LoopA V2 Introduction, Features & Support Thread

[jplebre]

Hi Folks, thank you so much for clarifying things for me.
@latigid on Thank you for the replies. My workflow usually is using a step sequencer for either some melody/drone/rhythmic jam, but once I settle on something I switch to my musician's brain and perform on top of it the rest of arrangements and orchestrations. For the idea, I want to develop I definitely need some step sequencer of sorts to develop one or more layers of ostinatos, because of the "feel" those sequencers have especially when you start playing with polyrhythms. 
I don't mind getting a separate step sequencer and when things are settled record the sequencer midi out into the LoopA before overdubbing. 
So, is there no song mode at all? I mistakenly thought a session could so something of the sorts :)

 

@Hawkeye Heya, thank you so much! Is there any sneak peek info/forum thread/videos on that codename matrix? I've read a few references to it here on the forum but couldn't find anything specific :)
 

So, I think a couple of questions are in order :)
- Is the song mode a potential addition on a later firmware?? :)
- Can the scenes/tracks be accessible by external MIDI control (ie. an external sequencer takes over the "song structure" duties).

- I've been looking around for the SEQv4+ manual but couldn't find one (Thank you for LoopA's one, very useful)

[Altitude]

10 hours ago, Hawkeye said:

 

Another idea - are you by chance using a Mac? With their newest O.S. i think the USB ports are not renamed after flashing a firmware via MIOS Studio - that would mean you'd already have the LoopA software on, but the USB port is still listed as MIOS bootloader - if that's the case, there is a way to reset the USB cache, quoting TK.:

"So far we only noticed a minor issue when an app changes the number of USB MIDI ports or the device name. Such changes won't be taken over automatically, instead you've to delete the old interface description in the Audio-MIDI-Setup:

• start the Audio-MIDI-Setup of MacOS (e.g. search for "audio-midi" with Spotlight)
• disconnect the core module from USB
• delete the interface in the Audio-MIDI-Setup
• connect the core module to USB again"

If that also was not the cause, i think there should be the option to directly connect a mini-USB Cable to the waveshare daughterboard on top of the LoopA core - then i think the Waveshare Core power selection switch needs to be set to USB - this should then allow MIOS Studio to upload the hex directly. If that worked, there might be a connectivity problem between Waveshare core and the LoopA core USB port.

If uploading via the mini USB port also fails, we'd kindly ask for pictures of the front and backside of the core PCB to have a closer look :)

Best regards!
Peter

> could you check if you're using the newest MIOS Studio 2.4.9?

Check.

>Another idea - are you by chance using a Mac

no

>connect a mini-USB Cable to the waveshare daughterboard

Ok, here's where it gets weird.  That DOES work.  The app will boot and I will get the Loopa ports now.  So that means that the main USB seems to be working but there is something hanging up the core preventing it from starting correctly.  

 

[latigid on]

Check the 22R resistors R30/31, TVS diode. Check the USB pins PA11  PA12 make it to those resistors and the MCU chip (2x2x25 pinheader soldering). Check for shorts to 0V. Check PA10 (USB ID) is floating and no jumper is in J20. Check the USB socket.

You might also try reflashing the bootloader with hold mode (JPA0, needs at least R102 mounted) or even via JTAG if it got corrupted somehow.

[Altitude]

Tried all those already including reflashing the bootloader.

I'll go over the core header again

[lp1977]

Hi, @Hawkeye and @latigid on,

I just finished building the LoopA and I must say that I find the kit to be every bit as nice and solid as the V4+ kit.  Fit and finish is top notch.

 

I do have a few questions/suggestions about things I have run into:

 

1) After creating a new blank Session, when saving for the first time you have to manually select an unused Session slot, otherwise you will overwrite the last Session you loaded with the Load function. This has happened to me a few times already from muscle memory since, once you’ve already saved the Session at least once and get into the flow of saving minor changes and additions, it’s easy to just hit Menu + Disk —> Save quickly each time to save your changes. 

 

Question: Is there a way to have the initial save of a new Session default to the first unused Session slot? Not a dealbreaker by any means, but might help with workflow.

 

 

2) When recording MIDI note input from an external MIDI keyboard, if I hold a note for the entire loop length, I have to let go of the note a little before it reaches the beginning of itself. If I miss the mark early, the note will end too early and I’ll have a gap that I have to manually lengthen, or if I miss it late, the Note Off will kill the entire length of the note and I’ll wind up with a very short note. 

