware is different.
