MobiFlight Community Support

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A HUGE Thank You to everyone who participated in the forum, especially obviously to Pizman and Stephan who did an outstanding job over so many years providing an incredible service to the MobiFlight community.

The forum is still providing a lot of good content, hence we keep this information accessible.

Message #25063

Gabfus

Posts: 11

Hello I try to use max7219 display.
If I connect 5v and ground direct to max7219 the test button and chars displayed is OK. If I pass the 5v and gnd first on a breadboard and from breadboard on max7219 the test go KO.
Why ? the breadboard can be reduce 5v or introduce other problem?
I want use more max7219 and want put 5v/gnd on breadboard and from breadboard 5v and gnd on each max7219.

thanks

2022-01-29 15:14

Message #25073

pizman82

Moderator

From: ETSI, Germany

Posts: 6010

Supporter

Hi
The Max7219 are verry sensible.... A light touching can "kill" the System if the wires are not perfectly solder.
So a improvisonal Breadboard Logic is not recommend..... If you use wires then solder them on Max Side !

Your Problem.....
Maybe a "touching Problem" like explane above OR you missunderstand the basic Logic....
The MAX must be connected to the Mega ( including GRD and 5V) BEFORE the Mega get Powered.
If the connection get cut ( e.g. if you simply reset your wires on the Breadboard) then the Max will no longer work.
You need to RESTART the Mega again..... Simply cause the Max must be initialised !

Good Luck !

2022-01-29 16:51

Message #25094

kjoussen

From: Hamburg, Germany

Posts: 178

What also could cause this is that - as pizman said - the Maxes are really "bitches".

There must be two capacitors connected as well between +5V and GND: one polarized 220uF and one unpolarized 100nF.

It took me some days, too, to find out that this is mandatory.

2022-01-30 14:12

Message #25116

giocc

Posts: 21

Anyway, it is definitely better to avoid breadboards except for testing, and go for more stable connections like screw or spring terminals or solder joints.

2022-01-31 17:15