"They also build that do not work with wood" - Trampa: Self build MIDI footswitch.

[SamIAm]

The heart of my pedalboard is an HX Stomp, I am far from utilising anywhere near its full capabilities yet but still find its 3 foot-switches ... limiting.  (I always have one setup for tuning/mute) ... time for an extension foot-switch.  Having a rather demanding feature list and limited bank balance (I've spent too much already on my new gear) I found that then available off the shelf control units were out of reach price-wise.  I'm a "maker" and love to fiddle with electronics, 3D design/printing and software development and so was born the idea of Trampa (Swedish for tread).

 

Feature Set

• Compact so as to fit on my wee pedal board.
• 8 switch controller with digital scribble strips.
• Configurable via web interface (Acting as a WiFi hotspot running a web server).
• Support for BLE midi.
• Built in rechargeable battery.
• Not out of my price range (The bits used come in well under £100)

 

During my research I found a really cool project (PedalinoMini) that almost met my requirements and so Trampa v1 is using it.

 

I'm incorporating 4 OLED displays to support scribble strips for each pair of switches and want to be able to assign actions for when I depress two switches (For instance activating the tuner) so will need to modify the software; more likely I will do a clean room build as I also have plans to integrate it with a pedalboard based synth/looper/recorder (Think zynthian with a totally web based user interface).

 

Mock-up

I wanted something like this

 

Design

Housing design done in Fusion 360

 

Prototyping

You can see a few of the prototype prints in the next photo as I dialed in the size/layout/fitting of the front panel

 

Elements

At it's beating heart is an ESP32 microcontroller (I'm using a WROOM-32 kit board), this is an amazing powerhouse with a dual core 32-bit cpu running at 240 MHz, with onboard WiFi & Bluetooth, it has 4Mb of flash/ 520Kb SRAM and can be programmed in python or C/C++.

 

Every switch will have its own multicoloured LED (To tie in with the Stomp) and each pair will share a 0.96 inch OLED display (Crisp, clear and low power) scribble strip.

 

 

the "final" enclosure is printing at present (About 6 hours left to go) and on the morrow ... assembly.

[SpondonBassed]

Way beyond my expertise but very interesting.

 

Will the printed case be strong enough to take repeated impacts in normal use?

[SamIAm]

I find this sort of project a wonderfully satisfying fusion of design thinking (and rethinking), attention to detail, working with (and often around) software features.  Turning a concept into a visual representation and then a physical one ... and then applying it to my music ... great fun!

 

Enclosure

So after about 9 hours of whizzing and whirring

 the enclosure has finished printing.

 

Now to tidy it up. 

3D printing (certainly at my price point) does not produce perfect results, there are small bits and bobs that need to be cleaned up.  It is also possible to smooth surfaces using solvents or to sand, prime, paint ... I've yet to try these but the results I've seen have been amazing!  I "might" try and see what happens if I apply Hammerite to this enclosure ...

 

The mechanics of 3D printing (Well using this sort of 3D printing known as FDM)  are such that certain artefacts are intentionally added to the print; support material (SM) is an example of this, SM provides a scaffolding for sections printed above empty space.  Without SM the first few layers printed above an empty space would droop down before they cooled/solidified resulting in a very untidy finish. 

 

SM can be auto added in auto-magically in 3D printing software and it is printed at a lower density to make it easier to remove.

 

Without support material

 

 

With support material

 

So time to grab some tools

and do some tidying up.

 

Next step is to assemble the various components to check (fingers crossed) that they fit!

 

[SamIAm]

12 minutes ago, SpondonBassed said:

Way beyond my expertise but very interesting.

 

Will the printed case be strong enough to take repeated impacts in normal use?

The strength of 3D printed parts depends on a number of factors.

 

• The design itself; thickness of elements; supporting struts; fillets at corners to reduce stress fractures, size of faces, etc.
• The type of print material used (Some are flexible, others rigid, some come with embedded carbon fibre)
• The number of perimeters printed (and to a lesser extent the infill density and pattern)
• 

It's based on "try it and see".

 

Thicker walls with more perimeters and a higher infill density with a greater number of support struts etc will result in greater strength; this however comes at the cost of increased (sometimes significantly) print times; weight will also increase but for this project it's not a big consideration.

