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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

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. Included on-chip are a BCD code-B decoder, multiplex scan circuitry, segment and digit drivers, and an 8x8 static RAM that stores each digit. Only one external resistor is required to set the segment current for all LEDs. The MAX7221 is compatible with SPI™, QSPI™, and MICROWIRE™, and has slew-rate-limited segment drivers to reduce EMI.

A convenient 4-wire serial interface connects to all common µPs. Individual digits may be addressed and updated without rewriting the entire display. The MAX7219/MAX7221 also allow the user to select code-B decoding or no-decode for each digit.

Info from official Maxim's web site

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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 segment display started glitching by displaying…
SmileXS4
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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 70mA for each light. I am using an Arduino to…
Jared Cohen
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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 bright but a little bit bright) and it seems those…
Blundell
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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 the display illuminates all digits and remains…
Andy Preston
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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. I know the MAX7219 is common cathode, so I was…
Scot Kreienkamp
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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 (DIN to MOSI[51th pin], CLK to SCK[52th pin],…
Ekrem Kılıç
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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 it up softly, without these glitches?
zhekaus
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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 works and it does. However from reading the datasheet…
msmith1114
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I want to drive individual LEDs (not a ready made matrix) with a MAX7219 IC

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 out what the specifications of the LEDs need to…
prepzel
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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 daisy chaining from DOUT of previous module to DIN…
Muhammad Ikhwan Perwira
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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 respond to any SPI command turning off and on the…
Mark
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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 buttons all have resistors inside, but they're all…
Dan Forever
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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 is my circuit I use MAX7219 to drive this…
shafiyyah
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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 do a smiley face but the software always show me…
AndyWarholRelive
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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 describes using the chip to drive higher current…
jmg
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