Overview

The Meta Sequencer is a variable length CV step sequencer with a built-in clock divider.

At its core, the Meta Sequencer consists of a step knob and value knob, both which have their own numeric displays. There's also a clock gate input and reset gate input, both with associated pushbuttons. And finally, there's a 12-bit CV output.

An menu system is used for changing settings such as quantization scales, arpeggiations, clock division, sequence length, and randomization.



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Installation

Install the Meta Sequencer as you would any other eurorack module, stripe on the bottom:


The Meta Sequencer does not require a +5 volt source.

Powering Up

When the Meta Sequencer is powered on, the top display will show 'HELO', and the bottom display will show the firmware version number.

Factory Reset

If you'd like to restore your Meta Sequencer to the factory defaults, hold down the RST button while powering on the Meta Sequencer.


Quick Start Guide

Let's get up and running as quickly as possible! The Meta Sequencer ships with a random sequence in memory. Our first goal is to playback this sequence.

Patch the output of the Meta Sequencer into the CV input of an oscillator. Supply a trigger (clock) signal to the Meta Sequencer's CLK input. The meta sequencer requires an external clock souce to function.

Ensure that the mode switch is in the playback position (far left).


You should see the step and value displays changing and hear the pitch change from your VCO.

Modes

The Meta Sequencer has three modes which are selected using the mode switch. They are:

  1. Playback Mode – visualize playback and real-time knob recording
  2. Edit Mode – edit individual steps and values using the STEP and VALUE knobs
  3. Settings Mode – changes settings, such as sequence length and clock division

Saving & Loading

Good news! You don't need to worry about saving or loading anything. The Meta Sequencer remembers everything automatically and instantly. The only value that's not recalled on startup is the sequence playback position. Most other eurorack sequencers start at step 1 when they are first powered on, so we decided to do the same for consistancy sake.


Modes

Playback mode

The Meta Sequencer is in playback mode when the mode switch is in the leftmost position. While in playback mode, the top display will show the step location in the sequence and the bottom display will show the value at that step.

"realtime knob recording": While in playback mode, you may perform "realtime" knob recording by pressing in in the VALUE knob while turning it. You must be clocking the module during realtime recording.

Edit mode

The Meta Sequencer is in edit mode when the mode switch is in the center position. Sequence playback will not be interrupted during editing, but the STEP and VALUE displays will show the note and value are being edited instead of the notes being played.

Editing the sequence is easy:

Important hint: Sequence values range from 0 to 4095. Normally it would be tedious to dial in numbers of this size. However, both knobs have built in switches that can be activated by pushing in on the knob. When adjusting large values, pushing in on a knob while turning it will accellerate the value entry.

Settings mode

The Meta Sequencer has a variety of settings and function. The Meta Sequencer is in settings mode when the mode switch is in the right-most position. The STEP knob is used to select setting or function. The VALUE knob is used to adjust settings or activate functions.

Some functions, such as clear (CLEr) and randomize (rAnd), require you to press in on the VALUE knob to activate the function.

Settings Mode pages:

LEng Sets the pattern length. Ranges from 1 to 64. Default value: 8
cdiv Clock division. Divides the incoming clock signal at CLK. Ranges from 1 to 128. Default value: 1.
SCAL Scale output. Default: none. Quantizes the final output of the module to a musical scale. Scales are:
rAnd Randomize sequence. Press in on the VALUE encoder to randomize the sequence.
CLEr Clear sequence. Press in on the VALUE encoder to clear the current sequence.
SH [[ Shift sequence left one step. The value at the beginning of the sequence is shifted to the end of the sequence.
SH ]] Shift sequence right one step. The value at the end of the sequence is shifted to the beginning of the sequence.
SLiP Slip. Default: 0. This value is a percentage chance (0 to 99) for the sequencer to ignore incoming step inputs. Ignored step inputs will not cause the sequencer's playback position to increment.
Dr-P Drift percentage. Drift settings (percentage and amount) allows the sequence values to drift from their original values. The drift amounts do not affect the underlying sequence and are reset when the sequence is reset. Great for slowly evolving CV output.
Dr-A Drift amount.
hd-o Hold offset. Hold settings (offset and threshold) applies a Sample & Hold to the sequence output based on a gate pattern derived from the hold setting (0-255).
hd-t Hold Threshold
Son1 Sequenced arpeggio pattern select #1
Son2 Sequenced arpeggio pattern select #2
LEdS Brightness setting of the LEDs
rSt Used to reassign rst input as a sample-and-hold input

Settings mode - additional details

Scales

noneNone
MAjoMajor
MinoMinor
ioniIonion
doriDorian
LYdILydian
PHrYPhrygian
MoLYMixolydian
AEOLAeolian
LocrLocrian
MajPMajor Pentatonic
MinPMinor Pentatonic
dimiDiminished
chroChromatic
GAtE"gate" (+0 or +5 volts)

"Hold" settings (hd-o, hd-t)

The Meta Sequencer has a built-in sequenced sample & hold. Setting the Hold Threshold (hd-t) to 0 disables this feature.

