pi-Stomp is a high definition multi-effects stompbox platform for guitar, bass and keyboards. The base install contains over 380 open source plugins - effects, modeled amps & cabinets (via NAM plugin), loopers and sound generators (synths). From the webui, the user can manage the set of installed plugins and install additional plugins from the Patch-Storage cloud.

The hardware built from a kit sports 24-bit, 48 to 96kHz stereo audio and a Raspberry Pi5 64-bit quad core processor running at 2.5 GHz.

Numerous virtual pedalboards containing up to dozen (or so) plugins, can be constructed via MOD, a super powerful yet easy to use drag-n-drop web user interface. Each pedalboard can be saved with multiple “snapshots” (aka “presets”), each being a snapshot of all the parameters for a given sound.

Once your pedalboards are saved, only the pi Stomp is needed on-stage, at home or in the studio.

An LCD shows an overview of the current pedalboard. Navigation is done via rotary encoder and allows quick changes of the pedalboard, preset, plugin bypass, deep plugin editing and global settings.

The original pi-Stomp was the first DIY HD Multi-FX platform available in kit form. Over 160 pi-Stomp pedals have been built in 20+ different countries!

The newest v3.0 upgrades processing power with support for Raspberry Pi5 so it contains one of the most powerful quad-core processors available any any multi-effect unit.

A few important things to know if ya just wanna get making music

• In1 and Out1 are the jacks to use if you just have a mono instrument
• First boot will take a while, give it a minute or two (later boots should take just over 20 seconds)
• If the audio sounds distorted (in a bad way) or the input clipping LED's turn yellow or red with normal playing, adjust the input gain by scrolling using the Navigation knob, selecting the blue Audio menu (top right), click, select “Input Gain” and turn it down until loud strums no longer distort or turn the LED red.
• Access the webui editor (MOD-UI) by pointing a browser on your computer/tablet/phone to pistomp.local

Plugins are software units (LV2 specifically) which provide some type of function on a Pedalboard. The function might be audio processing (eg. “effects”), audio generation (eg. “synths”), MIDI manipulation, etc. The set of plugins for the currently active Pedalboard are shown on the main home page of the LCD.

Plugin Parameters are the settings used to control the behavior of a plugin. A Distortion plugin might have a “Gain” or “Volume” parameter. Most plugins include a “Bypass” parameter to control whether the plugin is active. Most Parameters can be assigned to a physical control (eg. Tweak knob or footswitch) or to an externally connected MIDI control.

A Pedalboard is a combination of Plugins and cable routings, together forming a virtual music equipment setup. There is always one pedalboard active on the device. The current Pedalboard name is shown at the top of the main home page of the LCD and can be changed by navigating to that name, then clicking.

A Snapshot stores the state of all plugin parameters on a pedalboard. Each Snapshot is specific to the pedalboard it was created for. Each Pedalboard has a Default Snapshot. Snapshots can be used to specify different scenes, parts of a song (verse, chorus, bridge, etc.) where the set of plugins don't change, but the settings do change between Snapshots. The current Snapshot name is shown at the top of the main home page of the LCD and can be changed by navigating to that name, then clicking.

A Bank is a collection of pedalboards used as a means of organizing them for easy access. A single pedalboard can exist in multiple banks. Deleting a Bank does not delete the pedalboards inside it. Banks are useful for focusing on a subset of pedalboards instead of the entire set of pedalboards on the device. Since the pedalboards within a Bank are ordered, usage of Banks makes scrolling thru pedalboards in a user defined order easier, as might be desirable for setting up a performance setlist. The current Bank can be changed via the System menu. The default mode is for no Bank to be active, meaning that all pedalboards on the device will be shown during pedalboard selection.

The pi-Stomp LCD screen shows the state of system and the current pedalboard. The Navigation encoder knob is used to interact with the LCD (kindof like a computer mouse).

