Midi toggle box

MIDIbox HUIs
1

Hi,

my plan is to build a midibox with 64 buttons and 64 leds (beside the encoder and buttons for menu),

the leds are under the buttons, (the buttons light when they pushed, toggle state)

i already tested this with my MBSEQ and works well

so my question is:

Since 64 leds have a max. current of 20 mA x 64 = 1280 mA the box would at least need a supply with 2A.

By supporting the leds with a led martix, a lot of power could be saved right?

Is there already a application where someone implemented a ledmatrix into a MB64 or MB64e design?

If not, what would be the best hardware setup to test and program this by my own.

I think the application for the led digits is a good way to start, but i am not quite sure.

thanks

chriss

2

Hi Chriss,

(this is not a programming specific answer, but I guess that you can excuse me, that I cannot dictate the code for all possible modifications due to time reasons…)

the assumption that each LED consumes 20 mA is wrong. One point is, that the max. current is limited by the 74HC595 (80 mA maximum), another point is, that the LEDs are not completely saturated due to the 220 Ohm resistor… in practice the current is mostly about 10mA

Best Regards, Thorsten.

3

hello thorsten,

thanks for your answer, good to hear that the SR can only deliver 80mA.

(this is not a programming specific answer, but I guess that you can excuse me, that I cannot dictate the code for all possible modifications due to time reasons…)

i can excuse this very easily, you gave so much code to us…

my hope was that there is already an existing project or code. but i will try on my own.

thanks again

chriss