Questions tagged [max7219]

Refers to the MAX7219 chip, a multiplexing LED driver. Use this tag for discussing the MAX7219 chip.

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Max7219 7-segment display not working

when I connect VCC pin to the 5V and GND to the GND on the Arduino MEGA, then sometimes the display glows and sometimes it doesn't. It kinda looks like some contacts are bad because it starts to work ...
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79 views

ESP8266 NODEMCU V3 web server with MAX7219 and DS3231 RTC

I am using ESP8266 NodeMCU with MAX7219 and a DS3231 teal time clock. I want to display the time and some text. The display is made of 4 FC16 modules which are made of 4 8x8 MAX7219 led matrix modules ...
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182 views

Parola library and DS3231 clock

EDIT2: Well, this is the "new" code and it just displays random dots on the matrices: #include "RTClib.h" #include <MD_Parola.h> #include <MD_MAX72xx.h> #include <SPI.h> // Define ...
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104 views

FC-16 led matrix module based on MAX7219

EDIT: const char *pc[NUM_ZONES] = { "ROOM", //0 "SUBJECT", //1 "GRADE",//2 }; I did this and I can't get them to display every row simultaneously. void loop(void) { DateTime now = rtc....
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25 views

DS3231 clock module with cascaded FC-16 led matrix modules + Arduino Nano

I am using a DS3231 real time clock module and 4 cascaded FC-16 modules(they are basically MAX7219 led matrices based modules). My goal is to display a timetable, a schedule for a classroom on the ...
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1answer
125 views

Arduino Nano, DS3231 RTC clock module and 4 cascaded FC-16 led matrix modules

Like I said in the title, I am using a DS3231 real time clock module and 4 cascaded FC-16 modules(they are basically MAX7219 led matrices based modules). My goal is to display a timetable, a schedule ...
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1answer
38 views

MAX7219 with 8digit 7seg array

I have a concern about the library port handling. I have used direct port direction manipulation successfully in previous projects but there seems to be a problem here. // This code mostly taken from ...
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1answer
214 views

Scroll Left to Right on MAX7219 Display

For scrolling from left to right (Arabic letters) I need a function to print words/sentences on the MAX7219 display. [By setpixel(x, y) function] I did a lot of searching and my efforts failed. I ...
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2answers
294 views

Daisy chaining of multiple blocs of 4x(8x8) MAX7219 matrix

Thanks for your presentation https://arduino.stackexchange.com/tags/max7219/info. You say that multiple MAX7219 8x8 blocs can easily be daisy-chained and you show an example of at least 12 blocs ...
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2answers
468 views

Making a timer accurate to 1 millisecond possible? Using MAX7219 LED

I'm using the Max7219 (8 digits, 7bits) led display to try and make a timer. I have downloaded an example code from the following site to set the led digits: https://www.brainy-bits.com/arduino-...
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56 views

MAX7219 only displaying on first digit

I'm trying to display a scrolling number on my MAX7219 display using the LedControl library, but can only ever get the first digit (digit 0) updating. When I reference digits 1-7 the 7 segments don't ...
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327 views

MAX7219 Does Not Light Up Using Wemos D1 Mini ESP8285 Lite

This is my first time posting, so I apologize if this is in the wrong place. I'm trying to build my first Arduino project that shows monthly revenue from Stripe's REST API using a Wemos D1 Mini ...
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1answer
43 views

Using an Android bluetooth terminal to change preset states on 8x8 LED matrixes

I'm trying to create eyes for a project, and while I have been able to properly program the different expressions, and have them triggered by commands from the COM3 terminal, I have not been able to ...
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1answer
257 views

MAX7219 and Arduino

I am getting started in running this 8x8 led on an Arduino. Regardless of which tutorial sketch I attempted, I never got a scrolling text that I expect. What happens seems to be only a single (out of ...
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3answers
820 views

SPI Wiring Confusion

I am currently trying to learn about SPI and how it works on the Arduino. I want to wire a MAX7219 chip to it to drive an 8x8 LED matrix with. Normally, I would assume the wiring from Arduino to ...
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65 views

Losing value of variable

I am making a project involving the AutoConnect, ArduinoJSOn and LedControl libraries to fetch some values from an endpoint. Basically what I do is connect to the internet, fetch the values from a ...
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1answer
141 views

Upload data to MAX 7219

I have the following code to write data on MAX7219 for light up a 8x8 LED Matrix: for (i = 0; i < 8; i++) { CLK = LOW; DIN = temp & MSBIT >> i; CLK = ...
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2answers
3k views

Difference between 3.3v & 5v

Im quite new to arduino in general and i'm sorry for the beginner question. could someone explain what the 3.3v and 5v on boards do? I know their voltages. but can you run one on the other? whenever ...
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2answers
509 views

