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Questions tagged [max7219]

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

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1answer
18 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
45 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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1answer
92 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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0answers
32 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
55 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
525 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
272 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
276 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
175 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
25 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
480 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
680 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
716 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
364 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
341 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
501 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
463 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
5k 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
112 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
437 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
324 views

Arduinino & Max7219

Im 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
232 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
482 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
4k 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
2k 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 ...