Hi all, this is the first time posting on this forum, so I apologize if this is in the wrong category. I'm also very new to the Arduino scene, and hardware in general, so I may not be familiar with all the lingo yet.
I am building a "clock" that will display Stripe revenue from their API. I have written the code for this and it works great in the Serial output, however, I can't for the life of me to get the MAX7219 to work. I am working with the MAX72XX library.
This is my current hardware:
Wemos D1 Mini Lite (https://www.amazon.com/gp/product/B07BK435ZW/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1)
MAX7219 https://www.amazon.com/gp/product/B07FFV537V/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
Jumper Wires https://www.amazon.com/gp/product/B077N5RLHN/ref=ppx_yo_dt_b_asin_title_o01_s02?ie=UTF8&psc=1
Breadboard https://www.amazon.com/gp/product/B01EV6SBXQ/ref=ppx_yo_dt_b_asin_title_o01_s02?ie=UTF8&psc=1
This is my current configuration:
Wemos D5 -> MAX7219 CLK
Wemos D7 -> MAX7219 DIN
Wemos D8 -> MAX7219 CS
Wemos GND -> MAX7219 GND
Wemos 5V -> MAX7219 VCC
I have configured it this way from following the pin layout from this URL:
https://wiki.wemos.cc/products:d1:d1_mini_lite
My board configuration:
LOLIN(WEMOS) D1 mini Lite, 80 MHz, Flash, 1M (no SPIFFS), v2 Lower Memory, Disabled, None, Only Sketch, 921600 on /dev/cu.wchusbserial1420
Additionally, this is the code that I am using (Example from MAX72XX library):
// 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::PAROLA_HW
#define MAX_DEVICES 4
#define CLK_PIN D5 // or SCK
#define DATA_PIN D7 // or MOSI
#define CS_PIN D8 // 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 scrolling 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;
}
}
When I run this code, it compiles and uploads just fine. I can even see the serial output telling me to "write a new message", and yet nothing happens on the LEDs.
I'm not sure if this is relevant, but if I shimmy the USB out, sometimes all the LEDs will light up at full brightness.
I also have two of every part, and have tried each one to no avail, so I do not believe it is a faulty part.
If anyone has any feedback or ideas I would be glad to hear them. I have researched for this issue but couldn't find anything. I also posted on the Arduino Stack Exchange but had no luck there as well.
I realize the more information the better, so if I left anything out I would be happy to add it.
Here are some images of the components:
Thanks for any advice!
