Official pin out/ports documentation

#21

One more thing. What do you use to link your breadboard and the Axoloti?

It is showed in this link:

Instagram Tom Whitwell on Instagram: “Trying out an #axoloti board. Bleeps.”

It is not a normal 40pin header, isn't it?

#22

Ah yes. It's a female pin header like this:

#23

Yes, the multimeter you show seems fine. You're mainly going to be using it as a ohm meter (to check conductivity and resistance values, and as a DC <5V voltmeter

#24

Thanks for this guys, I think I will also be placing an order in the new year.

has anyone tried any 'solderless headers', might not be as stable, but perhaps ok for beginners, concerned about soldering their axoloti board, until they get a bit of practice.
(I've so far only seen them on US sites, but perhaps can be found in europe?)

BTW @johannes perhaps this also could be an interesting area for the webshop.
have you seen http://www.sound-machines.it/index.php/shop-2/

they sell an NS1 experiment kit, which has a few components in, and some example circuits.
something like this for Axoloti could perhaps kickstart a few of us novice diyers into action,
and with a 'known' set of components, would mean the community could share different examples.

it kind of reminds me of the electronics kits I had as a kid... there might even be andinteresting market as axoloti as an education device for kids?!

#25

Connecting multiple Axoloti's together

I was wondering if there are any problems connecting 2 or more different axoloti boards together ?
For example I have a mono jack socket plugged into PC5 that I use with a switch pedal. I have the same thing on an other board. Can I use one as a trigger out (digital out) and the other as a trigger in, and just plug in a jack between the two, to send clock or trigger information from one to the other.
And on the same note, if I have a stereo jack socket on PA5 or PA4, (that I use with an expression pedal) can I use it to send analog out strait into an analog in of the same kind (with a stereo jack) ?
That way we could have a load of axoloti's communicating together without using midi

#26

Yeah, you could even do an analog modular-style patch bay with all the gpio's, with one or multiple axoloti core's. All gpio's are 3.3V, so that's ok if you only connect 3.3V sources.

I suggest a 220Ohm resistor in series between VDD and jack for expression pedal input, to avoid shorting VDD.

#27

Ok, so this is great news.
I just wanted a confirmation, so I sketched up using mono jack and stereo.
Can I just use mono jacks for analog out and in, or do I need to wire it up the stereo way ? (which works well with my expression pedal, thanks for telling me to add a resistor).

Capture switch.jpg1172x597 83.4 KB

The switch and pot was just for me for giving a maximum of modularity to the thing,
I suppose I could always have a 3 way switch and have all 3 configurations possible, one for expression pedals, light / distance sensors, (with a stereo jack), one for sustain pedals, triggers, digital out (led or other) and a pot or a button (in case you don't want to plug anything in)

#28

Looks fine. One extra trick could be using a jack with built-in switch(es), so the pot is connected when there is no jack inserted. Then you do not need an external switch.

#29

Sorry, I'm still trying to understand.
If I put 2 stereo jack plugs on 2 different axoloti boards, Then use a stereo jack to plug them together (for analog transmission) don't I have a problem with both VDD being connected together (with a 440ohm resistance between the two) ?

axoloti short.png635x666 57.5 KB

#30

Hello Paul,

I'm not sure if your drawing is referencing an older version of the board or not. I have a Axoloti Core V 1.0, and several of the pinouts are different from your wonderful drawing.

AXOLOTI PINOUT REDLINE.png1347x952 439 KB

I've attached a red-lined drawing that shows the pinouts that are different. If you have an illustrator/eps/pdf/svg file, I'd be happy to make modifications to the drawing, if you like.

Regardless, thank you for the the drawing, it really helped solidify the functionality in my mind.

