An ESP32 based foot pedal to communicate with the Spark Amp and Spark App via Bluetooth LE (iOS) and Bluetooth Serial (Android). Also works as a control device for a Looper app on the mobile. Ignitron works with all Spark Devices (Spark 40, Spark Mini, Spark GO).
Ignitron gives you full control over your Spark Amp:
- Switch between the four hardware presets
- Switch between custom saved presets organized in banks
- Toggle effects for the selected preset
- Save new presets to Ignitron via the Spark App
- Delete stored presets
- Control Looper apps on a mobile (and other apps which support bluetooth keyboard controls)
Adding new presets to Ignitron can easily be done as it can also act like a Spark Amp. Simply connect to Ignitron with the Spark App and save new presets directly from ToneCloud (or your downloaded presets) to Ignitron.
One big advantage of Ignitron is that it communicates with the Spark Amp using the Bluetooth LE protocol. This means it is possible to connect your mobile to your Spark Amp as an audio speaker and play along your favorite songs while you control your effects with Ignitron.
The current active preset and effects are indicated via LEDs.
In addition, the built-in display provides information on
- selected bank and preset number
- selected preset name
- operation mode (Preset, Manual/FX, Looper)
- activated pedal types in the FX chain
- Bluetooth connection status to Spark Amp and Spark App
This work was inspired by the Sparkpal project, and the Python Spark Parser project helped me to understand the messages being sent to and from the Spark Amp.
The following sections show how to build and operate Ignitron.
Software: click here
Hardware: click here
Ignitron has two operation modes, APP mode and AMP mode.
In APP mode (default mode on startup), Ignitron connects to a Spark Amp and behaves like the Spark App towards the Spark Amp. It can then be used to switch between saved presets, toggle FX pedals, and even connect it to a Looper app on a mobile (providing 6 buttons to control a (looper or tabs) app).
AMP mode can be used to manage the presets stored on Ignitron, presets can be saved via the app or be deleted from Ignitron. For Android, the Bluetooth mode has to be set to Serial (SRL), for iOS it has to be set to BLE.\
Keyboard mode is useful when Ignitron should act as a bluetooth keyboard control without controlling a Spark Amp. This provides 2x6=12 buttons to control any supporting app (e.g., a looper or a tabs app).
To enter AMP mode, hold the Preset 1 button during startup.
To enter Keyboard mode, hold the Preset 3 button during startup.
Amp mode and Keyboard mode can best be started by holding the respective button pressed while pressing and holding Preset 2 button to reset.
A graphical overview of all modes with button mapping can be found here. (Thanks to @itarozzi for creating this.)
In APP mode, the foot switches can be used to either switch between pre-saved presets (Preset mode), control all single effects in the selected preset (Manual/FX mode), or switch between presets while controlling an app on your mobile, e.g. a Looper app (Looper mode). You can easily toggle between Preset mode and Manual/FX mode by long pressing the Bank-Up button. To toggle between Preset mode and Looper mode, simply long-press the Bank down button.
When selecting Preset mode, four buttons are used to select presets, the other two buttons are used to navigate through the preset banks. This way the user has access to a huge number of saved presets. When pressing the foot switch of the current active preset, the effect configured in the DRIVE section can be toggled.
In Manual/FX mode, the user has direct access to all effects of the selected preset. Pressing a switch will toggle the respective FX type.
When Looper mode is activated, Ignitron acts partially like a bluetooth keyboard. You can use the buttons to control a looper app, e.g. Loopy HD, and also switch between stored presets by long pressing the Bank down/Bank up buttons. Note: When switching presets in Looper mode, it will do this across banks.
