Setting up Bela for PureData

david

Thank you. Useful explanation. I have my system working but I need to use the loudspeaker output and I am having some issues with booting up.

<WORKS AS APPROPRIATE> If I connect the USB, air for Bela to boot and then connect an external PSU set to 5V to the black external power in the loudspeaker works fine along with the rest of the system.

<DOES NOT WORK AS APPROPRIATE> If I remove all power from the Bela board it works partially - the control switches do not work at all, the audio output is at a different level (I hear it when it should be quiet but it does respond to the frequency control as it should).

Is there something I need to know about booting Bela without the USB - I was thinking it would be like an Arduino (boots up to last loaded patch with power on from an external source?

giuliomoro

david (boots up to last loaded patch with power on from an external source?

You need to set the patch to run on boot , see the instructions here. If you already set the patch to run on boot, but have changed some of the options in the IDE, you have to set it to run on boot again for the new settings to be applied when running on boot.

david <DOES NOT WORK AS APPROPRIATE> If I remove all power from the Bela board it works partially - the control switches do not work at all, the audio output is at a different level (I hear it when it should be quiet but it does respond to the frequency control as it should).

I am wondering if there is a ground connection that is missing when you disconnect your computer? You could test it two ways:

connect the USB, connect an external PSU, make sure it works. Then, while it is running, disconnect the USB. What happens then?
start it with power from the barrel jack, get to the "does not work as appropriate" state. Then plug the USB into your laptop and try again immediately: does it work?

david

IGNORE MY LAST ENTRY - let me rewrite the text above - something has gone wrong...

I have my system working but I need to use the loudspeaker output and I am having some issues with booting up when an external extra PSU is used as follows:

<IT WORKS AS EXPECTED> If I connect the USB, wait for Bela to boot and then connect an external PSU set to 5V to the black external power in the loudspeaker outputworks fine along with the rest of the system. All is good.

<DOES NOT WORK AS EXPECTED> If I remove all power from the Bela board and then connect ONLY the eame external PSU set to 5V as above, the system works only partially - the control switches for changing sound parameters do not work at all, the audio output is at a different level (I hear it when it should be below a preset threshold) but it does respond to one sloder [the frequency control] as it should.

Is there something I need to know about booting Bela with the external PSU on the black connect only (assuming this can be done) WITHOUT the USB - {I was thinking it would be like an Arduino (boots up to last loaded patch with power on from an external source}?

David

david

Thanks. The run on Boot which I thought was set was not set to the folder my program was in. Sorted that and now it is working as expected on either the USB poere OR starting up from the barrel jack power. Thank you once again .... David

giuliomoro

Great!

In case this behaviour is confusing , the rationale behind it is that - unlike on Arduino - you have several projects on the board at any one time and you may not necessarily always want the latest one you edited to be the one you play on boot. For instance, you may want to keep a "known working" version to run on boot while you work on the next revision in a different project. Once the new version is ready, you'd switch over to that for running on boot.

david

Yes I get that - thanks. A lot to take in but things are working. A minor thing - in usign the loudspeaker connector (which is working fine) the connector I have that looks like it should fit is not really exactly the right shape and is bending the bela speaker pins. What is the spec for the connector?

giuliomoro

see here

david

Thanks. Could I ask a Q - I want to try MIDI with Pure Data but I have been looking around to see what interface and then what lead and then I finally realised that I do not know which USB connector on Bela to get a lead for. Is it the Micro connector used to link to the computer or one of the sockets on the other end of the board?

giuliomoro

You can just plug a MIDI controller in the USB-A port that is on the board. This should show up as hw:1,0,0on Bela.
Additionally, Bela shows up as a MIDI interface on you computer (through the USB cable you normally use to connect to it), so you could also send MIDI from/to your computer. This interface is hw:0,0,0 on Bela.

You can get a list of all connected MIDI devices by running amidi -l in the console at the bottom of the Bela IDE. The interface hw:1,0,0 is the one that Pd on Bela automatically attaches to, but you can also tell it to connect tohw:0,0,0, or any other one, by following the instructions in the PD hello-midi example, i.e.: by adding the following to the patch:

[loadbang]
|
[hw 0 0 0(
|
[s bela_setMidi]

david

Thanks - what I am 'stuck' with is which is the USB-a port? Is it the one I connect to the computer to program Bela with or is it at the other end? This also determines what connector a MIDI interface will need (I do not have one - do you have a recommendation?).

giuliomoro

david which is the USB-a port?

