MobiFlight Community Support

Hi all,

I know this is not a MF problem, however, I'm a little bit lost, so any help would be welcome.

So, I connected my Mobiflighted Arduino to a MAX7219, and that to 5 single 7segments (LTS4301E), wiring each MAX7219 SEGx pins to all the corresponding segments in the 7segments and each DIGx to the common cathode of the corresponding 7segment. Then I hit "Test" and nothing happened. I also tried running FS2020 (mapping Radio COM in the 7segment module), and again, nothing happened. I decided then to remake the connections one by one and check step by step. While doing so, I could never see anything when hitting Test on the Display Tab, but, when running FS2020 and trying to read the Radio-COM I observed the following:

With the five DIGx connected and just 1 segment in the first 7segment, it worked as expected
If I started adding segments in the same 7segment, when I tried to connect the third one, all of them went off
If I connected just one segment to the 5 7segments, it worked as expected

Could it be a power problem? An inestability in the MAX7219 (at the time I don't have capacitors to connect between Vcc and GND)?

Thank you in advance!

Sounds verry confusing.

First Idea.... Do you "initialise" the Chip ?

The Max7219 must be connected BEFORE you power the Mega. And the connection must be stay active at ALL time. If you just touch "improvisional" wires while the Mega is runnig all is killed and you must RESTART it.
Also it is not possible to change parts here while running. So always Disconnect the Mega.... And Reconnect it. Then start Mobiflight. And from that point not TOUCH the build.
( Note .... A Max is a nice Chip.... But it finay need SOLDER Contacts.... Else it will crash 1000 times per Day )

2. Correct Displays ??? Maybe this sound like a Common Anode Problem ! Ony Common CATHODE Displays will work with a Max7219. Please Confitrm that !