0
\$\begingroup\$

I have an Arduino Uno, using a MAX7219 to control a 8x8 Bi-color led matrix.

The problem however, is that upon activating a 5th led in the matrix, the unit "dies", in lack of a better word. I can activate any arbitrary combination of 4 leds, but upon the activation of a fifth, the matrix flashes promptly and goes blank.

What kind of problem does this sound like? Improper resistor value? Grounding or inadequate power?

UPDATE: Upon disconnecting the wire grounding the breadboard to the Arduino, all the desired leds are lighting up in my expected pattern, except with a low-intensity brightness.

UPDATE 2: Fritzing didn't have a resembling matrix model, and I'm not doing this by hand now. I have wired (to my understanding) like in this schematic, with both the 5V and RSet coming from the MAX7219 onto the power line of the breadboard, RSet via a 10k resistor.

Here are two pictures of the current setup: 1, 2.
2 ground wires as per the MAX7219 Datasheet, DIG0-7 on columns, SEGDP-G on rows, RSet to 5V via 10k resistor and normal 5V.

I am obviously new to this and I don't mean to ask stupid questions so please be patient.

Are there any logical flaws in these pictures?

\$\endgroup\$
6
  • 4
    \$\begingroup\$ A schematic would be most appreciated \$\endgroup\$
    – Adam Head
    Commented Sep 29, 2014 at 13:15
  • 1
    \$\begingroup\$ Haven't made one yet, gimme a few. \$\endgroup\$
    – krystah
    Commented Sep 29, 2014 at 13:16
  • \$\begingroup\$ Downvoted because "gimme" isn't a proper word! \$\endgroup\$
    – Leon Heller
    Commented Sep 29, 2014 at 13:19
  • \$\begingroup\$ Added a link to the schematic I followed. \$\endgroup\$
    – krystah
    Commented Sep 29, 2014 at 13:32
  • \$\begingroup\$ What are you using to power everything? \$\endgroup\$
    – Grant
    Commented Sep 29, 2014 at 17:26

1 Answer 1

Reset to default
6
\$\begingroup\$

It sounds like a inadequacy of power to me based on the information you've provided. I believe this to be so due to a similar experience with a Dot-Matrix display. I was able to light only so many blue LEDs, until the power supply cut the power for overload protection. Upon upgrading to a 5 ampere power supply, I no longer experienced that issue.

\$\endgroup\$
3
  • \$\begingroup\$ This answer may well be correct based on the minimal information that was provided, so why the downvote? +1 from me. \$\endgroup\$
    – Tut
    Commented Sep 29, 2014 at 13:51
  • 2
    \$\begingroup\$ nice and succinct answer from a newbie, nice work. \$\endgroup\$
    – KyranF
    Commented Sep 29, 2014 at 14:51
  • \$\begingroup\$ Updated my question. If you got further insight it will be appreciated. \$\endgroup\$
    – krystah
    Commented Sep 29, 2014 at 15:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.