 

So based on my previous experience I chose a set of these factors.  Once assembled, if it is not strong enough then I can tweak the design, alter the print settings and try again.

 

S'manth x

[Random Guitarist]

Very nice project. I'm really interested to see how this turns out.

I recently bought a Bugera foot switch box for £22 on amazon with the intention of gutting it and building something similar.

I think the foot switch I got was mis-priced as it's now nearer £50, seemed like a good idea at the time but I'm not sure how I'll fit in any OLEDs . . . 

[SamIAm]

1 hour ago, Random Guitarist said:

Very nice project. I'm really interested to see how this turns out.

I recently bought a Bugera foot switch box for £22 on amazon with the intention of gutting it and building something similar.

I think the foot switch I got was mis-priced as it's now nearer £50, seemed like a good idea at the time but I'm not sure how I'll fit in any OLEDs . . . 

Nice price!  Getting OLEDs in from an electronics perspective might be tricky, physically it looks like there is no space tho.

[SamIAm]

Initial assembly

First I cut out the perspex screen protectors for the OLEDs.

Not the tidiest of cuts! (I think a "table saw" mount for my Dremel is needed ... a 3D printable one of course!)

 

They fit in nicely.  A couple of drops of superglue will hold them in place.

 

Buttons, OLED module and LEDs fit in also.

 

The inserts for mounting the base are a tad loose, a drop of superglue will sort this.

 

The ESP32 controller uses Micro USB (yuck!) for power and programming, so I'm mounting a USB Micro to USB-C panel mounted adapter.

 

First blooper! 

I goofed in positioning it, even with the buttons mounted at their extreme position (Which I do not like) it still does not fit correctly.  I'm sure that at some point I'll need to reprint the enclosure so will correct it then.

 

Next stage is to mount all the hardware (with glue as needed) and start with the wiring.  I'd love to be able to get it up and running by the end of the day.  I've spent many hours thinking/designing/testing small prototype prints over the past couple of weeks based on the following (apocryphal I believe) quotation

 

S'manth x

 

[Frank Blank]

Brilliant. Technical proficiency is just damn sexy, I can barely get the top off a boiled egg without calling the RAC (Royal Albumen Club).

Edited May 27, 2022 by Frank Blank

[SamIAm]

35 minutes ago, Frank Blank said:

Brilliant. Technical proficiency is just damn sexy, I can barely get the top off a boiled egg without calling the RAC (Royal Albumen Club).

Thank you

So long as you don't call anyone from Lilliput or Blefuscu ...

 

[Frank Blank]

55 minutes ago, Smanth said:

Thank you

 

Pleasure 

 

55 minutes ago, Smanth said:

So long as you don't call anyone from Lilliput or Blefuscu ...

I’m far to busy drifting about on Laputa.

[SamIAm]

Not as much progress made as I'd hoped .... I hate soldering so it tends to go slow and I've a few other projects on the boil that I spent some time on (One is Flo).

 

But I have got the perspex OLED display protectors mounted and the LEDs are mounted and soldered up (Just need to test all the hookups are sound ... tedious but not onerous).

The footswitches are half soldered (Yech more soldering!) and once I'm sure the LEDs are hooked up correctly I can mount the switches.

 

S'manth x

[PaulThePlug]

Watching with interest....

Enough plastic 'meat' to file a bit off the cable YSB socket to clear the switch.

[Andyjr1515]

Impressive stuff on many fronts.  I read with interest the challenges with 3d printing...but that is a high quality result by any measure!

[SamIAm]

The LED wiring seems sound (No circuit shorts or breaks) tho I won't really know until I've hooked it all up.

Foot-switches mounted.  The pins soldered on the switches are to allow me to use solderless connections (A bit like EMG do) to interconnect everything.  As this is the first prototype build it gives me more flexibility to modify the circuit; this will be very handy when I come to the modification for the multiple OLED displays.  I've only installed one OLED at present as the current software does not support more; I will either need to modify it (It is open source) or more likely write my own to replace it.  A rewrite is a bigger job but I have dreams of a sound chain management eco-system (You can tell I was once an IT Consultant!) that incorporates midi control (wired and BLE), a synth/looper box (Occasionally some backing drums would add to our songs and I really fancy trying to get a midi signal out of my axe to drive a synth) and a HX Edit type editor.  All talking to each other and to my Stomp.  All available to view and configure from a web based interface (Tablet mounted on my mic/music stand) 🤔 but just for now ...