 

Question: Is there a way to have the note snap to the beginning of itself or have the end of the note automatically end and join the beginning of itself for a seamless drone type note? Even overlapping would be fine, but I’m not sure how that could work with the Note Off being sent. Again, not a dealbreaker but would help reduce the time needed to manually fix the note. Maybe I’m just not approaching it in the right way. 

 

 

3) I have been using the LoopA as master clock and have been syncing drum machines and my Keystep (sequencer/arpeggiator). When the LoopA is stopped, the clock is also stopped and my synced machines are waiting for clock before they can be used on their own, for trying out ideas or working out parts soloed. 

 

Question: Is there a way to add, maybe in the Setup page, the ability to toggle a constant clock for each of the MIDI Out ports? Then only the start and stop commands would need to be sent with the Run/Stop button. With it being a toggle, you could turn this feature on and off per output port, depending on the type of MIDI device you have connected and what it likes to see. 

 

These are just suggestions of course.  All in all, I find the LoopA to be a very fun piece of gear that I enjoyed building and look forward to using for a long time.

[Hawkeye]

@Altitude yes, with that problem description ("flashable by mini USB"), i'd also think it could be the core headers or anything in the connectivity path from the MCU to the LoopA core USB port - e.g. the TVS protection diode is relatively small and might fit in in a few orientations :).

@jplebreno problem, to answer a few questions:

* a "step recording mode" should be possible, i.e. the LoopA could record in this mode on an "armed" clip, if the sequencer engine is not running and could proceed the sequence position by configurable time-increments/intervals, e.g. by quarter notes - this would then be very much like SEQ based step recording.
* scene-switching or muting/unmuting of tracks would also be easy targets for remote MIDI control, would implement it, when more people request it
* yes, in the future, a song mode is planned, you can even see its prepared menu icon on github :)
https://github.com/midibox/mios32/blob/master/apps/sequencers/LoopA/gfx/LoopAIconFont.png
In a LoopA session, you have scenes, which already allow a kind-of song arrangement - but for now, you'd still manually need to cycle through scenes with the upper-left encoder.

Regarding the MatriX - there's no official teaser out yet, we've been working on it since a while now and we hope to be able to reveal something at some point in time, but we won't give a certain date (lesson learned with the v4+/LoopA) :) - you can google a few youtube demos about the BLM 16x16+X - the MatriX will be its successor with improved hardware and also with support to attach it to the LoopA as well - there are two BLM ports, so you can have one MatriX connected to a LoopA and a SEQ v4+.

Finally as a good SEQ v4+ manual, i'd recommend to use the v4 beginner's guide - it's very well written and shows the capabilities - the v4+ is just like the v4 with an additional selection bar - what is selected is determined by the circular arranged buttons around the jogwheel - you could select tracks, layers, mutes, ... here's the recommended handbook: http://wiki.midibox.org/doku.php?id=mididocs:seq:beginners_guide:start

Best regards,
Peter

[Hawkeye]

@lp1977 Thanks a lot for your feedback! Glad you liked the build process and enjoy the LoopA itself! :). @AdrianH truly did a phenomenal job with the case, i really like it, too! :)

I've added your requests to the LoopA dev wishlist - currently time is a bit limited and we also have to make also sure not to "overload" the user interface of the LoopA - it should always be a device that is easy to use, also for new users not knowing the endless feature list of the SEQ v4+ :) - But any kind of workflow improvement is very welcome and two of your requests fit into this category! :)

#1 "Auto session increment after initialize" - The idea with the "auto session increment" when a new session was created is a really good idea, as it prevents accidental overwriting, added to the list, thanks! :)

#2 "Automatic note length snap" - this would be a nice setup feature, it would not take up any UI space on any screen and the feature itself also makes a lot of sense and is easy to understand - a very welcome addition! Parameters to the setup option could be "disabled" (default) /  "next clip note" (which matches your request, if there is only a single note, it will "prolong" the length until it reaches its own note start position, but if there are already other prerecorded notes, e.g. when overdubbing, this would allow to "fill the blanks" - maybe good for a mono synth to avoid unwanted "303" style slides/portamentos) / "onto beat" (prolong length until the next beat is reached) / "onto measure" (prolong length until next measure is reached) - thanks for the idea, added as well! :)

#3 "Independent MIDI clock on output ports" - that's unfortunately not easy to realize - for the LoopA, the sequencer engine is either running or not, there's no easy way to have a running "sub sequencer" on any OUT port - as it is also a quite advanced feature, this might be confusing for new users - i think it would probably be better handled by a dedicated add-on device (e.g. a MIDIbox :)). But there should be an (i think) easy way to handle this workflow: as long as your LoopA tracks are muted, you can easily drive (configurable) MIDI clock to any output ports - i do this with the Machinedrum. So you'd let the sequencer of the LoopA run and drive your drum machines and other sequencers and then just "add" LoopA melody tracks by unmuting them or launch them all at once by switching to a new scene - wouldn't that work?

