Greenface Labs THE SPANKULATOR User manual

THE SPANKULATOR
USER MANUAL
Greenface Labs -- 2021

TABLE OF CONTENTS
Quick Start .................................................................................................................................3
Overview ................................................................................................................................... 4
Features..............................................................................................................................................4
Signals ................................................................................................................................................4
Operation .................................................................................................................................. 6
General Operation ..............................................................................................................................6
Open Source Project ........................................................................................................................... 7
Trigger ................................................................................................................................................ 7
Repeat Mode....................................................................................................................................... 7
CV Scale..............................................................................................................................................8
Sig In...................................................................................................................................................8
Screen Saver .......................................................................................................................................8
Function Details......................................................................................................................... 9
Up ..................................................................................................................................................... 10
Down ................................................................................................................................................ 11
Stretch.............................................................................................................................................. 12
Toggle............................................................................................................................................... 13
Maytag.............................................................................................................................................. 14
LFO................................................................................................................................................... 15
User .................................................................................................................................................. 16
Bounce...............................................................................................................................................17
WiFi................................................................................................................................................... 18
Terminal Mode..................................................................................................................................20
Settings.............................................................................................................................................22

QUICK START
The Spankulator can be used in an endless variety of ways, but here is a great way to start
exploring. These instructions are for use with a Moog Mother-32 but can be easily adapted to
most modular synthesizers.
MOTHER-32 SET-UP
•VCA Mode –EG (use the envelope generator)
•VCO Mod Amount –Zero
•VCF Mode –Low Pass
•VCF Mod Source –EG
•VCF Mod Amount –0%
•Cutoff –200Hz
•Resonance –50%
•Attack –5%
•Decay 10%
•Sustain –Off
•Frequency –50%
•Pulse Width –50%
•VCO Wave - Pulse
•Octave –4
•Note –8
SPANKULATOR SET-UP
•Fxn –Down (use default parameters as shown in images below)
•Start Pulse Len –100
•End Pulse Len –10
•Num Pulses –10
•Randomness –0
•Initial Delay 100
•Repeat –On
•CV Scale –50%
Connect the Spankulator Trig Out to the M-32 Gate Input, Tog Out to the M-32 VCF Cutoff
Input and CV Out to the M-32 VCO Lin Input. Press Trigger on the Spankulator and you should
hear a sound much like that found here.

OVERVIEW
The Spankulator is a WiFi-enabled multi-function Eurorack module. Its main function is to
generate a trio of coordinated analog and digital signals called Spanks which can be used in an
endless variety of ways; some examples being a sequencer, an envelope generator, or a
complex rhythm generator.
FUNCTIONS
•5 Spank types –Up, Down, Stretch, Toggle and Maytag
•LFO with 3 waveforms –Sine, Ramp Up, Ramp Down
•Bounce –A DVM plus a scalable sample and hold. DC and AC modes
•User Mode –For sending sequences of Spanks and/or LFO bursts
•Settings –For configuration, factory reset, etc.
FEATURES
•128x64 graphic display enhances usability
•WiFi and Terminal interfaces provide even richer user experiences with the addition of
computer resources like a keyboard, display and scripting.
•All settings are stored in Flash memory so that they are retained when power is off
•Selectable Single Shot or Repeat mode
•External Clock mode
•Inputs and Outputs are protected against damage during typical use
SIGNALS
•Gate Out –Digital signal that consists of pulses of varying width.
•Tog Out –Digital signal that toggles with the completion of every Spank.
•CV Out –Analog signal (+/- 5 volt) that depends on the Spank type. Usually, it is relative
to the pulse width of the Gate Output. This signal’s amplitude is adjusted using the CV
Scale control.
•Trigger In –Digital input. Operation is triggered with a 0 to 5 volt transition on this
input. This also serves as the External Clock when Ext Clk mode is enabled.
•Sig In –Analog signal input. Range: +/- 5 volt
(see figure next page)