With all the switches in, trampa has a lovely heft to it.

 

Next will be final wiring, testing, flashing the firmware, testing, initial configuration, testing and then trying it for real (Well, with my gear in the living room) ... I am determined that I'll have it operational before band practice on Wednesday

 

S'manth x

 

By the way, the squares on the green cutting board are 10mm x 10mm.

Edited May 29, 2022 by Smanth
Added dimensions of cutting board squares

[Velarian]

Mind blown! 🤯

[Richard R]

Very cool. 😎

[velvetkevorkian]

This is amazing. I long ago accepted that I don't have the temperment for hardware tinkering but a web UI for effects is a really neat solution (and is giving my web dev brain some ideas to chew on...). Is the board effectively a wee Linux box that you can run a server + the microcontroller stuff on, or do you have to package it all up somehow, a la Arduino?

[SamIAm]

1 hour ago, velvetkevorkian said:

This is amazing. I long ago accepted that I don't have the temperment for hardware tinkering but a web UI for effects is a really neat solution (and is giving my web dev brain some ideas to chew on...). Is the board effectively a wee Linux box that you can run a server + the microcontroller stuff on, or do you have to package it all up somehow, a la Arduino?

 

The chip at the heart is the rather amazing ESP-32 which incorporates a number of elements that are useful in the IOT (Internet of Things) space; the ESP seems quite revolutionary in packaging all of these in a single chip.  

The Core contains a pair of microprocessors that can run freeRTOS (think a micro linux).

 

The chip is widely available on boards like this

that provide a USB interface (for programming/debugging) as well as access to many of the I/O pins on the chip.

In small quantities they are about £10 each!

 

Programming the system can be done using the Arduino toolkit and there are many libraries available to do things like read a switch with debounce, drive a LCD/OLED display chip, connect to WiFi, send data over bluetooth and so on.  It is also possible to load a python system (micropython or circuitpython) on the chip; it then appears as a USB drive on your computer ... writing a python file (or set of them) to the USB drive and the chip will run them.  As with the arduino toolkit, there are many libraries available.

 

My preference is to use the development system offered by the chip manufacturer Espriff, called ESP-IDF.  It is more technical in nature but provides better access to low level stuff in the chip and in a more effective fashion; this chip can do crazy things like face/voice detection, connect to AWS IoT Core, Azure IoT and Google IoT Core cloud, even DSP.  Amazon Echo devices have something like this in them.  Development can be done using Eclipse or VSCode and there are plugins available for these to make this easy.

 

I started work in IT in the 80s; my first 'real' computer was a ZX-81; they were exciting times.  I stumbled into the world of microcontrollers just a few weeks ago (I retrained as a nurse in 2015 so have not been as hands on with IT as I used to be) and the capabilities just blew my socks off!!!

 

There are a vast number of resources on the web about working with these type of devices, RandomNerd is quite a good one.

 

S'manth x

 

 

 

 

 

Edited May 29, 2022 by Smanth
Fixed typo

[ezbass]

I’m no stranger to a component and some solder, but this not next level stuff, this the level after the level after that one. Impressive stuff, but you’re speaking another language now, not just a programming one either. 

[SamIAm]

Controlboard wired in

OLED display wired in

USB connection to controlboard successful and firmware uploaded.

Initial configuration to connect to WiFi SamFi.

System powered on and ...

The video shows Trampa successfully connecting to SamFi.

Pointing a web browser at Trampa displays the basic system info

 

Looking good so far!

 

Now to hook up the footswitches and LEDs

 

 

Edited May 29, 2022 by Smanth
Removed duplicate image

[SamIAm]

 

 

 

Working sufficiently well for band practice Wednesday, tho I still need to print a bottom cover for the enclosure before then and get it Velcroed to my pedalboard (That's why I had to hold it down for the video).  The item in the top right is a USB battery bank that is powering the Trampa; I'd like to be able to drive the Ant, the Stomp and Trampa using one of these so I am not tied to mains power.