Can't promise anything on the timeframe right now, but #1 & #2 should be present in a future firmware - thanks again for the suggestions!
Have a good evening!
Many greets,
Peter

[jplebre]

@Hawkeye thank you so much for your time!

If the song mode is indeed planned and on its way, targeting scene switching/mute unmuting from MIDI should be less of a request (my main use case would be to sequence/trigger it externally.
Thanks for the links for the SEQv4 beginner guide and the BLM matrix, I'm going to dive a bit more into everything in this forum about these 2 projects and wrap my head around all this!

Cheers!

J

[Altitude]

Im not sure where to go from here.  

1. Power good.  5V and 3.3V where marked
2. rehit all joints on the header, no change
3. Orientation of TVS is correct
4. 22R resistors are fine
5. Tried various USB cables/multiple computers

 

Other observations: 

• the app started once.  This was with the mini USB direct to the core, i could not repeat this behavior
• I can no longer get the miniUSB to do anything, it will start the device since the power led will fade in and out but no USB devices show up
• nothing is coming out of the midi ports
• with the main USB connected, I get the upload request over USB and feed back when I send the hex but I cannot send any other console commands to the bootloader (i.e."help" does nothing)

Does your core = the STM discovery core? As in does it take the same bootloader?

Edited June 23, 2020 by Altitude

[latigid on]

1 hour ago, Altitude said:

Im not sure where to go from here.  

Post some pics of the PCB to let another set of eyes go over it for something obvious?

 

1 hour ago, Altitude said:

1. Power good.  5V and 3.3V where marked
2. rehit all joints on the header, no change
3. Orientation of TVS is correct
4. 22R resistors are fine
5. Tried various USB cables/multiple computers

There's not a lot to the USB but I would check/scope the line between the 22Rs and PA11-R30/PA12-R31. Do the header pins contact the MCU chip pins?

 

1 hour ago, Altitude said:

Other observations: 

• the app started once.  This was with the mini USB direct to the core, i could not repeat this behavior
• I can no longer get the miniUSB to do anything, it will start the device since the power led will fade in and out but no USB devices show up
• nothing is coming out of the midi ports
• with the main USB connected, I get the upload request over USB and feed back when I send the hex but I cannot send any other console commands to the bootloader (i.e."help" does nothing)

Does your core = the STM discovery core? As in does it take the same bootloader?

 

The bootloader is the normal MIOS one. When you "reflashed" was it with boot hold or over JTAG? It would be worth trying a) to upload any MIOS software e.g. _NG to see if that sticks or b) to wipe the chip and start again from bare metal.

Is an SD card inserted during any of this?

Does the 3v3 rail remain stable during startup?

Do you see any LED or OLED activity?

 

 

[lp1977]

@Hawkeye

Thanks for the reply and feature consideration, Peter.  That all makes sense to me.  Switching to an empty scene or muting tracks while leaving the LoopA running is an easy workaround for sending clock. Thanks. 

[Hawkeye]

@Altitude any progress? Could you try to use another computer and another USB cable for uploading? I've already had strange encounters with "cheap" USB cables and the bad windows USB MIDI drivers... If all of that does not work, could you take photos of front and backside of the core board? We'd like to know what is wrong... :) Thanks!

PS: could you try to enter bootloader hold mode and try to reflash from there? Just got this tip from Robert. You'd need to populate JPA0 and R101 and R102 on the core board and jumper JPA0 - then you should see the bootloader in MIOS studio and could hopefully try to upload again.

Best regards,
Peter

[Altitude]

ok, some more developments.

> Could you try to use another computer and another USB cable for uploading?

tried it, no change in behavior. 

>  could you try to enter bootloader hold mode and try to reflash from there? Just got this tip from Robert. You'd need to populate JPA0 and R101 and R102 on the core board and jumper JPA0 - then you should see the bootloader in MIOS studio and could hopefully try to upload again.

