Addon Board for extra input / output?

#1

Are there any addon boards that could be used with the Axo to create more inputs / outputs, something like the "Teensy Audio Adapter" or anything else that might be out there ?

#2

Not yet. But maybe somebody will build something if they have the need for it.

#3

The Euxoloti Eurorack adapter @paul is designing already has 8x extra gate/trigger outputs, and he also designed a 2x CV output, so it's definitely possible.

a|x

#4

@Gavin
my gat8 pcb uses a 74hc595 and runs by +12V power supply. It can be chained with more gat8 pcbs…at the same time you can also use 74hc165 to read more inputs. but you will need some tristate puffer on the MISO line between 165 MISO and axo MISO which is active while CS for 165 is enabled. If your input signal is > AXO VCC or < AXO GND you need to protect the inputs. this can be done by simple transistor buffer or resistor + 2 shotky diodes which clips the signal to axo min/max voltages.

For DAC: if you are able to solder fine pitch smd, you can use a dac8552 IC with axoloti. example patch is at github.
You can easily use this dac or a mcp4x22 and a mcp6004 op amp as output buffer on a strip board.

Or the easiest way is to have a look at the ucapps project. their DIN and DOUT pcbs works perfectly with axoloti. I got stocked by the AINSER64 module. Maybe you or some other can get it working.

#5

Thanks but that's a bit over my head. I've done some work with Arduino's, sensors and addon boards etc, but thats about it, I just thought with all the options of addon boards out there it may help to extend the capabailities of the Axo without to much tech involved.

#6

it's not that complicated as it seems to be…must different between arduino shields and axo is supply voltage. most arduinos works with 5V signal level and axoloti max. voltage is 3,3V.

the teensy audio board should also work with axoloti (teensy signal level is 3,3V = Axoloti) but you have to convert teensy library to axoloti…

here are some examples for I/Os and axoloti which you can easily edit to use them with ucapps DIN, DOUT & AIN pcbs:
74HC595 shift register (expand on/off outputs)

4051 analog De-/Multiplex (expand analog or digital in- or outputs by 3 wires + signal)

MCP3208 8x 12Bit ADC (expand analog inputs. inputs are protected by internal clipping diodes.)

MCP4922 2x 12Bit DAC (outputs two single voltages between GND and VDD)

and a lot of informations about input protection level shifting etc. is described at the Official pinout thread.

#7

Apologies all,
I think I did not communicate my details correctly, I mean more AUDIO Input / outputs.
I have no issues with the Analog and digital I/O's.

#8

to be honest, i am on the quest myself of having 6 (or more) audio outputs (24bits, 96khz)

why you might wonder: to put it simple: surround sound! i want to learn how an dolby surround matrix exactly works.

the DAC8552 ic looks promision, but 'only' 16bits, plus the breakout boards that convert to dip cost 25$ / piece?? (the ic itself is like 8-10$)

if anyone can hand me 3 breakouts for like 40$ soldered, let me know! i'd happily take them as i can't solder components that small ^^;

#9

Sorry, I don't have the time to actively support questions about expanding the number of audio input and output channels.
It is technically possible, but doing so requires familiarity with firmware development, finding your way through the STM32F4 datasheets (a couple 1000 pages), and I'd also recommend having an oscilloscope on the workbench, and a substantial investment in time.
While suitable for control voltages, I'd recommend against DAC8552 for audio, use a convertor made for audio applications.