Diodes for row buttons on led matrix?

MIDIbox FM
1

On the DIN schem the 4 row buttons for the led matrix are going into just one d-input/header. I understand that it is to save from adding a whole extra DINX module but I see there is a part number for diodes on the schem aswell. I can’t say I have done proper testing of how this works and I don’t have a breadboard tester. Can someone throw me in the right direction for some typical construction?

I also have a question about the DOUT module schem with 4 rows of leds anodes connecting to 4  d-inputs/headers which are also occupied by the DIN’s wiring aswell. Does the DIN get wired directly to the DOUT and the buttons connected to the DOUT? And do the leds get connected to the same inputs as the row buttons do?

I am not sure if I am understanding the correct way to do this.

Regards,

echo

2

Those Diodes pull down the respective matrix row for the key which is pressed.

Those are standard 1N4148 silicon diodes, which you can find almost everywhere and literally cost nothing :).

The wiring pictured is correct.

3

Thanks for confirm that for me lucem. I will probably be back with more questions when my box and 24 leds are sitting in front of me.