 

Next

At 21s in the video the name of the switch pressed shows up well.  This is the type of label I want displayed adjacent to every switch in a scribble strip fashion (Like my mockup image)

This will require a change to the wiring to add in the missing OLED panels as well as getting the software to support them.

 

Add in a battery charging module as well as an internal battery.

 

The LEDs work (as can be seen during startup) however I cannot see how to configure them in the way I want at present; software modification required.

 

The Pedalino s/w that Trampa is currently running, whilst really rather cool, has some features I am unlikely to ever need and is lacking some features I do.

 

As I mentioned before, I have a couple of other projects in mind that will allow tighter integration with the Stomp (Like HX Edit can); I'm playing with Patchbox with a view to building some sort of synth, recorder, looper, drum machine, sound F/X thing and it would be nice from a design perspective to have a uniform user interface across all of these modules.  As such I am likely to develop new software to run Trampa and its siblings.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[SamIAm]

The end of chapter one.

I printed the bottom cover for Trampa last night.

 

The USB adaptor fits nicely this time 😭

 

The old hole (to the right) can stay ... I think at some point I will print the main enclosure again, but with 3mm walls instead of the current 2mm; this will depend on how Tramp holds up under use.

 

12mm M3 bolts seem to be the right size.

 

Using a soldering iron set to 200c (The working temp of the plastic filament used in the enclosure is 220-230) I set the receiving mounts in the body.  The holes printed are smaller than the mount diameter so that they will melt into place; the hole was designed to be deeper than required to take the M3 bolt, this was to allow space for any molten plastic to 'escape' ... otherwise it might ooze up through the mount and block the thread.

 

Attach the cover

 

Apply some magic Velcro

 

And like magic ... ready for band practice this afternoon.

 

I'm using an external USB battery for now, it's handy as it shows remaining charge ... and it fits nicely under the wireless guitar cable receiver.

 

Now to try it out, see how it holds up, figure out the best configuration for gigs.

 

At some point I will install the additional OLED displays and update the hardware/software to support them; for now ... time to practice some more chord tone patterns 

 

S'manth x

 

[Andyjr1515]

That is crazy good...

[SamIAm]

26 minutes ago, Andyjr1515 said:

That is crazy good...

Thanks Andy, I'm rather pleased with it!

 

Dimensions:  85mm deep, 190mm wide, 45mm high (60mm to top of switches)

Weight: 380g

Configuration: Using the built-in webserver from a browser on computer/tablet/phone.

Power: External USB via USB-C port

Wifi: Built in, can connect to WiFi hub or act as a standalone unit (For instance if I need to reconfigure it at a venue)

Midi over BLE: Built-in

 

The various mechanical bits and bobs (switches/etc) cost about £25

The various circuit boards (ESP-32/OLEDx4/OLED Multiplexer/etc) £32

Connector wires, perspex, tools (Dremel,3D printer) and assorted stuff (filament, bolts/mounts) I had to hand

So all in well under a ton in parts, much more cost effective than buying one off the shelf (If you could even find something with it's capabilities![*]) and I can get it to do anything I want!

Well worth building one if one has the skills (or can find someone here on BC who would do it for you )

 

[*] I did not need all the capabilities that the PedalinoMini™ supports, which are listed as:

• Plug-and-play with any MIDI-compatible app on iOS 8 and above as well as OS X Yosemite and above.
• High customizable using web interface
• Bluetooth, WiFI, USB and legacy MIDI interfaces
• No extra drivers to connect Windows, macOS, iOS (iPad/iPhone) and Android
• Bluetooth LE MIDI (iOS and macOS compatible)
• Network MIDI (aka AppleMIDI or RTP-MIDI)
• ipMIDI
• Open Sound Control (OSC)
• IEEE 802.11 b/g/n Wi-Fi 2.4 GHZ with WPA/WPA2 authentication
• Bluetooth Low Energy 4.0
• DIN MIDI IN and MIDI OUT connectors
• MIDI routing
• MIDI clock master and slave
• MIDI Time Code (MTC) master and slave
• OSC to MIDI and viceversa
• Any number of pedals of any type in any order
• Auto-sensing footswitches and expression pedals

The range of 3rd party pedals that can be connected in is amazing!

 

S'manth

[SpondonBassed]

Thanks for sharing.  Inspirational thread.

 

I'd like to think that, in another life, I would be doing similar projects.