| Button | Press pattern | Function |
|---|---|---|
Bank down |
Short | Navigate bank up |
Bank up |
Short | Navigate bank down |
Preset 1 |
Short | Select preset 1 / Toggle Drive |
Preset 2 |
Short | Select preset 2 / Toggle Drive |
Preset 3 |
Short | Select preset 3 / Toggle Drive |
Preset 4 |
Short | Select preset 4 / Toggle Drive |
Preset 4 |
Long | Switch to Looper mode |
Bank up |
Long | Switch to FX mode |
Preset 2 |
Long | Restart Ignitron |
| Button | Press pattern | Function |
|---|---|---|
Bank down |
Short | Toggle Noise Gate |
Bank up |
Short | Toggle Compressor/Wah |
Preset 1 |
Short | Toggle Drive |
Preset 2 |
Short | Toggle Modulation |
Preset 3 |
Short | Toggle Delay |
Preset 4 |
Short | Toggle Reverb |
Bank up |
Long | Switch to Preset mode |
Preset 2 |
Long | Restart Ignitron |
| Button | Press pattern | Function |
|---|---|---|
Preset 1 |
Short | Sends character "1" (can be freely configured in app) |
Preset 2 |
Short | Sends character "2" (can be freely configured in app) |
Preset 3 |
Short | Sends character "3" (can be freely configured in app) |
Preset 4 |
Short | Sends character "4" (can be freely configured in app) |
Bank down |
Short | Sends character "5" (can be freely configured in app) |
Bank up |
Short | Sends character "6" (can be freely configured in app) |
Bank down |
Long | Switch to previous preset (across banks) |
Bank up |
Long | Switch to next preset (across banks) |
Preset 4 |
Long | Switch to Preset mode |
Preset 2 |
Long | Restart Ignitron |
Note: In Looper mode, Ignitron is connected to your mobile as a bluetooth keyboard. If supported by the respective app on the mobile, the buttons can be freely configured to any function offered by the respective App. You may need to manually connect to the Ignitron BLE keyboard in your Bluetooth settings after switching to Looper mode.
Example Button setup (available commands depend on availability in the respective app):
| Button | Function |
|---|---|
Preset 1 |
Record/overdub current track |
Preset 2 |
Play/pause session |
Preset 3 |
Delete current track (press twice) |
Preset 4 |
Mute current track |
Bank down |
Switch to previous track |
Bank up |
Switch to next track |
This mode will turn the Ignitron into a Bluetooth LE keyboard. All buttons will act like keyboard presses, there is no functionality regarding Preset change or other Spark Amp related functions. Use this mode if you want to only use Ignitron as a looper control device (or any other supporting app like a tabs app) . If you want to use looper control in combination with Spark Amp control, use the Looper mode as part of the APP mode (see above). In the code, multiple different keyboard layouts can be defined to support various apps. In operations, Ignitron can switch between these keyboard with the press of a button.
Every key needs be configured with the following parameters:
- Key ID (1-6 for short presses, 11-14 for long presses)
- Key code
- Modifier key (Shift, CTRL, etc.)
- Key press repetitions (0 for single press)
- String representation of key in display (should only be 1 character)
In operations, when a button is pressed, the corresponding key including modifiers will be sent to the connected device. The display will show the key representations of the currently active keyboard.
The standard defined keyboard layout will send characters 1 to 6 for short presses and characters A to Dfor long presses.
Example:
{
1,
0xD8, // KEY_LEFT_ARROW
0x81, // KEY_LEFT_SHIFT
2,
"<"
}
If a key is configured like the above, a button press will send the combination of the LEFT SHIFT and LEFT ARROW keys with 2 repetitions. In the display the key will be shown as <.
Long pressing Bank down and Bank up are reserved for keyboard layout switching.
Key codes for special keys can be found here: BLE Keyboard Library
In keyboard mode, the following keys will be sent to the connected device:
| Button | Press pattern | Function |
|---|---|---|
Preset 1 |
Short | Sends defined character (function can be freely configured in app) |
Preset 2 |
Short | Sends defined character (function can be freely configured in app) |
Preset 3 |
Short | Sends defined character (function can be freely configured in app) |
Preset 4 |
Short | Sends defined character (function can be freely configured in app) |
Bank down |
Short | Sends defined character (function can be freely configured in app) |
Bank up |
Short | Sends defined character (function can be freely configured in app) |
Preset 1 |
Long | Sends defined character (function can be freely configured in app) |
Preset 2 |
Long | Sends defined character (function can be freely configured in app) |
Preset 3 |
Long | Sends defined character (function can be freely configured in app) |
Preset 4 |
Long | Sends defined character (function can be freely configured in app) |
Bank down |
Long | Switch to previous keyboard layout (cycling) |
Bank up |
Long | Switch to next keyboard layoout (cycling) |
In AMP mode, Ignitron acts like a Spark AMP and can communicate with the Spark app running on a mobile. New presets can be stored on Ignitron and existing presets can be deleted.
Note: By default, Ignitron is configured to use BLE which only works with iOS. In order to connect an Android device, you need to switch to Serial Bluetooth. To do so, press and hold the Bank Up button when in AMP mode (after step 1. below). This will toggle the Bluetooth mode and restart Ignitron. After toggling the Bluetooth mode, start with step 1. below again. Ignitron persists the Bluetooth mode over restarts.
