Yet Another Pedal? Meet PENDA!

Hardware Development
1

Hey everyone,

I know, I know… another pedal project, right? :smile: But stick with me for a second because PENDA (Platform for Effects oN DAisy) brings a few cool twists to the table!

What makes PENDA different?

  • 100% Analog Dry Path: Yep, the dry signal stays fully analog to preserve your tone’s integrity while still offering powerful digital effects.
  • Large 2-inch SPI Display: Bigger screen, more room to tweak and see what’s going on. Perfect for navigating complex settings or just showing off cool graphics. :sunglasses:
  • 4 Encoders with Pushbuttons: More control at your fingertips—literally! Easily dial in precise adjustments without feeling cramped.

The whole design is based on the Daisy Seed board, but with these added features, I think it stands out in its own way.

What do you think?

I’d love to hear your feedback and ideas! Don’t hesitate to challenge my design. I’m open to suggestions, improvements, or even completely new ideas. Let’s make this pedal as versatile and powerful as possible!

Feel free to check out the project on GitHub PENDA Hardware : https://github.com/DADDesign-Projects/PENDA-Hardware

Looking forward to your thoughts!

Cheers,
Philippe

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2

Have you built any of these?

3

Yes, I have built a working prototype of the PENDA pedal, and … it works well! Currently, I am working on a delay and a looper, but I don’t have anything presentable yet.
Philippe

Small video : https://github.com/DADDesign-Projects/PENDA-Hardware/blob/main/Images/PENTA.mp4

Image :

PENDA V1.0
PENDA V1.0664×652 41.5 KB

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4

This is looking awesome!! Keep us all posted :slight_smile:

5

Very cool! Do you have any C++ samples how to initialize and use the OLED display?

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Hi! Yes,
I’ve already published a post on this topic.

You can find the code on my GitHub here:
https://github.com/DADDesign-Projects/DEMO_DaisyGFX_ST7789 .

Philippe

1 Like
7

Haha, analog DRY path FTW.

8

Hello,
I tested the sound quality between the dry and wet (unprocessed) signals, and although the difference is subtle, it is very real! The dry signal has a bit more bass and slightly better definition.
Philippe

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Oh, I’m totally with you. Why would you not have an analog dry path, its just silly to do it any other way. And it makes it super-easy to split your outputs if you’re lucky enough to be running separate wet & dry amps.

10

Probably a stupid question, but isn’t the OLED displayed reversed?

11

Bonsoir
I’m not sure I understand your question clearly. Are you asking about the electrical connections? If so, I’m using a 2-inch LCD Display Module with an IPS screen, 240×320 resolution (it’s not OLED). The connection order on this module is actually reversed compared to similar screens.

Philippe

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The connecting pins are on the left side of the screen. However, in your pedal the connecting pins are on the right side of the display. This makes me think you display image is rotated by 180 degrees, is that true?

13

Bonsoir
Yes, you could say the screen is rotated by 180°, but that’s really just a way of looking at it—the screen itself doesn’t have a specific “right-side up.” In my graphics library, there’s a function called setRotation(angle) that allows me to set the XY coordinate reference frame of the screen however you like.

Philippe

1 Like
14

If you don’t mind yet another question - what enclosure size/type are you planning to use?

Thanks

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Hammond 1590BBS.
Philippe

1 Like
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PENDA Software

Hello everyone,

I have just released a software framework dedicated to the PENDA Hardware platform. This framework is designed to simplify the design and manufacturing of audio effect pedals by handling both hardware aspects and the user interface.

Key Features of PENDA Software:

  • Comprehensive Hardware Management: Supports audio CODEC, SDRAM and QSPI memory, TFT display (ST7789), and interaction with footswitches and encoders.
  • Integrated User Interface: Provides advanced, configurable GUI management tailored for PENDA Hardware.
  • Built on STM32Cube: Utilizes a modular and extensible architecture within the STM32Cube development environment.

