CeeS firmware update

Current firmwares:

4.11.2025
CeeS version 1.02 for CS10 and CS15

This guide describes how to update the CeeS firmware.

What you need:

  • MIDI connection from a PC / MAC output to the Cees MIDI input
  • (optional) MIDI Connected from CeeS MIDI out to the PC / MAC
  • A browser supporting WebMIDI (for example Edge, Chrome)

For now, this is using the uniMatrix updater, we will build a dedicated updater eventually.

  1. Open the uniMatrix updater and go to the FIRMWARE UPDATE tap. Make sure to do this in a Browser that supports WebMIDI
  2. Select the correct MIDI output that is connected to CeeS
  3. Load the firmware file by clicking Choose File
  4. Select the ‘ Use recovery mode‘ checkbox

Next, we need to go into the bootloader.

  1. Turn off the CSxx synth
  2. Press and hold down the following Chord: D, F, F#. For CS10/15, this chord must be played at the second keyboard octave
  3. (optional) You can check if you are sucessfully in the bootloader by monitoring the MIDI output, for example with a program like MIDIOX. When entering the bootloader, it will send the sysex string F0 74 74 62 6F 6F 74 F7 once.

Finally, you can update the firmware

  1. Press the ‘Start firmware update’ button.
  2. Wait until your interface stops sending. (The progress bar in the updater is not yet working. This takes about 30 seconds
  3. After a sucessful update, the new firmware will load

You can check the firmware version manually like so:

  1. Send the sysex string: F0 00 74 74 43 65 65 53 09 F7
  2. CeeS will return the string F0 00 74 74 43 65 65 53 09 XX XX F7
  3. The XX XX encodes the version, for example 1.02 would be 01 02