Just to clarify, I have always been able to see the bootloader ports and upload code.  It will occasionally (like 1 out 20 times) start the app with the miniusb directly connected to the core otherwise only the main usb goes as far as the bootloader ports showing and accepting an upload but beyond that its not working right, I cant send commands through MIOS studio.  It just does nothing when I enter commands

other things i tried:

wipe the core, reflash the bootloader with the STlink (no change in behavior)

Change the STMF407 (no change)

I finally pulled the core off and that tried that by itself and it fired right up with the mini USB (Loopa midi ports available), and normal MIOS Studio terminal behavior so it looks like the issue is somewhere on the main board that's halting the core.  Ive gone over it several times and dont see where the issue is, need a fresh set of eyes.

 

[latigid on]

Soldering looks very clean! Was the v407 breakout actually soldered in? If so, impressive that you managed to get it out so well! If it wasn't soldered in, well then the pins probably never had good contact with the LoopA-Core PCB. 

Other things: try desoldering the TVS diode and powering without it.
Also the (soldered -- brave!) optocouplers don't seem to have enough on them, would recommend a touch up.

[Altitude]

>  Was the v407 breakout actually soldered in? If so, impressive that you managed to get it out so well!

Yeah, it wasnt fun.  Hot air FTW

 

[Hawkeye]

@Altitude Thanks for the good quality pictures - soldering really is super clean! Will compare your pictures this evening with a working core PCB and report back if i see some differences.

Before you desoldered the Waveshare daughterboard, i would have guessed the STM32F4 might have been a dud, maybe bad flash memory... But if it starts up and boots the app when powered by mini USB, that's clearly working. And as you said, it must be some connection to the USB port...

Question that was probably asked before: did you have the onboard Waveshare power switch moved from "USB" to "5V In", when it was installed in the LoopA core? That's the only thing that could explain it, i think - if that switch was not moved to 5V, the Waveshare board wouldn't get proper power and would not start up when powered by external LoopA Core USB. Two red small power LEDs should be lit on the Waveshare board when all is well. You made sure of that probably, but to be sure just wanted to mention it anyways :).

If it's a hardware defect on the LoopA core or the Waveshare, we're glad to send you replacements of course, but it would be great to trace it and find the problem - thanks again for the tests and your patience!

@latigid on: could we try to trace the USB signal pins from the STM32F4 microprocessor right to the USB port on the LoopA core? Which connections would need to be tested?

Best regards,
Peter

[latigid on]

15 minutes ago, Hawkeye said:

@latigid on: could we try to trace the USB signal pins from the STM32F4 microprocessor right to the USB port on the LoopA core? Which connections would need to be tested?

Sure, already suggested: 
R30 to PA11 (yellow)
R31 to PA12 (pink)
 

Other side of the resistors:
R30 to USB 3
R31 to USB 4

[Altitude]

44 minutes ago, Hawkeye said:

..Before you desoldered the Waveshare daughterboard, i would have guessed the STM32F4 might have been a dud, maybe bad flash memory... But if it starts up and boots the app when powered by mini USB, that's clearly working. And as you said, it must be some connection to the USB port...

Question that was probably asked before: did you have the onboard Waveshare power switch moved from "USB" to "5V In", when it was installed in the LoopA core? That's the only thing that could explain it, i think - if that switch was not moved to 5V, the Waveshare board wouldn't get proper power and would not start up when powered by external LoopA Core USB. Two red small power LEDs should be lit on the Waveshare board when all is well. You made sure of that probably, but to be sure just wanted to mention it anyways :).

If it's a hardware defect on the LoopA core or the Waveshare, we're glad to send you replacements of course, but it would be great to trace it and find the problem - thanks again for the tests and your patience!

@latigid on: could we try to trace the USB signal pins from the STM32F4 microprocessor right to the USB port on the LoopA core? Which connections would need to be tested?

Best regards,
Peter

 

>..Before you desoldered the Waveshare daughterboard, i would have guessed the STM32F4 might have been a dud, maybe bad flash memory... But if it starts up and boots the app when powered by mini USB, that's clearly working. And as you said, it must be some connection to the USB port...

I thought that too so I swapped the STM chips and it behaved the same way so it wasnt the chip.  That was further proven when I took the core off and that worked by iteself.  Its something on the mainboard thats hanging it up..

 

>did you have the onboard Waveshare power switch moved from "USB" to "5V In", when it was installed in the LoopA core?

yes.