- Start Ignitron in AMP mode (hold
Preset 1button during startup). - Open the Spark App on the mobile
- For the first connection, make sure to have your real Spark Amp powered off to avoid the app connecting to it.
- Hit the connect button in the app (or the + button in the connection overview)
- Once the connection is established, you can give the connection a name in the app so you can distinguish from your regular Spark Amp connection.
- Start Ignitron in AMP mode (hold Preset 1 button during startup).
- Connect the Spark App with Ignitron (see above)
- Select a preset in the app (either saved in the app or from ToneCloud).
- The preset name should appear in the bottom line of the display
- The
Preset/Bankbuttons on Ignitron can be used to navigate to the desired preset position. - Press the
Presetbutton to mark the position for storing (the LED of the selected preset position should start blinking) - Hit the same
Presetbutton a second time to confirm storage (Hitting any otherPreset/Bankbutton will revert the state back to navigating) - The preset will be saved to the selected position, other presets will be pushed one position back
| Button | Press pattern | Function | Remark |
|---|---|---|---|
Bank down |
Short | Navigate bank up | |
Bank up |
Short | Navigate bank down | |
Preset 1 |
Short | Select preset 1 | Press twice to store received preset |
Preset 2 |
Short | Select preset 2 | Press twice to store received preset |
Preset 3 |
Short | Select preset 3 | Press twice to store received preset |
Preset 4 |
Short | Select preset 4 | Press twice to store received preset |
Bank down |
Long | Unload preset | Removes loaded preset if present |
Bank up |
Long | Toggle Bluetooth mode | Toggle between BLE and BT Serial mode |
Preset 2 |
Long | Restart Ignitron |
- Start Ignitron in AMP mode (hold
Preset 1button during startup). - Use the
Preset/Bankbuttons on Ignitron to navigate to the desired preset position - Long press the
Bank Downbutton to mark the selected preset for deletion - The LED of the selected preset should start blinking
- In the display you should see a prompt if deletion should be executed
- If you want to cancel the deletion, simply short press any other button
- Otherwise, long press the
Bank Downbutton again to confirm deletion. (Hitting any other button will cancel the deletion and return back to navigation)
| Button | Press pattern | Function | Remark |
|---|---|---|---|
Bank down |
Short | Navigate bank up | |
Bank up |
Short | Navigate bank down | |
Preset 1 |
Short | Select preset 1 | |
Preset 2 |
Short | Select preset 2 | |
Preset 3 |
Short | Select preset 3 | |
Preset 4 |
Short | Select preset 4 | |
Bank down |
Long | Mark preset for deletion | Pressing any other button in that state will cancel the deletion |
Bank down |
Long | Delete marked preset | Only if preset was first marked for deletion |
Bank up |
Long | Toggle Bluetooth mode | Toggle between BLE and BT Serial mode |
Preset 2 |
Long | Restart Ignitron |
This method is only recommended if a preset cannot be transferred via the Spark app or if the preset files have been received/generated in a different way.
- Create a preset file in JSON format as shown below
- Make sure the file name does not exceed 31 characters (including the
.jsonsuffix) - Put the file name into the data folder
- Insert the file name (including the
.jsonsuffix) to the desired prefix location in thePresetList.txtfile - Place the PresetList.txt file into the data folder (if not already there)
- Upload the data folder to Ignitron via the Arduino IDE (or other tools)
Ignitron stores presets in a JSON format using the SPIFFS file system. Each preset is stored in a separate file and presets are organized in a separate text file called 'PresetList.txt'. This list simply stores the file names of the presets, the order defines the way the banks are filled. An example preset file would look like this:
{"PresetNumber": 127, "UUID":"DEFBB271-B3EE-4C7E-A623-2E5CA53B6DDA",
"Name":"Studio Session" , "Version":"0.7", "Description":"Description for Acoustic Preset 1", "Icon":"icon.png", "BPM": 120.0000,
"Pedals": [
{ "Name":"bias.noisegate", "IsOn": false, "Parameters":[0.5000,0.3467] },
{ "Name":"BBEOpticalComp", "IsOn": true, "Parameters":[0.7583,0.2585,0.0000] },
{ "Name":"DistortionTS9", "IsOn": false, "Parameters":[0.1396,0.4073,0.6898] },
{ "Name":"Acoustic", "IsOn": true, "Parameters":[0.6398,0.3851,0.3834,0.5994,0.5195] },
{ "Name":"ChorusAnalog", "IsOn": true, "Parameters":[0.8417,0.2275,0.9359,0.3513] },
{ "Name":"DelayMono", "IsOn": false, "Parameters":[0.2240,0.2112,0.4909,0.6000,1.0000] },
{ "Name":"bias.reverb", "IsOn": true, "Parameters":[0.7228,0.3262,0.2758,0.3607,0.3439,0.4860,0.4000] } ],
"Filler":"23"
}
As a guidance which effect and amp names can be used and in which order the parameters of each effect have to be given, please see below.
