Drum Machine Version 2.1 (circa June 2018)

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I haven’t worked on my Drum machine for a long time. So in order that I don’t forget what I did I’m writing it down. As I write these posts I realise what a lot of dead-ends I have gone down…

This design was created in early 2018 and was intended to be an expanded version of the first PIC32 design with a some specific goals.

  • Create larger device with a less cramped interface than earlier versions
  • Use a better/bigger display for both for better visibility and also to display more information
  • Add a rotary encoder for additional input (I hacked one in as a test on the old design and it was quite useful)
  • Use a “proper” Digital to Analogue Convertor (DAC) in place of Pulse Width Modulation (PWM) plus R/C filter used in the previous design for better quality audio
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ChipStomp – Source code

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A quick update to say that I have released version 1.0 of the source code for the ChipStomp.

I’ve spent a fair bit of time making sure that the source is documented in the areas that are less clear and I have removed all redundant/experimental code in an attempt to avoid confusion with things I haven’t finished yet.  That took a lot longer than I would ever have imagined.

You can find the entire project including the Eagle CAD schematics and Layout up on GitHub.

Chipstomp assembly – Analogue side

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Fully assembled and working Chipstomp

Fully assembled and working Chipstomp

It’s done.  I’ve assembled the analogue side of the Chipstomp and finally have a fully working device.  There were no errors to fix this time which was a nice surprise.  Just lots of fiddly 0805 surface mount components to place.

I’ve made a quick video of the project to demonstrate what it can do.

Schematics for the Chipstomp

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Here are the schematics for the Chipstomp.
I’ve tried to keep as much compatibility with the original DP32 circuit but I have removed superfluous elements such as the on-board potentiometer and one of the user leds. I’ve also added an additional tactile button, the OLED and resistor mixed Stereo to Mono input/outputs.
Other than that it’s essentially just a joining of the ChipKit DP32 with the Stomp Shield.
ChipStomp v1 (PDF 90Kb) – Eagle CAD schematic – Zipped (88Kb)

Schematic v1

Chipstomp version 1 schematic PNG (2300×1500px, 80Kb)

Video update on Drum-machine progress

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Here’s a video update on where I am with my Drum-machine project. In the past few months I’ve implemented a fair few new features and sorted out some long standing bugs.
Features;

  • A new menu mode using the joystick to navigate.
  • Added control over the LCD Backlight.
  • Added a simple Reverb mode.
  • New LCD driver code to render graphics to a buffer and squirt it out to the LCD via 9bit SPI.
  • Includes a basic graphics library with some widgets to make creating screens easier.
  • Fixed an odd issue with LED’s flashing out of sequence. I had my MAX6957 ports all out or order.
  • Added RUN LED flashing to every 4th beat.
  • Implemented loading and saving to one of 16 JSON files on the SD card.
  • Added a Tuning mode to allow you to individually set the volume and adjust the playback rate of each instrument/sample.

Drum machine progress : From prototype to version 2

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I’ve not posted in a long time so here’s a quick update on the progress of my drum machine. It’s come a fair way from the initial prototype documented in this post back in July 2012.

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A sneak look at version 2 with a new 32bit PIC and a new larger LCD

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