Calibration Firmware

The firmware tool we use for calibration is available so that DIY builders can test and calibrate their own hardware platform. This guide walks you through the calibration steps:

  1. Testing the LEDs and touch sensors

  2. Testing the IO and trimming the v/oct IO

  3. Measuring the CV offsets

  4. Measuring the signal output offset and storing

1. Testing the LEDs and touch sensors

  1. Connect the module to eurorack power so you can access the back side and maneuver easily. Ensure the -12V rail  (red stripe) on the connector is facing downwards. Start with nothing plugged into the jacks.

  2. If the expander is present, tap the push button to turn the triangle green.

  3. Tap each of the touch sensors; they will successively turn on an LED. After all 6 sensors have been been tested, the LEDs go dark and the module moves on to the next calibration stage.

An LED doesn't work.

A touch sensor doesn't work.

2. Testing the IO and trimming the v/oct IO

  1. All LEDs on the module should be dark.

  2. Turn the black knobs fully clockwise.

  3. Patch the main logic output to the main logic input. You should see the two left white LEDs blink. If that is successful, unpatch from the main logic input and patch into the aux logic input, if the expander is present. You should see the two right LEDs blink.

  4. Test the aux logic input by unpatching from the main logic output, and patch the aux logic output into the aux logic input to verify that output.

  5. Patch either logic input into the CV2 input. The triangle should blink red. 

  6. Patch into the CV3 input and the triangle will blink blue.

  7. Currently, v/oct response is only relevant on the Meta and Sync firmwares, so the next steps are optional if you do not plan to ever use the platform for either of those modules. If you want to skip this step, tap the pushbutton to exit this stage or hold any touch sensor for more than a second.

  8. Patch the output into an audio monitor.  Turn the A and B knobs.  The distance between the A and B manual controls sets the level of the output, and when adjusting, ensure that you can hear a stepped response when adjusting either A or B.  This verifies that the sample and hold circuits are operational. With the knobs furthest apart, you should see a mix of green and red on the bicolor LED. The output is a test tone that can aid v/oct trimming.

  9. The CV1 input is calibrated for v/Oct by means of a trim pot on the analog board. There is a hole in the top left section of the digital board to allow access to the trim pot below. Finding the right screwdriver can be tricky; ideally a trimmer tool such as those from Vishay or Bourns works well and costs a couple of dollars. Get a feel for adjusting the trimmer.  It is somewhat fragile.

  10. Find a sequencer and set the steps so the first half is at a low note and the second half is some number of octaves(volts) above the low note. A bigger octave jump will require a more precise trim but it will be more sensitive. Patch the sequencer CV output into the CV1 input on the module.  Increase the tempo of the sequencer until the output cycles between the high and low voltages about once a second.  You can also manually toggle a reference voltage between two values, with an appropriate span.

  11. Each rising edge is measured, and the color of the triangular LED instructs you how to correct the error. If its blue, adjust the trim pot clockwise (when looking at the module right side up from the back), if its red, turn it to the counterclockwise. When the jump is correct, the triangle is green.

  12. Once you are satisfied with the CV1 response, if you want to use an alternate firmware taking advantage of the signal output v/oct response, patch the signal output into the CV1 input. Use the same method to trim the signal output (the output trim pot is down near the bottom left corner of the analog board). Knob1 sets the speed of the test LFO, knob 2 sets the number of octaves in the jump, and knob3 sets the lower octave.

  13. Once you are satisfied with the trimming, REMOVE ALL PATCH CABLES and press the touch button or hold a touch sensor for more than a second. This advances to the next stage when ADC offsets are calibrated.

Analog A, CV2 and CV3 don't work.

I can't achieve a trim.

3. Measuring the CV offsets

  1. Immediately upon entering this stage, the CV offsets at ground are measured. When measurement is successful, the triangle becomes green.

  2. Patch the signal output into the CV1 output.

  3. You can now press the pushbutton or hold a sensor and release after a second to advance to the final stage where the signal output offset is measured.

4. Measuring the signal output offset and storing

  1. Provided you had the signal output properly patched into the CV1 input, the offset of the signal output was just measured.

  2. You can now press the pushbutton or hold and release a touch sensor for more than a second to store the calibration data. The LEDs will go dark when the data is stored.

  3. Disconnect the module from eurorack power and flash your firmware of choice with the ViaFlash tool.  You must use this tool for uploading firmware if you want to maintain calibration data and presets.