Post by thetechnobear on Aug 17, 2018 15:54:40 GMT
So before I started on the BelaMini module, I actually had started on a different project for connecting to AE modular, connecting Axoloti!
this is not finished but as I had the oscilloscope out to test power noise on the BelaMini ( see this post for those results) , I thought Id test the Axoloti, to see if its also had noise.
heres that in progress:
but while Im at it I thought Id discuss this project a bit and what it is, and what it entails.
What is Axoloti?
Axoloti is great, actually one of my favourite projects... its a DSP board, design by Johannes Taelman, (Axoloti.com) which was released a couple years ago.
its a full audio board, that you design patches using a visual patching editor on your PC/Mac, which you then upload and it can run completely standalone,
its very high quality, and cheap (65 euro!) , with very low latency, and because its all based on the SMT32F4 micro controller, no OS, so it starts immediately (ok, sub second for patch to load)
its got stereo in, out and midi in/out and also usb for midi in/out... and a whole load of GPIO.
for 65 euro, i think its unbeatable really.
Why integrate it with AEM?
why not
nah seriously its great for digital synthesis and FX, and super quick to patch, so I thought it would be an excellent side-kick... I mainly thought for FX.
Its a great thing to use with AEM, even without the modifications that Im discussing here, you can simply use the audio in/out (which are DC coupled) .
What does integrate it mean?
so the basic idea, is I want to directly power Axoloti from AEM, and also I want to be able to control it via AEM CV for modulation possibilities (and send it audio of course)
How am i doing it?
here are the 2 boards I created a while back (and was re-testing today)
so, the axoloti board is a bit too big to fit into the AE case, so at least for now I decided against this(ok, it could fit horizontally, but then it take about 5U)
instead what I thought Id do is have it as a external module, that would some how plug into the AEM easily (my thought is using a ribbon cable, like the RackLink)
so the two boards Ive made so far are:
board 1 - 8 cv in from AEM to axoloti analog inputs (aka 5v to 3.3v)
board 2 - 2 audio in from AEM to axoloti DC audio input (5v, 2.5 centre) , 2 analog cv output to AEM cv out (3.3v to 5v)
(you can see i did this before BelaMini, but the size of the boards... these strip boards make the circuit even bigger )
boards, and axoloti are powered (as you can see in picture) directly from the AEM.
you'll notice the 'odd one out', is no audio from axoloti back to AEM... mainly because i thought id use it initially as an fx box, but I might add audio output later perhaps.
even with this, this still leaves me with 5 more analog inputs on the axoloti for potentiometers, and a bunch of digital in/out. (switches / leds)
board 1 and 2, are just voltage level converters really, using op-amps to scale the voltage, with a biasing function (to make them suitable for audio too, with no/little dc offset), any small calibrations i need to do, can be done in software on the Axoloti. (eg due to resistors not being quite right value)
Where have I got to, whats left to do?
That is why I got it all out today, to find out , what I needed to do to finish this off
The boards are done and tested on the bench, using my AD, and the Axoloti powers properly off the AEM.
I also did the power test today, to see if it suffers from the same issue as BelaMini, and it appears not too... so thats a promising sign, and mean I can 'crack on'.
so I need to:
a) Decide how Im connecting the boards to the Axoloti,
I was going to use patchwires, but this feels a bit frail (probably need to create a connector)
b) Decide on Enclosure, and mount additional potentiometers, switches, leds
I do have an enclosure, but I think its a bit big for my needs
also some of this can be done later, more important to get basics working so I can test it.
c) Decide how to connect the 'box' to AEM.
Ive got a 10pin ribbon (like AEM), and also sockets to make an AEM module, and a connector on the Axoloti box...
but if I use the AEM ribbon layout, thats only 6 data pins
and even if i use my own thats still only 8 data pins (since i need to carry ground and 5v as well)
Ive got 12 data , or 14 if I add audio output later, which makes sense ... plus 2 more for voltage, thats 16.
so i probably need to get a bigger ribbon (20?) and connectors.
though, Im quite tempted to perhaps initially start with the 10pin for testing....
this is where i got to last time, and hence why I stopped...
decisions, decisions
anyway, hope it was interesting to some,
and I'll be back to update once its all working
this is not finished but as I had the oscilloscope out to test power noise on the BelaMini ( see this post for those results) , I thought Id test the Axoloti, to see if its also had noise.
heres that in progress:
but while Im at it I thought Id discuss this project a bit and what it is, and what it entails.
