Questions tagged [max7219]

The MAX7219/MAX7221 are compact, serial input/output common-cathode display drivers that interface microprocessors (µPs) to 7-segment numeric LED displays of up to 8 digits, bar-graph displays, or 64 individual LEDs

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When using MAX7219, I am having trouble because the LED is dark

I have attached the image. When power is connected to LED A, 20 mA will flow at 100R. This is not a problem. It shines brightly. On the other hand, the output of the MAX7219 draws only 4 mA when LED B ...
M MODELER's user avatar
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MAX7221 with multiple LEDs per point

I am using a MAX7219/MAX7221 chip in a keyboard design in order to light up the individual keys. The keyboard is going to have exactly 64 keys so with the 8x8 matrix the chip handles I will be able to ...
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Can I use a MAX7219/7221 chip to drive 16 common anode RGB LEDs?

I am using a MAX7219 to attempt to power 16 common anode RGB LEDs. The MAX 7219 has a resistor which must be wired in series with its ISET pin in order to set the current per segment of the IC, as per ...
kiryakov's user avatar
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Trouble driving 4 digit LED display with a MAX7219 display driver and a PIC16F690 MCU

I am attempting to drive a 4 digit, common cathode LED display with a MAX7219CNG display driver and a PIC16F690 MCU for SPI communication. The LED display does not light up and appears to not be ...
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I want to drive individual LEDs (not a ready made matrix) with a MAX7219 IC [closed]

I want to control 24 single LEDs with a MAX7219. I understand the concept of the matrix and I know how to control the MAX7219. What I don't understand is how to read the datasheet correctly and work ...
prepzel's user avatar
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4 answers
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SPI signal noisy when contactor switches

I created a Raspberry Pico based PLC board which worked perfectly alone, however once I placed it into a distribution box and started switching a fairly large (7.5kW) contactor, the on-board seven ...
SmileXS4's user avatar
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Should I continue use daisy chaining or use another Chip Select PIN in MAX7219 8×8 LED matrix module to increase height dimension?

Consider I have 4 daised chaining of MX7219 LED Matrix 8×8. Thats mean i have more width than height (32×8) or (width×height) If i want improve overal width of LED again, thats mean i must continue ...
Muhammad Ikhwan Perwira's user avatar
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Can I drive a common anode multiplex display with MAX7219?

I am trying to integrate with a pre-existing common-anode 3 digit, 7 segment LED panel (spoiler, it's a jukebox wallbox custom conversion) using a MAX7219, which will be controlled by a Raspberry Pi. ...
Scot Kreienkamp's user avatar
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MAX7221 always hangs on first power on

I have an issue quite similar to this one. The behavior of my MAX7221 is the following: when powering on the board the first time (let's from cold & dark) it turn on all the segments and does not ...
Mark's user avatar
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What happens if there's no resistor before the ISET pin of a MAX7219 LED driver chip?

I have a bunch of spst-no buttons each with an led inside. I've just hooked them up to a MAX7219 and they are very dim (when hooked up directly to the microcontroller they're fine). My guess is the ...
Dan Forever's user avatar
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Slow turn-off time on PNP when driving 7 segment led

I know that there has already been question about optimizing PNP turn-off time, but my circuit is a bit different from that question so the solution presented there does not seem to work for me. Here ...
shafiyyah's user avatar
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STM32 Matrix LED 8x8 Display using SPI Interface with MAX7219 in Proteus Simulation

I was trying to do a project in Proteus Desing Suite which needs to use a Matrix LED Display with size of 8x8 using MAX7219 SPI Interface. The problem occurs when I try to simulate it. I'm trying to ...
AndyWarholRelive's user avatar
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1 answer
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MAX7219 Entering Test Mode and Displaying Random Characters

I'm using MAX7219 with 6 common cathode 38mm (each segment has 2 red LEDs except DP) 7-segments controlled by Arduino Mega2560. I have connected MAX7219 and the board as stated in MAX7219's datasheet (...
Ekrem Kılıç's user avatar
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Max7219 and Common Anode Displays, choosing the correct transistors

I've got some common anode 7 Segment displays that I want to use a Maxim 7219 IC to drive with. The Max7219 is designed for direct driving common cathode displays but Maxim do have an app note that ...
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How to use MAX7219 with high current LEDs

I am fairly new to electronics. I am using the MAX7219 to control an led matrix and the data sheet for the MAX7219 says that the maximum current each light can get is 40mA, but for my purpose I need ...
Jared Cohen's user avatar
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MAX7219 led matrix prints unwanted artifacts when it is powered up

I’ve got Led matrix 32x8 which is driven by MAX7219. Like this: MAX7219 Dot Matrix Module Microcontroller 4 In One Display with 5P Line When I power it up, I can see different glitches. How to power ...
zhekaus's user avatar
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LED Matrix creation using resistors & MAX7219

I've been attempting to create my own LED matrix, but now I've plugged it all together I'm getting some unexpected LED's lighting up, it seems some are getting power when they shouldn't (not very ...
Blundell's user avatar
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How to interpret MAX7219 timing diagram?

I'm trying to connect this module to atmega32u4 (16 MHz): Everything seems mostly working, but I have a question: how much time is needed for the latch to take effect? I.e., is a delay needed between ...
Igor Liferenko's user avatar
1 vote
2 answers
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MAX7219, SPI capable/Timing question?

So I purchased a cheap Double-7-Segment display piece (specifically this one: https://www.amazon.com/dp/B01D0WSCJA) To do some tinkering with. I've messed around with it manually to make sure it ...
msmith1114's user avatar
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7-Segment Drivers: How do they work/how to handle them?

So I know to drive a 7-segment display you need a TON of pins. However there are 7-segment display drivers (such as the MAX7219) that seem pretty popular. However I'm looking at the datasheet, and am ...
msmith1114's user avatar
2 votes
0 answers
385 views

MAX7221 not always powering on

I have a MAX7221 SPI 7-seg. LED driver linked to an AVR168P microcontroller. Sometimes when powering on, everything works as expected. Other times the display blanks and remains blank. Other times ...
Andy Preston's user avatar