• Turning the encoder, scrolls thru the elements on the screen (Tools, current Pedalboard, current Snapshot, plugins, menu selections, etc.)
• Clicking the encoder takes action on the selected element
  • When the Pedalboard is highlighted, clicking enters pedalboard selection mode. Scroll now to select a new pedalboard, click again to load it
  • When the Snapshot is highlighted, clicking enters snapshot selection mode. Scroll now to select a new snapshot, click again to load it
  • When a Plugin (or footswitch) is highlighted, clicking toggles the enabling of the plugin
  • When the bypass/processing tool is highlighted, clicking toggles the state
  • When the System tool (wrench icon) is highlighted, clicking switches to the System Menu
• Long Press goes deeper or exits current mode
  • From the main screen, long press will bring up the System Menu which includes various utilities for managing your system
  • When a Plugin is highlighted, long press enters “Deep Edit” mode for changing the parameter settings of that plugin

Except for the Navigation encoder, the other 3 encoders and 4 footswitches are user configurable. Configuration requires an ssh connection and is specified via the file at: /home/pistomp/data/config/default_config.yml

The syntax is YML.

• Rotation: Sends MIDI_CC message (default: 70)
• Switch Click: accept setting

• Rotation: Sends MIDI_CC message (default: 71)
• Switch Click: accept setting

• Rotation: Adjusts output volume level

Note: this control can optionally be mapped to be a MIDI_CC tweaker by editing default_config.yml

The footswitch single click operations are typically used for Plugin enable/disable

• Click: toggle midi_CC between 0 (off) and 127 (on) (default CC: 60)
• Longpress: Previous Snapshot
• Combinations:

• Click: toggle midi_CC between 0 (off) and 127 (on) (default CC: 61)
• Longpress: Next Snapshot
• Combinations:

• Click: toggle midi_CC between 0 (off) and 127 (on) (default CC: 62)
• Longpress:
• Combinations:

• Click: toggle midi_CC between 0 (off) and 127 (on) (default CC: 63) OR Tap Tempo (when in Tap Tempo mode)
• Longpress: Toggles to Tap Tempo mode
• Combinations:

1. Rotate the Navigation encoder until the current pedalboard name is highlighted (in yellow)

2. Click the encoder to show a menu of available pedalboards

3. Rotate the encoder to choose (highlight) the desired pedalboard

4. Click the encoder to load it

Note that loading the new pedalboard could take a few seconds

1. Rotate the Navigation encoder until the current Snapshot name is highlighted (in yellow)

2. Click the encoder to show a menu of available snapshots

3. Rotate the encoder to choose (highlight) the desired snapshot

4. Click the encoder to load it

1. Rotate the Navigation encoder until the plugin block is highlighted (in yellow)

2. Click the encoder to toggle between “Enabled” and “Bypassed” state

An “Enabled” plugin shows with a “filled in” block. A “Bypassed” plugin shows as an “unfilled” block.

Note that the visual representation of bypass state is not synced between the MOD-UI and the pi-Stomp LCD until the pedalboard is Saved.

1. Rotate the Navigation encoder until the plugin block is highlighted (in yellow)

2. Long Press the encoder until the Parameter selection menu displays

3. Select the parameter, click the encoder

4. Adjust the parameter setting by rotating the encoder (takes effect immediately)

5. When done, close dialog by clicking the encoder

To enter Tap Tempo mode, press-and-hold Footswitch D (the right-most) until the label for it changes to a number (likely 120 if you've not already set a tempo for this pedalboard)

Now tap the same footswitch at least 4 times to the tempo you desire. The number should change to show the determined tempo. You can re-tap a tempo sequence if needed.

Once done, press-and-hold the footswitch to return to default footswitch mode (plugin enabling, etc.)

To have the new tempo used everytime you load the pedalboard, you'll need to save the pedalboard:

System Menu > Pedalboard Management > Save current pedalboard (or Save function in MOD-UI)

The Wi-Fi status is indicated by the color of the Wi-Fi toolbar button

Wi-Fi Mode, Not connected

Wi-Fi Mode, Connected

Hotspot Mode

To switch modes or configure Wi-Fi click on the Wi-Fi toolbar icon to get to the Wi-Fi Menu

Configure WiFi sets the SSID and password for you local router

Selecting eithier field and clicking brings up the “virtual keyboard”

Longpress will toggle between lower-case, upper-case and symbols

When done editing, click the green checkmark

Global audio settings are available via the Audio toolbar button.

To view or change settings, Long-press the Audio toolbar button.

Audio Processing can be bypassed for one or both channels.

The Bypass/Enable toolbar button shows the current status.

Clicking the toolbar button will toggle processing on/off

To change the channel bypass preference, Long-press toolbar button.

