Connectors and controls
- 3.5mm (1/8") mini-jack is a headphone output. Use only for headphones (headphone jack is electrically biased at 1.65V.)
- 6.35mm (1/4") Stereo connector input and output, (labeled on the backside of the circuit board).
- 5 pole DIN connectors are MIDI in- and output (labeled on the backside of the circuit board).
- micro-sd-card (should be FAT formatted)
- micro-usb serves connection for Axoloti software, a power source, and act as a class compliant midi device.
- power input: 2.1mm DC socket, accepts 7-15V DC input, center positive plug. This input will take priority over power from the micro-usb socket.
- full size USB for hosting midi devices 
- 2 LEDs (LED1: green, LED2: red)
- 2 micro push buttons (S1 and S2, also labeled on the bottom side)
By plugging in the micro usb-connection, the board powers up automatically and will run any patch that has been uploaded to run, either from internal flash memory or as a startup patch from sdcard.
The initialisation starts with the two LEDs flashing alternatingly, and then stops with the green LED illuminated.
 currently, only USB class compliant midi devices are supported, see USB Midi Controllers or compatibility. These must be inserted directly into the USB host port. USB hubs are not currently supported on the host port.
Usually the axoloti board will start the patch that has been uploaded to it, as it can run 'standalone'.
If you wish to prevent it start this patch
- power off the board
- hold down S2
- power up the board
Rescue mode (DFU)
there is a special recovery mode, called DFU mode, which can be used to reprogram the board in case the normal flashing procedure fails, this is accessed by.
- power off the board
- hold down switch S1...
- power up the board - no lights will flash
- ...now you can release S1
- go to Axoloti UI, use Flash (Rescue)
Note: you can confirm its in DFU mode, by using Board -> Select Device and you will see its listed as DFU.
Other hardware specifications
- 168 MHz STMF427 microcontroller
- 3.3V signalling voltage on GPIO
- 256kb SRAM (inside the microcontroller)
- 1MB Flash (inside the microcontroller)
- 8MB SDRAM
Audio output limitation
(v1.0 boards only, fixed in v1.1 boards)
from Facebook, regarding audio output, and not using mono plugs:
I have discovered one issue in the board design: plugging a mono jack into the stereo output jack (shorting out the right channel) causes serious distortion in the left (mono) channel.
It was generally agreed there, that this limitation was preferable to causing considerable delays.
Quote from Johannes on topic of power supplies
The DC barrel jack input uses a switching power supply, allowing a wide input voltage range and is capable of powering a USB device connected to the USB host port that consumes 500mA (the legal maximum for USB).
Any supply between 7V and 15V is fine, the current it needs to deliver depends on what you plug into the USB host port. Rough ballpark figures: at 7V, 700mA is fine, at 15V, 250mA is enough. Center pin positive.
DC-plug center diameter should be 2.1 mm.
(there is also a 2.5mm plug variant, will fit too but maybe bad contact, not recommended)
5V on the DC barrel input is not enough. The editor will show you the actual voltage from the switching power supply. That should not be less than 4.75V.
You can also connect a USB cellphone/tablet-style charger to the micro-usb connector.