Figure 1 - Front Panel

OPERATION
GENERAL OPERATION
(Please see the Terminal and Web Interface sections for more details)
•The Function is selected using the +and –buttons.
oTerminal uses the +and –keys.
oWeb Interface has dedicated Function buttons.
oEach function has one or more parameters.
•Parameters are adjusted using the arrow keys and the Adjust knob.
oParameters are selected using the up and down arrows.
oDigit to be adjusted is selected by using the right and left arrows.
oUse the Adjust knob to increment and decrement the selected digit.
oParameter values may be directly entered using the Terminal or Web Interface.
•Operation of each function is triggered by a variety of methods.
oPressing the Adjust button.
oReceiving a low to high transition on the Trig In jack.
oTerminal uses the !key to trigger.
oWeb Interface has a dedicated Trigger button.
•Trigger may be single-shot or repetitive.
oPress the Repeat button to toggle the Repeat mode.
oTerminal uses the *key to toggle Repeat mode.
oWeb Interface has a dedicated Repeat button.
•CV Out amplitude can be adjusted from 0 to 100% by a variety of methods.
oUse the CV Scale potentiometer.
oTerminal uses the Okey plus up to three digits ranging from 0 to 1023. (Use the
zkey to refresh the screen after setting this parameter to see the result.)
oWeb Interface has a dedicated Slider control.

OPEN SOURCE PROJECT
The Spankulator is an Open Source project that has an Arduino 33 IoT at its core. The code is
written in C++ and makes use of several public domain code libraries for managing the various
purchased hardware components such as the display and the FRAM non-volatile memory.
Because it is Open Source, in addition to being used by musicians and sound designers to
create new and amazing sounds, the Spankulator can be used by students and entrepreneurs
to create new, amazing modules. And, of course, the open source community will generally
improve the product as times goes along. Links to the design repositories can be found on the
Spankulator web page.
TRIGGER
The Spankulator is controlled by the user issuing Commands. Commands are initiated by
pressing the front panel buttons or by using the WiFi or Terminal interfaces. Regardless of the
source of the command, it will be called either a command or a keypress in this document.
The various functions that the Spankulator performs are called “Spanks”and will be referred to
as such in this document.
All of the Spankulator’s functions are activated by a trigger. Triggers can come from various
sources:
•Pushing the Trigger (Adjust) knob.
•Receiving a 0 to 5V transition on the Trig In jack.
•Receiving a Trigger command from either the Wifi or Terminal interface
When a Trigger is received, the Spankulator will execute a Spank that sends pulses at the Trig
Out jack and varying voltage levels at the CV Out jack. When the Spank ends, the Tog Out jack
will switch polarity from one to zero or vice versa.
REPEAT MODE
If Repeat is set to OFF, the Spankulator will remain in whatever condition it was in when the
Spank ended until it receives another Trigger.
If Repeat is set to ON, the Spank will continuously repeat.
In either case, receipt of another Trigger or Command will interrupt the Spank, stopping
execution until a new Trigger is received.

The Trigger Indicator will be activated when a trigger is received and will be turned off when
the trigger ends. The Trigger Indicator is a Red LED on the front panel and is a widget in the
Web Interface. It is textually indicated on the Status line in Terminal mode.
CV SCALE
The CV Out signal ranges from -5V to +5V. It can be attenuated using the CV Scale control.
When using this control, the CV Out signal will still be centered at zero volts, but it will swing to
a lesser degree depending on the Scale setting.
WiFi mode has a dedicated slider control for CV Scale, and Terminal mode uses the O key
followed by a number from 0 to 1023 followed by a carriage return. Press the screen refresh
command to see the effect.
SIG IN
The Signal In jack has a range of -5V to +5V. It is used by the Bounce function. Signals at this
input currently have no effect in other functions.
This signal is split into two parts, one AC coupled, and the other DC coupled. These signals are
then scaled and biased to the 0 to 3.3V signal that the Arduino requires. More details about the
Bounce function can be found later in this document.
SCREEN SAVER
In order to maximize display life, the display will turn off after a set time. The default time is 15
minutes. The time can be set in the Settings function with a range of 1 to 9999 minutes.
Press any button or push the Trigger knob to bring the display back.

FUNCTION DETAILS
The Spankulator has ten functions. These are listed below with their associated command
index. Details for each function follow.
0. Up
1. Down
2. Stretch
3. Toggle
4. Maytag
5. LFO
6. User
7. Bounce
8. WiFi
9. Settings

UP
Up Spanks send a sequence of pulses that increase in width to Trig Out.
The voltage level at CV Out is proportional to the current pulse width plus or minus a value that
is calculated from the Randomness parameter. The voltage will be at the minimum (-5V) when
the Spank starts and will increase to the maximum (+5V) when the Spank completes. This
range can be reduced by using the CV Scale control.
Parameter
Min
Max
Default
End Pulse Len
10
9999
100
Start Pulse Len
10
9999
10
Num Pulses
2
99
10
Randomness
0
99
0
Initial Delay
0
9999
100
The figure below illustrates an Up Spank with the default settings. The yellow trace is Trig Out
and the purple trace is CV Out.
Figure 2 - Default Up Spank