A 16 step sequence in the Meta Sequencer might be visualized like so:


As this sequence plays back, if the value output is greater than the Hold Threshold, then that note will be held at the output. If the value is less than the Hold Threshold, then the output won't be updated.

For example, if the Hold Threshold is around 70%, only the following CV values will be held at the output:


This is great, but as the threshold is increased, only the upper-limit of the sequence is output. To offer more variation, the Threshold Offset may be used. When deciding if a value should be held or not, instead of looking at the current step's value, (step + offset)'s value is used. Here we see the same sequence using a Threshhold Offset of "3" and a Threshold of around 70%:

(The arrow illustrates that the first note will be held because the note at step (1+3) has a value over 70%.)


Son1 / Son2 settings

The Meta Sequencer contains 16 transposition sequences. They are:

0) none { 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0 }, 
1) Subtle { 0,0,0,0, 2,2,2,2, 0,0,0,0, 2,2,2,2 }, 
2) Subtle+{ 0,0,0,0, 2,2,2,2, 0,0,0,0, 9,9,9,9 }, 
3) Launch: { 0,0,0,0, 2,2,2,2, 36,36,36,36, 9,9,9,9 }, 
4) Tadeoffs { 24,0,24,0, 12,36,36,2, 29,10,29,10, 9,9,9,9 },
5) Return Home { 0,14,-6,14, 0,-3,-12,14, 0,-5,20,10, 0,12,7,24 },
6) Octaves { 0,0,-12,-12, 12,12,0,0, 0,0,-12,-12, 12,12,0,0 	}, 
7) Down & Up {  0,0,-3,-3, -6,-6,-9,-9, -12,-12,-4,-4, 7,7,10,10 },
8) Fast Acention {  -11,-9,-7,-5, -3,-1,1,3, 5,7,9,11, 13,15,17,19 },
9) Movement {  0,0,0,0, -7,-7,-7,-7, 4,4,4,4, -10,-10,-10,-13 },
10) Extremes {  0,0,-48,-48, 48,48,-36,-36, 36,36,-24,-24, 24,24,-12,-12 },
11) Fairly Random { 0,30,-4,-19, 14,5,-11,24, 22,6,-6,-12, 24,14,-12,2 },
12) Arp up {  0,2,4,2, 4,6,4,6, 8,6,8,9, 8,9,11,8 },
13) Arp up down {  0,4,8,4, 8,12,8,12, 16,12,8,4, 8,4,0,-4 },
14) Wider {  0,1,-1,2,-2,3,-3,4, -4,5,-5,6, -6,7,-7,-8 	},
15) down slide {  9,8,7,6, 5,4,3,2, 1,0,-1,-2, 	-3,-4,-5,-6 },
16) Baby steps {  0,1,2,1, 0,-1,-2,-1, 	0,1,2,1, 0,-1,-2,-1 }
		

Son1 (meaning, "song1") adds one of these arpeggio patterns to the sequence playback. The Son1 arpeggiation patterns are stepped at the same rate as the main sequencer. However, Son2 is stepped at 1/2 rate of the main sequencer. Both Son1 and Son2 can be applied to the output of the main sequence simultaineously.


The Meta Sequencer software is open source, and it's reasonably easy to make modifications to the firmware. Here are instructions to get you started.

What you'll need

  1. Meta Sequencer Firmware - the code.
  2. Arduino IDE - for compiling Meta Sequencer code.
  3. Atmel Studio - for uploading the compiled code to the Meta Sequencer.
  4. Atmel AVRISP MK2 - hardware for connecting your computer to the Meta Sequencer.

Download the code

Once you download the code from github, unzip it into a folder called MetaSequencer. The name of the folder is important. There should be a file called MetaSequencer.ino, along with a number of other .cpp and .h files in the folder.

Preparing the Arduino software

Download and install the Arduino IDE. Double click on the MetaSequencer.ino file that you unzipped in the previous step. The Arduino IDE should open. Set the following settings in the Tools menu:





Turn on detailed compilation messages under File/Preferences:

Compiling the code

Within the Arduino IDE, compile the code using the Sketch / Verify & Compile menu option.

Make a note of the location of the .elf file. This filename will remain constant until you close and reopen the Arduino IDE.

Attaching the programmer to the Meta Sequencer

Upload the code

  1. At this point, power on the Meta Squencer and connect the programmer to your computer via USB.
  2. If you haven't already, install Atmel Studio.
  3. In Atmel Studio, select Tools / Device Programmer. The software should auto-detect the ATmega328 via the ISP interface.
  4. Click "Apply"
  5. Select "Memories" from the menu on the left
  6. In the input labeled Flash, put the path and filename of the .elf file:



  7. Click on "Program".

Overview of the source code

Here are a few of the more important "hackable" files:

Enjoy!!!