MobiFlight Community Support

I want to use Mobiflight to make the COMM1 and NAV1 radio's so I have 4 7-segments of 8 digits. I guess that each 7-segment display has its own CS-input, but that the Clock and Data-In signals are common for all the displays. Still Mobiflight forces me to assign CLK and DIN pins for each 7-segment display. That seems a waiste. Does anyone know if there is a way around this?
Regards,
Niek

Hi Niek,

that is so correct. At least if you connect each MAX chip (i.e. 8 digits) to MobiFlight individually. Then it goes without saying that you need the 3 connections for each MAX chip (plus 5V and GND).
However, if you build the MAX chips in a chain, you only need these 3 lines for the 1st chip. These lines are then passed on to the next board at the end of the board. The principle can be seen on page 13 of the data sheet (https://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf).
When building a chain with the small Chinese PCBs, there is something to consider. The 5V must not be looped through the boards, then nothing works from the 3rd display. The reason for this is the diode D1 on the circuit boards, which serves as reverse polarity protection.
These can either be unsoldered and replaced with a wire bridge, or each board is individually supplied with 5V. GND, however, can be looped through.
When building a chain with MobiFlight, make sure that the number of boards in the chain is specified when setting up the device (Menu -> Settings -> MobiFlight Module) to the right of DIN, CS and CLK, select the number in the Num field.
The boards must then be entered accordingly in the Config Wizard.

Hi Stephan,
Thanks! That was very helpful.
I see now that there is only one CS for the whole chain. Now it works.

All the best,
Niek

To avoid Confusion.....

I guess that each 7-segment display has its own CS-input, but that the Clock and Data-In signals are common for all the displays. Still Mobiflight forces me to assign CLK and DIN pins for each 7-segment display.

Take care if your setup is compatible with Mobiflight. !

With Single Chip usage ( No chain) Mobiflight need for each board all 3 single lines.... Means each Chip got its OWN CLK, CS, DIN
If you use a Chain then the Whole Chain got only 3 Lines from the Mega.... So here (whatever 1-8 chips are in use) all share also ONE CS.


Last week a user from Italia show us a special logic ( used for SimVim) .... Here its different.
This board technical not build a real chain.... Each Chip work as a single device....
BUT..... Those Boards share already DIN and LOAD..... Only CLK is single here.
(Sounds like your reported situation)

Means whatever its not chained, all Chips would recive the same signals..... but the CLK manage what display execute the data and what disply "ignore" the Data.
THIS is not compatible with Mobiflight.
If you got those Boards with PCB lines in that way you must rework the system (solder/desolder some stuff)!