In order to know which effects are available with paramters, see below table.
This data can be used to build own presets in JSON format (see above).
Use the Technical Name information in the JSON files.
Parameters marked with Switch can only have values of 0 or 1, others can have any value between 0 and 1.
| Type | App Name | Technical Name (JSON) | Parameter 0 | Parameter 1 | Parameter 2 | Parameter 3 | Parameter 4 | Parameter 5 | Parameter 6 | Extra Info |
|---|---|---|---|---|---|---|---|---|---|---|
| Noise Gate | Noise Gate | bias.noisegate | Threshold | Decay | ||||||
| Compressor | LA Comp | LA2AComp | Limit/Compress Switch |
Gain | Peak Reduction | |||||
| Compressor | Sustain Comp | BlueComp | Level | Tone | Attack | Sustain | ||||
| Compressor | Red Comp | Compressor | Output | Sensitivity | ||||||
| Compressor | Bass Comp | BassComp | Comp | Gain | ||||||
| Compressor | Optical Comp | BBEOpticalComp | Volume | Comp | Pad Switch |
|||||
| Drive | Booster | Booster | Gain | |||||||
| Drive | Clone Drive | KlonCentaurSilver | Output | Treble | Gain | |||||
| Drive | Tube Drive | DistortionTS9 | Overdrive | Tone | Level | |||||
| Drive | Over Drive | Overdrive | Level | Tone | Drive | |||||
| Drive | Fuzz Face | Fuzz | Volume | Fuzz | ||||||
| Drive | Black Op | ProCoRat | Distortion | Filter | Volume | |||||
| Drive | Bass Muff | BassBigMuff | Volume | Tone | Sustain | |||||
| Drive | Guitar Muff | GuitarMuff | Volume | Tone | Sustain | |||||
| Drive | Bassmaster | MaestroBassmaster | Brass Volume | Sensitivity | Bass Volume | |||||
| Drive | SAB Driver | SABDriver | Volume | Tone | Drive | LP/HP Switch |
||||
| Amp | Silver 120 | RolandJC120 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Black Duo | Twin | Gain | Treble | Middle | Bass | Volume | |||
| Amp | AD Clean | ADClean | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Match DC | 94MatchDCV2 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | ODS 50 | ODS50CN | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Blues Boy | BluesJrTweed | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Tweed Bass | Bassman | Gain | Treble | Middle | Bass | Volume | |||
| Amp | AC Boost | AC Boost | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Checkmate | Checkmate | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Two Stone SP50 | TwoStoneSP50 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | American Deluxe | Deluxe65 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Plexiglas | Plexi | Gain | Treble | Middle | Bass | Volume | |||
| Amp | JM45 | OverDrivenJM45 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Lux Verb | OverDrivenLuxVerb | Gain | Treble | Middle | Bass | Volume | |||
| Amp | RB 101 | Bogner | Gain | Treble | Middle | Bass | Volume | |||
| Amp | British 30 | OrangeAD30 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | American High Gain | AmericanHighGain | Gain | Treble | Middle | Bass | Volume | |||
| Amp | SLO 100 | SLO100 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | YJM100 | YJM100 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Treadplate | Rectifier | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Insane | EVH | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Insane 6508 | 6505Plus | Gain | Treble | Middle | Bass | Volume | |||
| Amp | SwitchAxe | SwitchAxeLead | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Rocker V | Invader | Gain | Treble | Middle | Bass | Volume | |||
| Amp | BE 101 | BE101 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Pure Acoustic | Acoustic | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Fishboy | AcousticAmpV2 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Jumbo | FatAcousticV2 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Flat Acoustic | FlatAcoustic | Gain | Treble | Middle | Bass | Volume | |||