What is Axoloti?
Axoloti is great, actually one of my favourite projects... its a DSP board, design by Johannes Taelman, (Axoloti.com) which was released a couple years ago.
its a full audio board, that you design patches using a visual patching editor on your PC/Mac, which you then upload and it can run completely standalone,
its very high quality, and cheap (65 euro!) , with very low latency, and because its all based on the SMT32F4 micro controller, no OS, so it starts immediately (ok, sub second for patch to load)
its got stereo in, out and midi in/out and also usb for midi in/out... and a whole load of GPIO.
for 65 euro, i think its unbeatable really.
Why integrate it with AEM?
why not
nah seriously its great for digital synthesis and FX, and super quick to patch, so I thought it would be an excellent side-kick... I mainly thought for FX.
Its a great thing to use with AEM, even without the modifications that Im discussing here, you can simply use the audio in/out (which are DC coupled) .
What does integrate it mean?
so the basic idea, is I want to directly power Axoloti from AEM, and also I want to be able to control it via AEM CV for modulation possibilities (and send it audio of course)
How am i doing it?
here are the 2 boards I created a while back (and was re-testing today)
so, the axoloti board is a bit too big to fit into the AE case, so at least for now I decided against this(ok, it could fit horizontally, but then it take about 5U)
instead what I thought Id do is have it as a external module, that would some how plug into the AEM easily (my thought is using a ribbon cable, like the RackLink)
so the two boards Ive made so far are:
board 1 - 8 cv in from AEM to axoloti analog inputs (aka 5v to 3.3v)
board 2 - 2 audio in from AEM to axoloti DC audio input (5v, 2.5 centre) , 2 analog cv output to AEM cv out (3.3v to 5v)
(you can see i did this before BelaMini, but the size of the boards... these strip boards make the circuit even bigger
)boards, and axoloti are powered (as you can see in picture) directly from the AEM.
you'll notice the 'odd one out', is no audio from axoloti back to AEM... mainly because i thought id use it initially as an fx box, but I might add audio output later perhaps.
even with this, this still leaves me with 5 more analog inputs on the axoloti for potentiometers, and a bunch of digital in/out. (switches / leds)
board 1 and 2, are just voltage level converters really, using op-amps to scale the voltage, with a biasing function (to make them suitable for audio too, with no/little dc offset), any small calibrations i need to do, can be done in software on the Axoloti. (eg due to resistors not being quite right value)
Where have I got to, whats left to do?
That is why I got it all out today, to find out , what I needed to do to finish this off
The boards are done and tested on the bench, using my AD, and the Axoloti powers properly off the AEM.
I also did the power test today, to see if it suffers from the same issue as BelaMini, and it appears not too... so thats a promising sign, and mean I can 'crack on'.
so I need to:
a) Decide how Im connecting the boards to the Axoloti,
I was going to use patchwires, but this feels a bit frail (probably need to create a connector)
b) Decide on Enclosure, and mount additional potentiometers, switches, leds
I do have an enclosure, but I think its a bit big for my needs
also some of this can be done later, more important to get basics working so I can test it.
c) Decide how to connect the 'box' to AEM.
Ive got a 10pin ribbon (like AEM), and also sockets to make an AEM module, and a connector on the Axoloti box...
but if I use the AEM ribbon layout, thats only 6 data pins
and even if i use my own thats still only 8 data pins (since i need to carry ground and 5v as well) Ive got 12 data , or 14 if I add audio output later, which makes sense ... plus 2 more for voltage, thats 16.
so i probably need to get a bigger ribbon (20?) and connectors.
though, Im quite tempted to perhaps initially start with the 10pin for testing....
this is where i got to last time, and hence why I stopped...
decisions, decisions
anyway, hope it was interesting to some,
and I'll be back to update once its all working