 

now that the core is off I'll trace back to the USB socket when I get some time.  Either its something stupid that I missed (likely) or some weird edge case issue (unlikely)

[latigid on]

Also that the waveshare is off, could we see that too? E.g. was the crystal desoldered, the jumpers removed, but resoldered correctly for instance?

[Hawkeye]

@latigid on thanks for the trace picture - and good idea about inspecting the waveshare! Good point to mention the crystal and cap removal and the necessary changes to the top headers there!

@Altitude I'd also recommend checking, if the connection from PA11/PA12 to the STM32F4 MCU on the waveshare board itself might be interrupted for some reason, e.g. some dodgy soldering on the daughterboard header top on the PA11/PA12 pins by Waveshare :). To check with a DMM, you could visually trace these two pins back to the STM32F4 and measure directly from the MCU pin to R30/R31 on the LoopA Core, to see if there is connectivity. Just tried this, the traces are nicely visible on the Waveshare PCB and with a loupe/magnifier you can relatively easily see where PA11/12 go to the STM32F4, then you'd just need a fine multimeter probe tip to check where those two USB signal lines are interrupted on their way to R30/R31 on the core. If there is MCU connectivity to R30/R31, a last check would be to test the USB socket itself, i've never had a fault there, but there's always Murphy's Law :).

I've also just compared pictures of your soldering with high-res video tutorial images of the board - can't really see a difference - i think it looks all good.

Many greets,
Peter

[jplebre]

I don't have much to add in terms of troubleshooting, but as Latigid mentioned, there's some bits that look like they have too little solder.

The thing that really caught my eye was D2, looks like it might be desoldered cathode end. There's a few other bits like that too on the underside (I see some bits are soldered on the upper side, so it becomes hard to see if it's a missed soldering joint or just on the other side of the board.

Good luck! :)

[Hawkeye]

Cheers - here is the new LoopA v2.07-prerelease 1 software!

Thanks to everyone sending in ideas! :) The goal remains to keep the LoopA an inspiring little sequencer that is easy to operate and not overloaded with hard-to-understand or complex features, but to implement features that improve the workflow or that are fun and usable and yet unknown to the SEQ v4+ or some other sequencers.

Prerelease notes for v2.07-PRE1:

• Added "Single Track Scene Progression Mode" (push upper-left encoder to engage this alternative scene progression mode) - e.g. it allows to cycle through all clips of a drum track without changing the other tracks' scenes. You can press and hold the SHIFT key to see which clips/scenes are played on every track. I.e. a listing of 1C, 2A, 3A, 4A, 5A, 6A would state that the played-back clip of track 1 comes from scene C, whereas all other tracks still play back clips from scene A.

• Added new "Dampen" live effect command (FX screen), that reduces the velocity of played notes of the currently active clip, similar to a dampening pedal on a piano - the applied default velocity reduction (in percent) is configurable in the setup screen, also clip dampening values can be individually configured on the FX screen (Thanks @momelq)

• Switched positions of "Faster" and "Slower" commands in the tempo screen for a more logical arrangement (Thanks @latigid on and momelq)

• Added "Screensaver = completely turn off" configuration option to reduce wear on the OLED screen in screensaver mode  (Thanks, momelq)

• "Auto session increment after initialize" (Thanks @lp1977) - Implementation note: find the first "highest" free session number slot on SD card and use that number as a session number after "new". This should prevent accidental overwrites of existing sessions with a new session.

• Bugfix: deleted notes were potentially still editable in note editor: fixed (thanks, Eugene)

Didn't extensively test yet, if you find some bugs: thanks a lot for testing and reporting - if you rely on a "stable" LoopA e.g. for live sessions, please continue to use v2.06 until v2.07 has been tested more and is released.

There will be a few more features coming to 2.07 before it is is finally released, just wanted to share what we have now. After release, the handbook will also be updated to document the changes.

Enjoy and have a good weekend!
Best regards,
Peter

LoopA-v207pre1.zip

[Altitude]

I cant find anything wrong with the connections on the mainboard, no shorts, no weird resistance.  Here's pics of the core.  Yes I am aware its set to USB (i was testing it without the mainboard)

 

Edited June 27, 2020 by Altitude

[latigid on]

There is no explanation other than a weird TVS diode pulling something up/down. I would try with that removed. You could even only resolder the waveshare with pa11/12 and the +5v pins. Can provide info when I'm back home or you can check the waveshare schem.

[Altitude]

good idea.  I want to triple check everything before I put the core back on.  I use the same diode in a couple device i sell but the list of possible suspects is getting short.