The goal is to allow developers to focus solely on audio signal processing, without needing to manage hardware configuration or display handling.

I would love to hear your feedback on the user experience and see the projects where PENDA Software could be used! Feel free to contact me for any questions, suggestions, or bug reports.

:pushpin: More info & source code: GitHub Repository

Thank you, and I look forward to exchanging ideas with you! :rocket:
Philippe

Penda_1
Penda_1400×297 94.1 KB

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17

Hello everyone,

Just a quick update to let you know that I’ve released a new version of the PENDA Software framework, which now includes MIDI protocol support.

I’d love to hear if you’ve started exploring or developing projects using this framework—feel free to share your experiences, feedback, or suggestions.

As an early preview: I’m currently working on PENDA MKII, a stereo version of the original platform. More details coming soon!

See you soon,
Philippe

3 Likes
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Announcement: New PENDA Software Release — Tremolo/Vibrato and Delay Effects

Hello everyone,

I’m happy to announce the release of a new version of the PENDA Software project, developed around the Daisy Seed platform.

This version introduces two new audio effects:

:control_knobs: Tremolo/Vibrato

  • Low Frequency Oscillator (LFO) with adjustable speed and two selectable waveforms.
  • Adjustable duty cycle to modify the LFO waveform shape.
  • Independent control of tremolo (amplitude modulation) and vibrato (frequency modulation) effects.

:control_knobs: Delay

  • Main delay adjustable from 0.100 to 1.5 seconds.
  • Secondary delay available with rhythmic subdivision options.
  • Modulation applied to delayed signals for subtle “chorus/flanger”-type effects.
  • Independent bass and treble control on echoes to fine-tune their tonal character.

:pushpin: More info & source code: GitHub Repository

Please feel free to share your feedback, suggestions, and questions!
I’d also be very happy to hear about your projects, your experiments, or how you might be using (even partially) this framework.

Looking forward to your updates! :rocket:

2 Likes
19

Very cool. I like the use of more rotary encoders :slight_smile:

I may have to try and build one! \o/

I didn’t really examine the hardware apart from the images here and on github. Are there any changes in the pipe or is this the “final” version? (Oh, i just read there is a stereo version coming anyway, cool!)
Some of the other hw designs have some issues with noise in the signal chain, how does this one fare in this regard?

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Hi everyone,

Thanks a lot for your feedback!

The current versions of Penda Hardware and Penda Software are pretty mature and working very well.
I don’t really have the means or the time to make demo videos yet, but the first effects (delay and tremolo) are, in my opinion, already very satisfying.

Of course, I’m still working on expanding the framework, but at this point, it really makes it super easy to develop new effects.
For example, the tremolo/vibrato effect only needed around 150 lines of code.

I haven’t had much feedback on the forum so far — I’m not sure if anyone else has built a Penda yet, or if people are interested in the concept.
My secret hope is that the community will eventually help build a nice library of effects around the Penda and its framework. :blush:

About noise:

It’s always tricky to balance high input impedance and high gain.
For the Penda, I decided to limit the input impedance to 220 kΩ, which is enough even in tough cases, like plugging a guitar straight into the pedal.
(Some other designs use 1 MΩ input resistors, which can add quite a bit of noise.)

Other than that, it’s important to avoid using resistors with too high values, to take care of the power supply, proper decoupling, and so on.
On the two Penda units I built, I have no noticeable noise problems.
Of course, like with any pedal, you still need to be careful with the power supply you use and how you handle ground loops — the usual stuff!

The upcoming Penda mkII stereo won’t replace the original Penda, it will just complement it.

  • Penda 1 is simple and very easy to work with.
  • Penda II will be much more complex: built with hand-solderable SMD parts, better power supplies, and a dry/wet control using digital potentiometers (but the audio path will stay fully analog).

The Penda mkII will stay 100% compatible with the framework.

PENDA MKII
PENDA MKII800×600 149 KB

Cheers and thanks again for your interest!
Philippe

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