MobiFlight Community Support

Hello everyone,
I am building a reduced overhead 737 with mega arduino boards and I have to order the pcbs with leds to build the annunciators.
Since the company already manufactures them with leds and resistance included, do you know if this can create problems on the functioning?
I am a beginner in electronics.
Best regards

Yes this can occure in problems !
Two possible issue Spots !
Important is the logic behind.

1: Mobiflight work with a One Pin = One Device Logic...... So every LED is located to it´s own Pin !

Basicly there exist 2 Systems here..... Some manifactur work same way..... Means the LED are on the PCB..... And finaly there is a big Connector ( Mostly for Flat wires) that have a line for each LED.... So you just set a Flatwire Connector to this port and you got many many single Output Lines that can be connected to a MEGA.
The other System is a Matrix or Multiplexer Logic.... Means there is a Chip/Controller on the PCB and all LED Lines go to it..... Finaly there is a IO Interface on that controller that must be wired to the Controller ( like a Mega) .
Here we would send just a adress like " Please Change status of LED that is adressed "00001000" or so. Thats NOT possible with MF. We not support Multiplexer or Matrix Systems.

So.... Get sure the PCB work with a "Single Wire for each LED" System. Else MF is not compatible.
You can see this on the Shematic of the PCB (datasheet) or by ask the manifactur !

****

2: Mobiflight work with a Common Cathode System for the LED.
Means all Cathodes from LEDs are lined to a GRD Pin on the Mega...... The Anodes are lined specific to the single Pins you like to use for controlling the LED.
If Function is ON the Pin on Mega support 5V to the LED..... If Function is OFF it is Ground.... so no power is send to LED.

Some PCB Manifacturs ( Like Hispapanels) work with Common Anode..... Means inverted.
In case LED´s work only in one direction we not can simply swap the 5V and GRD wire.
Here exist a workarounds
If the PCB is still finished we must change the value of all Output Configs reversed.... Means MF send OFF if it should be ON or send ON if it should be OFF.


So.... Check if LED System is Common Cathode to have no problems..... If Anode then calculate with some more work to build it. But it should be possible in both situations !

Thank you very much

https://oshwlab.com/jkatz098/737-annun