Most users will prefer Left & Right bypass

The System Menu contains a variety of system level functions

The Hardware Usage guide above, demonstrates how to perform the basic pi-Stomp functions on the set of pedalboards stored on pi-Stomp. Eventually, you'll probably want to create your own pedalboards or at least modify (edit) the ones already on it. For those operations, we need a higher level graphical interface than the LCD can provide.

With your pi-Stomp connected either in hotspot or Wi-Fi mode, point a browser on your computer to pistomp.local/

The MOD Web UI was created by MOD Devices. The guide below is intended for their hardware (Dwarf and Duo) but most of the UI details pertain to pi-Stomp as well.

MOD Web UI User Guide

Any plugin parameter can be controlled by MIDI CC messages coming from a pi-Stomp footswitch, tweak knob or external MIDI controller. Assignment of the parameter to the physical control is done via the MOD-UI.

IMPORTANT: Due to a quirk of the MOD software, once an physical control is assigned to a parameter on a pedalboard, it cannot be reassigned to another parameter without first unassigning it from the original. That will be the case for any of the default pedalboards that have footswitch or tweak-knob assignments. See instructions below on how to un-assign.

Open the Settings dialog for the plugin

Under the parameter to assign, click the parameter modify button

Select “MIDI”, then “Save”.

Now turn the knob, push the footswitch, adjust the MIDI controller, etc. And if that actuator sent a MIDI CC message, the parameter should now be assigned/mapped to that plugin parameter. Look for a confirmation dialog in the upper right.

To retain this assignment, make sure you then Save the pedalboard.

If you are not seeing a confirmation. Make sure your physical control is not already assigned to another parameter (see “Un-Assigning a Control” below). Also make sure that your MIDI mode is set to “Separated” NOT “Aggregated”

There is an “Advanced” option on the modify dialog. That doesn't offer anything interesting for toggle parameters like plugin bypass, but for continuous controllers, you can specify a different range than the default for the parameter.

Say the default Drive range was 0 thru 10. Maybe you never want your drive to be that low. You could set the low value to 5. After assigning to a tweak knob, with the knob at full counter-clockwise the value should now be 5 giving you only the values that are useful to you and providing finer control over that range.

Because a control can't be assigned to a parameter if it is already assigned to another parameter on the pedalboard, you must first un-assign.

Once you find which plugin and parameter the control is currently assigned to, open the modify dialog:

Now click “None”, then “Save”

There is no confirmation, but if the un-assignment worked, you should then be able to reassign the physical control to another parameter.

–

Yes, as a small team project, we admit, there are shortcomings. Many of these are due to the MOD software being developed by MOD Devices for their own hardware. They were gracious enough to open source it, but pi-Stomp just doesn't have all the “hooks” they were able to add specifically for their hardware. In the future, we will try to add our own hooks. For now, here's a heads-up of what to expect.

• Most actions made via the MOD-UI will not be shown on the pi-Stomp LCD. Switching pedalboards or saving a pedalboard will resync the LCD to show the current state of the pedalboard. So it's best to edit away using the MOD-UI knowing that once you save, the pi-Stomp LCD will resync.
• Similarly, some changes made on the pi-Stomp won't be reflected in the MOD-UI. Specifically plugin bypassing and parameter tweaking via the Navigation knob. MIDI assigned bypass (eg. Footswitch) and parameters assigned to the Tweak knobs Will show in real-time in the MOD-UI.
• For the above reasons, we generally recommend editing your pedalboards via MOD-UI, then saving and using the physical pi-Stomp controls for Live changes.
• Externally connected MIDI controllers can be mapped just like the onboard footswitches and tweak knobs. You will see the changes reflected in the MOD-UI in real-time, but bypass toggle events won't similarly be reflected on the LCD.

If you are seeing other strange behavior, see the Troubleshooting Guide

The pi-Stomp operating system is a custom Raspberry pi, Debian based, operating system.

You can easily modify the pi-Stomp specific code (mostly python), install additional packages, etc. but please start with an official pi-Stomp release and don't try updating or upgrading the base OS by running the typical “apt-get update” and/or “apt-get upgrade” commands. This could cause problems with your system.

You might wish to make a backup of your pedalboards and/or user data for safe keeping or to transfer to a different pi-Stomp SD card.

Restoring won't clobber pedalboards or data on the new system, it will instead just add pedalboards not yet existing on that system.