Random LEDs light up on 10 MAX7219 modules

I'm trying to create an IoT clock using 10 MAX7219 (Serially Interfaced, 8-Digit, LED Display Drivers) modules. I've created the following code: //clock.ino #define MODULES_X 5 #define MODULES_Y 2 #...
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3answers
572 views

How to drive SPI MAX7219 7-segment led module using MCP23S17 extender

I have used Nick Gammon's (MAX7219) and (bitBangedSPI) libraries to drive SPI 7-segment 8 digit led modules successfully from the Arduino Uno. I would like to extend the number of Slave Select (CS) ...
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1answer
443 views

Need help with using LED matrix with pushbuttons

I am building a small project that uses a pair of 8x8 LED matrix (driven by the MAX7219), a pair of SG90 servos, a HC-SR04 ultrasonic sensor, a 16x2 LCD (Hitachi HD44780 driver), some push buttons and ...
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1answer
30 views

Tinyduino I/O line voltage level

Does anyone know what the I/O line voltage level is on the Tinyduino? Tinyduino I want to run a MAX7219 LED array with it, like this one: LED Array
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1answer
685 views

MAX7219 library that can compensate for poorly designed/miswired 8x32 panel?

I have this sample code: #include <MD_Parola.h> #include <MD_MAX72xx.h> #include <SPI.h> #define MAX_DEVICES 4 #define CLK_PIN 11 #define DATA_PIN 12 #define CS_PIN 10 ...
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1answer
1k views

MAX7219 7-segment 8-digit display in wrong order

I have daisy-chained three MAX7219 7-segment 8-digit displays and wired it according to this diagram: but no matter what library I use, the middle segment is in the wrong order when I display it. So ...
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1answer
1k views

MAX7219 with Arduino UNO - LED control doesn't work

I'm very new to Arduino and this is my first project, so I may misunderstand something simple. As a hardware I'm using 4 MAX7219 connected to Arduino UNO and a single diod for tests. As a software I ...
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2answers
541 views

MAX7219 powered on via digital pin set to HIGH is not working good (I < 25mA)

I'm using 7-segment 8-digits MAX7219 eBuy module in my battery-supplied ATMega168P project to output some readings. MAX7219 in powerdown mode draws ~150uA (as stated in the datasheet) which is too ...
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3answers
470 views

MAX7219 not behaving as expected

I have 2 rows of 12 MAX7219 connected in series with DOUT to DIN (rows are isolated). Now the thing is I am using LedControl Library to work with it. The problem is the last 4 Matrices on both the ...
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3answers
807 views

Why do the LEDs visibly flicker?

The aim of the project was to be able to show two "kinds" of LEDs in a 8x8 single color LED matrix. I used a MAX7219 chip to drive the LEDs using my Arduino UNO R3 as the driver (with the usual ...
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2answers
675 views

ISR and multiplexing- time required to execute the code in Arduino

Below is an Arduino sketch for a basic animation, taken from the book Beginning Arduino by Michael McRoberts. Also, the connections have been shown. From what I have read elsewhere, this is the ...
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4answers
10k views

max7219 chained display showing mirrored text

I'm using a max7219 like this one max7219. When I first tested my circuit, I used an 8x8 display and the code worked just fine. Now, after I modified the code with the one that can be found online at ...
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0answers
147 views

How to drive RGB LED fading alongside MAX7219s

Merry XMAS I have a pro mini which drives 2 RGB LED strips on its 6 PWM pins, via 6 2N7000 N-channel MOSFETs. Alongside these, I have 4 x MAX7219 modules in series controlled via SPI. Both work ...
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1answer
642 views

max7219 chained display showing text only on the first display

I'm using a max7219 like this one max7219. When I first tested my circuit, I used an 8x8 display and the code worked just fine. Now, after I modified the code and changed the display with the chained ...
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0answers
403 views

Arduinino & Max7219

I'm using a MAX7219 and 6 (six) seven segment displays I used my own board and two purchased on ebay - no difference in operation. MOSI, and CLK are correct and verified with my scope (Tektronics) CS (...
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1answer
250 views

Power 4 leds with max7219 and LedControl.h

So this is my first arduino (or embedded for that matter) project. I am trying to power 4 leds with max7219. Max7219 seems easy to use, but for some reason after I upload the code, nothing happens. I'...
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3answers
641 views

8x8 solenoid matrix

I've been teaching a blind student how to program and build electronics with Arduino. So far I've substituted LED's with piezo buzzers with excellent results. We are getting to the point where more ...
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1answer
5k views

Arduino Uno powers off when circuit plugged in to +5V and GND pins

I have a max7219 driving an 8 digit 7 segment LED array with forward current of 20mA and typical forward voltage of 1.85V. I'm trying to power this through my arduino UNO (which itself is drawing ...
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1answer
3k views

Fading the brightness of LEDs using MAX7219 and PWM

I am doing a project with bi-color led matrix 8x8 and MAX7219 as the LED driver. I want to implement a fading effect on the LEDs, like mixing the two colors by varying the individual duty cycles. My ...