USB-A is the OTHER one (that is the one you are not connected to already, which is called a "USB Micro-B"). So any USB MIDI interface should do really ...

david do you have a recommendation?

I am no big expert here ... what type of device are you looking for?

giuliomoro

giuliomoro USB-A is the OTHER one (that is the one you are not connected to already, which is called a "USB Micro-B"). So any USB MIDI interface should do really ...

sorry that's "mini-B" on a Bela ("micro-B" is on BelaMini).

The USB port on Bela that you normally connect to your computer with the provided cable is "USB mini-B". The one that is under the audio connectors is a "USB-A" and that is where the MIDI device will go.

david As a MIDI interface I want to use MIDI in to control sounds from Pd.

Ok, would that be just knobs, buttons and sliders, or something more keyboard-like?

david

Thanks - I assume then that 'USB Micro-B' is the big USB or the small one ('micro' I assume relates to the small one) but I may be wrong and that these are the sockets under the loudspeaker end of the board? I cannot find a Bela diagram that refers to these two sockets. As a MIDI interface I want to use MIDI in to control sounds from Pd.

david

Thanks. I want to use a keyboard (as an organist!) to play my Vocal Tract Organ in multi parts. I have completed a version that is played with a pitch slider for a group to perform with - I plan to use it with the alaryngeal choir (look at 'ShoutAtCancer' website if interested in them) who 'sing' using belching speech. This way they can harmonise. I have an Arduino version but the audio quality is not very good and I cannot control the spectrum as well as I can in Pd. Next this is powering the Bela as a portable device - I note you have used LiPo3.7V batteries which I plan to try - if you have any advice or charging circuit thoughts I would be grateful!

giuliomoro

david . I want to use a keyboard (as an organist!) to play my Vocal Tract Organ in multi parts.

mostly any keyboard MIDI controller available on the market will do, really. It's your choice of key size, number of keys, weighted/half-weighted/non-weighted ...

david - I note you have used LiPo3.7V batteries which I plan to try - if you have any advice or charging circuit thoughts I would be grateful!

The easiest option is probably to charge it with a USB battery such as the ones for mobile phones. Using a LiPo is fairly easy on BelaMini (see here), but it gets a bit more cumbersome on Bela, as it requires accessing some of the SMD soldering pads on the BeagleBone, if I remember correctly. One disadvantage of using a 3.7V LiPo is that the analog inputs and outputs stop working, and you are left with only audio and digital I/O.

lokki

david to play my Vocal Tract Organ

can you elaborate a little on this? is this a custom instrument or something existing. you write about an arduino implementation, do you have a link for that? or a PD patch? very intersted in this.

david

The Vocal Tract Organ is something I have been working on to drive 3-D printed vocal tracts - it was used for this paper https://www.nature.com/articles/s41598-019-56316-y and I do have other papers but they are not on-line. Happy to email them. So the version here is Pd based as I work on it and I do have an Arduino version. Both need additional hardware.

lokki

very nice. this sounds amazing. i am very much into synthetic vocal emulation, so might give this a go. i have no 3d printer at hand, but might be able to rent a place... would be nice to read those papers

for a midi controller maybe a qunexus would be good for you? it enables you to modulate two parameters while playing a key, by pressure and position, and still is quite cheap.

my email: simoniten(at)swissonline.ch

(at) = @

david

Hi again (after a long break!). I want to control the gain via adc~ and cannot get it to work (I am confused by the channel numbering which is part of the issue).

So I decided to take it a step at a time so wrote the following patch to check I understood which
alt text
channel of output I was working on. The signal can be heard on channels
DAC 0, 1, 2, 3, 4, 5, 6, 7 AND on
ADC 1, 2, 3, 4

Surely it should just be audible on DAC~ 1 for this patch or am I really missing something?

giuliomoro

david The signal can be heard on channels
DAC 0, 1, 2, 3, 4, 5, 6, 7 AND on
ADC 1, 2, 3, 4

what does it mean that the signal is heard on channels "ADC 1,2,3,4"? Are you listening to an input?

What board are you on? [dac~ 1] should give signal only on the first audio output (out 0 for CTAG, out LEFT for Bela or BelaMini).

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