| Amp | RB-800 | GK800 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Sunny 3000 | Sunny3000 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | W600 | W600 | Gain | Treble | Middle | Bass | Volume | |||
| Amp | Hammer 500 | Hammer500 | Gain | Treble | Middle | Bass | Volume | |||
| Modulation | Tremolo | Tremolo | Speed | Depth | Level | |||||
| Modulation | Chorus | ChorusAnalog | E.Level | Rate | Depth | Tone | ||||
| Modulation | Flanger | Flanger | Rate | Mix | Depth | |||||
| Modulation | Phaser | Phaser | Speed | Intensity | ||||||
| Modulation | Vibrato | Vibrato01 | Speed | Depth | ||||||
| Modulation | UniVibe | UniVibe | Speed | Vibrato/Chorus Switch |
Intensity | |||||
| Modulation | Cloner Chorus | Cloner | Rate | Depth Switch |
||||||
| Modulation | Classic Vibe | MiniVibe | Speed | Intensity | ||||||
| Modulation | Tremolator | Tremolator | Depth | Speed | BPM On/Off Switch |
|||||
| Modulation | Tremolo Square | TremoloSquare | Speed | Depth | Level | |||||
| Modulation | Guitar EQ | GuitarEQ6 | Level | 100 | 200 | 400 | 800 | 1.6k | 3.2k | |
| Modulation | Bass EQ | BassEQ6 | Level | 50 | 120 | 400 | 800 | 4.5k | 10k | |
| Delay | Digital Delay | DelayMono | E.Level | Feedback | DelayTime | Mode | BPM Switch |
Modes: 0.3 (50ms) - 0.4 (200ms) - 0.6 (500ms) - 0.72 (1s) | ||
| Delay | Echo Filt | DelayEchoFilt | Delay | Feedback | Level | Tone | BPM Switch |
|||
| Delay | Vintage Delay | VintageDelay | Repeat Rate | Intensity | Echo | BPM Switch |
||||
| Delay | Reverse Delay | DelayReverse | Mix | Decay | Filter | Time | BPM Switch |
|||
| Delay | Multi Head | DelayMultiHead | Repeat Rate | Intensity | Echo Volume | Mode Selector | BPM Switch |
Modes: 0 (Head 1) - 0.35 (Head 2) - 0.65 (Head 3) - 0.95 (Head 4) | ||
| Delay | Echo Tape | DelayRe201 | Sustain | Volume | Tone | Short/Long | ||||
| Reverb | Room Studio A | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.0 |
| Reverb | Room Studio B | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.1 |
| Reverb | Chamber | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.2 |
| Reverb | Hall Natural | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.3 |
| Reverb | Hall Medium | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.4 |
| Reverb | Hall Ambient | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.5 |
| Reverb | Plate Short | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.6 |
| Reverb | Plate Rich | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.7 |
| Reverb | Plate Long | bias.reverb | Level | Damping | Dwell | Time | Low Cut | High Cut | Selects Reverb Type | 0.8 |
Note: You can simply store tones using Hendrix gear on Ignitron. As the effects are licensed and purchased In-App, you need to connect your mobile Spark App to the Spark Amp after switching on the Spark Amp. When you then disconnect the Spark App and connect Ignitron afterwards you should be able to use presets using below gear.
| Type | App Name | Technical Name | Parameter 0 | Parameter 1 | Parameter 2 | Parameter 3 | Parameter 4 | Parameter 5 | Parameter 6 | Extra Info |
|---|---|---|---|---|---|---|---|---|---|---|
| Compressor/Wah | J.H. Legendary Wah | JH.Vox846 | Auto Wah Mode | BPM Mode Switch |
ms (BPM Off) | Bar (BPM On) | Sensitivity | Auto Wah Mode: 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 - Bar: 0.0 (1/8), 0.25 (1/4), 0.5 (1/2), 0.75 (1/1) | ||
| Drive | J.H. Axle Fuzz | JH.AxisFuzz | Volume | Drive | ||||||
| Drive | J.H. Super Fuzz | JH.SupaFuzz | Volume | Filter | ||||||
| Drive | J.H. Octave Fuzz | JH.Octavia | Level | Fuzz | ||||||
| Drive | J.H. Fuzz Zone | JH.FuzzTone | Volume | Attack | ||||||
| Modulation/EQ | J.H. Legendary Vibe | JH.VoodooVibeJr | Speed | Sweep | Intensity | Mix (Vibrato/Chorus) |