#SMD version of Bastl Kompas

As an attempt to learn kicad I decided to take the open source Bastl Kompas eurorack module, which is a 5hp through-hole soldering project, and redesign it as a 4hp SMD soldering project.

#Bill of Materials

Mouser BOM or find the excel file in this repository.

Parts should come out to be below 20 euros.

#hardware modifications

The SMD version has a different pin mapping which should be described in the code. The reason for this is the following:

#exposing MOSI/MISO/SCK/SS for on-pcb bootloader flashing

With the original Kompas you can take the ATMEGA328 chip, place it on a breadboard, and flash the Arduino bootloader onto it by wiring the MOSI/MISO/SCK/SS pins up to a normal Arduino or another ISP programmer. With the SMD ATMEGA328-AU chip, you can't put it on a breadboard, so the normal way for flashing these with the arduino bootloader

#exposing SDA/SCL pins as extension pins for integration with sensors

This project is based off the ATMEGA328-AU chip, which has 2 additional analog input pins when compared to the ATMEGA328-P that the Bastl Kompas uses.

#different pins

It is easiest to check the code or schematics. This was done to cleanly expose the ICSP headers and serial pins.

#more exposed pins for extensions

#hardware resources

schematic found here

The design was done in Kicad. Also provided are the gerber files for PCB fabrication

#alternative firmwares

See code/ directory.

#window comparator

Essentially an attempt to be half of a Joranalogue 'Compare 2' module. Works alright and the top pot is mapped to a sample rate reduction thing which gives funky results.

#probabilistic latch / burst generator

Dual latch + single burst generator. The latches have probability modulation for likelihood of un/setting.

#CHANGELOG

#rev 3 (untested)

• fixed up some alignments in the panel (I think)
• removed second fuse (reducing parts cost by a 1 euro) because few people would use it

#rev 2

• fixed missing connection issues in rev 1
• ICSP header pins exposed for bootloader flashing
• SDA/SCL serial line pins exposed for interfacing with other components

#rev 1

• direct copy of Bastl version but in SMD.
• has some bugs that require custom connections after.
• flashing arduino bootloader requires soldering jumpers straight to SMD components.

#License

The original (Bastl Kompas)[https://github.com/bastl-instruments/kompas] is CC-BY-SA and this work perpetuates that.

Utmost thanks to the original designers for making their work available!