MCU input protection and multiplexing

Breakout board for MCU input protection and multiplexing.

Scales Eurorack level to safe 0 – 3.3 Volts, these scaled signals can be used directly or via the multiplexer thats on board.

I have designed these while working on DSP audio for the electrosmith daisy, but you can use it with any other 3.3 V MCU.

C++ abstraction to use with unipolar LFOs and daisy   

I use a lot of Arduino based unipolar LFOs. In order to get full parameter range with these unipolar LfOs, but also be able to use bipolar LFOs i use this abstraction.

// center 1.64 volt from mcp6004 input protection + Dead zone to prevent tiny floating

inline float bipolar_center_mod(uint16_t adc_val, uint16_t center = 32768)

{

int deviation = abs((int)adc_val – (int)center);

if(deviation < 100) // ~1% deadzone = 100

return 0.0f;

return daisysp::fclamp((float)deviation / (float)center, 0.0f, 1.0f);

}

Max Gen abstraction to use with unipolar LFOs

In max gen this abstraction should do the trick, with or without deadzone for the daisy seed.

I have put up a small website with more pictures, links and code.

Also there you can find a DCDC converter and input output opamp board for the daisy seed.

These 2 breakout boards helped me tremendously while developing DSP audio on the Daisy Seed and interfacing with eurorack. 

The daisy seed breakout boards are an open source project.
The schematics and PCB designs are licenced as CC BY-NC-SA 3.0.

For the daisy seed power management and op amps i refered to:
kxmx blümchen and daisy patch by electrosmith

For input protection:
kxmx blümchen and Mutable instruments clouds

For multiplexing:
Takumi Ogata electrosmith tutorial