Insert a USB drive (500MB or more) into the pi-Stomp (raspberry pi) USB port

Create a zip file backup of your data onto the USB drive:

ssh pistomp@pistomp.local
sudo mount /dev/sda1 /media/usb0
[ ! "$(mount | grep /media/usb0)" ] && echo "Mount failed!" && exit
sudo mkdir -p /media/usb0/backups
sudo zip -rq /media/usb0/backups/pistomp_backup.zip /home/pistomp/data -x "/home/pistomp/data/.lv2/*"

That takes a minute or two. Once it completes run the following

sudo umount /media/usb0

Once that completes, you can pull the USB drive

To restore the backup onto a new pi-Stomp install: Insert the USB drive which contains the backup

On the pi-Stomp LCD, navigate to the System Menu (wrench toolbar)

Select “Pedalboard Management >”

Select “Restore Backup data” (this can take a few minutes)

• pi-Stomp v3 Build Instructions
• Software Installation Guide
• Troubleshooting Guide
• Previous pi-Stomp hardware versions
• Developers Guide

• Task specific Tutorials and Videos

• Tone3000 (Best resource for thousands of models)

• pi-Stomp software and firmware

• pi-Stomp Bug/Issue/Feature-request Tracking

• pi-Stomp starter pedalboards

• mod-host plugin host software (Created by the great folks at Mod Devices)

• mod-ui web ui (Created by Mod Devices)

• MOD SDK

• How to build and deploy an LV2 Plugin. We generally recommend using the docker image to avoid build issues.

• pi-Stomp Forum
• facebook.com
• instagram.com
• hackaday.io
• Pedal Haven

Tree Fall Sound exists to bring multi-effects projects to DIY musicians.

My “day jobs” have been in Electrical and Software Engineering, but my main passion has always been music. I’ve been building effects pedals and other musical gadgets since the 1980’s (read “experienced”, not “old”). I’ve always been obsessed with tone, usability and clever features.

How cool would it be to create a do-everything open expandable effects platform, easily modifyable by anyone not too afraid of Linux, Python, etc. ? That's the idea that got me rolling on this project. Raspberry Pi and high def sound cards along with some open source software like LV2 (plugin format) and MOD (plugin host and UI), have finally made such an endeavor possible.

I created this project because I know there are others like me that would be waaay more excited playing with a piece of gear they built and can modify by getting under the hood of the hardware and software. I spend well over 20 hours on it every week and will continue to as long as there is new functionality and features to explore. I’m hoping others will join us in this endeavor and take their creations to places we've not even imagined.

Stream some of my original music here via your platform of choice: https://artists.landr.com/055120649103

An extensive interview and more pi-Stomp background on Blokas Reads

I’ve been into electronics and taking things apart since before I could walk. My passion for electronics really took off when I started to play guitar at age 13. By age 15 I got bitten by the tube bug and built my first tube amp. The case for tone had begun. After getting tired of lugging amps and massive pedalboards around, I decided to look into making something digital. I stumble upon pi-Stomp and I was hooked.

I have a background in IT and Linux sysadmin, so naturally my focus has been on the OS and core software, where I continue to try and squeeze every last drop of performance and efficiency out of what we have.

We love the Earth and hope you do too. Electronics are inherently not good for our planet. Our hope is that by building something yourself that can be upgraded, you'll be able to make use of it longer than you would have a commercial product, and that you might be able to reuse or recycle many of the components when its life is truly over.

• All pi-Stomp PCB's are Lead Free HASL RoHS compliant.
• Any presoldered parts were soldered with Lead Free RoHS solder.
• All board components are RoHS compliant.

The only non-RoHS compliant components in the current design are:

• The TFT Color LCD
• The AudioInjector audio card

When you are done with your pi-Stomp, please consider using the Raspberry Pi, LCD, etc. for other projects or donating them to your local Makerspace.

If you eventually dispose of your pi-Stomp components, please do so according to your local guidelines. Removing the non-RoHS parts shown above to deal with them appropriately is encouraged. Thanks!

The Internet is a huge polluter of the environment.

treefallsound.com is hosted by GreenGeeks

The carbon footprint is reduced (not offset) by matching every amp they pull from the grid with 3 times that in the form of renewable energy via Bonneville Environmental Foundation. They also plant one tree for every hosting account they provision.