Axoloti and X0X Heart
#31

thank you Dazzling Duke. You spotted a big error. I corrected the wrong pin outs and upload the original illustrator file to github for further modification.
Download: illustrator file

axoloti-gpio-io-v2.jpg842x595 271 KB

Axoloti and sensors
#32

Hello mtyas,
Finally did you wire that way, with a 220ohm resistance between VDD and jack? Did you use mono or stereo Jack for communication between Axolotis? And did you tried the jack with built-in switch? I guess it works since I saw your videos (exciting 3 Axolotis plugged together).
Thank you

#33

Yes to all questions. Stereo jacks, resistors on all jack sockets and I used jacks with built in switches.
It all works really well
I actually also put mono jacks (with switches) before some of my buttons, so that I can send or receive trigger signals. But I connected them to the GND and the Gpio's instead of VDD and Gpio (giving me more connection possibilities, like sticking a led onto a jack)

#34

Does anybody know if Doepfer modulation wheel kit can be plugged anywhere in the Gpio?

http://www.doepfer.de/zubeh_e.htm

And Yamaha BC2 breath controller?
http://usa.yamaha.com/products/music-production/accessories/breathcontrollers/bc2/
There is very few informations about specs in that previous link. Maybe more info here, page 8:
http://www.doepfer.de/pdf/WE_Manual.pdf
I read 5v and I think it should be 3,3v... Is there any risk of damage to the Axoloti in case of wrong potentiometer voltage?

Thank you very much

#35

The Doepfer mod wheel kit can be connected similar as the Potentiometer in the diagram top left here: https://sebiik.github.io/community.axoloti.com.backup/t/official-pin-out-ports-documentation/202/11
Not all gpios are suitable, only the one's capable of analog in.
Just use VDDA (3.3V) where Doepfer says to use 5V. Resistive dividers behave proportionally.
If you do not connect anything to the 5V solder pad, and do not involve an extra power supply, so only involving gnd, vdd, and gpio, it'd be hard to damage the gpio's.
I have heard evidence of the gpio's surviving exposure to 5V, but it is out of spec.

I have no experience with breath controllers, the situation is a bit different since there is active electronics inside, and seems to need a power supply of 12VDC.
here's some discussion:
http://www.eevblog.com/forum/projects/breath-controller-for-synths-w-bc-input-need-design-help/

#36

Thank you very much Johanes, first of all, for your incredible project, and for the time you spend helping us. Thank you for that information about Breath Controller. No I understand why it only works if supported by the gear. There are a lot of other interesting things to do with the Axoloti Gpio. I'll try to understand really how it works... it's a good thing is there isn't damage risk; it's an invitation to experiment.

And thank you Mtyas, I'll try the same double connections.

#37

Connecting the VDD's of two boards would not so much be an issue. The real issue is hotplugging the jacks if there would not be a resistor limiting the current. When you insert a jack, the tip of the jack (VDD) will connect to sleeve (GND) of the socket. I would not expect permanent failures caused by that, but it is going to reset the processor for sure...

#38

hello every one please excuse my newbie questions, I'm new to diy electronics however have been working with synthesis and music for over 12 years. I'm wanting to hook my axoloti up to a eurorack. I'm a little confused about what vdd is and what vda is. I know to amplify the signal to 0-5 volts I would want to use an op amp feeding back into the the inverting input with some resistors but that's about as far as I can figure. I would then run that output to the jack and also attach a ground. I've seen the diagrams for scaling cv down. Something similar to help amplify it would be useful.

#39

Ok I've been doing some research and this is what I've come up with where R(f) = 13.7K, R(g) = 26.7K also you would want to add a 100K across the input: a) so with nothing
plugged in you get zero out, and b) for some level of ESD protection. And i guess the ground from axoloti and eurorack need to be tied together.

#40

So, judging from the circuit, you want to convert 0-3.3V from the axoloti to 0-5V. I don't think 5V is the most obvious voltage to feed to eurorack, but it is a possibility (eurorack range is -12V to +12V, so anything in between that is a valid control voltage). For "digital" (trigger and gate) signals 5V is reasonable (will trigger most modules), but 12V is also fine (will trigger all modules), and even 3.3V should trigger many modules.

Anyway, some tips:
- The circuit you show is a non-inverting amplifier with a gain of (1 + Rf/Rg) = 1.5 (about)
- Probably no need to try to get exactly 5V out, why not use common resistor values.
- Putting 100k from Vin to ground indeed makes zero out when nothing is plugged in, but it doesn't provide any meaningful input protection. You could add a series resistor of 10k or so before just before the opamp input, depending on which opamp you use that may be good protection.