ER-STIX

Features

Similar to Mutable Instruments Branches
- Dual Bernoulli Gate
Differences vs Branches
- Only has 1 GATE input
- No push buttons
  - Uses Pots to control mode - more modes than Branches
- 0-5V input/outputs
Built on ER-PROTO-02
Arduino Pro Mini
Protection on all external jacks with Schottky diode clamps
10-pin Eurorack power
- Uses +12V only

Operation

Receives single Gate on J1
RV1 controls OUT 1
RV2 controls OUT 2
RV3 is mode control 1
RV4 is mode control 2

Arduino Pro Mini

Works with ATMega168 (or 328)
Program from FTDI

Arduino Pins

Controls

RV1 - Probabilistic ratio for Output 1
- Center = 50-50, CCW = Out1A on 100%, CW = 0% on OUT1B
- Inserting J3 jack disables RV1
RV2 - Probabilistic ratio for Output 2
- Center = 50-50, CCW = Out1A on 100%, CW = 0% on OUT1B
- Inserting J3 jack disables RV1
RV3 - OUT 1 Mode
- 7-12 o'clock = Normal Mode drives only OUT1A or OUT1B
- 12-5 o'clock = Drives both OUT1A and OUT1B
RV4 - OUT 2 Mode
- 7-12 o'clock = Normal Mode drives only OU21A or OUT2B
- 12-5 o'clock = Drives both OUT2A and OUT2B

Jacks

J1 - Gate

0.6V threshold GATE input

J2 - OUT1 Random %

0-5V control input
Inserting jack disables RV1
0V = 100% on OUT1A, 2.5V = 50% on OUT1A/OUT1B, 5V = 100% on OUT1B

J3 - Out1A

Gate output 1
0-5V digital output

J4 - Out1B

Gate output 1
0-5V digital output

J5 - Out2A

Gate output 2
0-5V digital output

J6 - Out2B

Gate output 2
0-5V digital output

Schematic

Schematic

Software

Arduino IDE

Pot/GATEs Test

Pot/GATEs Test code GitHub
Used for testing the hardware works
Reads (4) pots and prints values to monitor, write values to serial
Toggles GATE outs - one at a time
Tests RV1/J2 loopback

Simplest Version 1

Simplest Version 1 code GitHub
2 pots, one for OUT1A/B, other for OUT2A/2B

Still pretty simple - Version 2

Still pretty simple - Version 2 code GitHub
Adds (2) mode control knobs
7 o-clock = 12 o'clock = Normal mode
12 o-clock - 5 o=clock = Send Outputs on both OUTxA and OUTxB
Measured GATE in to OUT latency < 20uS using digitalRead and digitalWrite
Improved by accessing the ports directly
- Measured at 2 uS

Sketch uses 1990 bytes (13%) of program storage space. Maximum is 14336 bytes.
Global variables use 13 bytes (1%) of dynamic memory, leaving 1011 bytes for local variables. Maximum is 1024 bytes.

More modes - Version 3

8 modes - Version 3 code GitHub
Modes set by RV3, RV4


RV1 controls p() getting OUT1A vs OUT1B
RV2 controls p() getting OUT2A vs OUT2B
Toss the coin for each output independetly
RV1 controls p() OUT1A and p() OUT1B independently
RV2 controls p() OUT2A and p() OUT2B independently
RV! controls p() of switching to OUT1A > OUT1B, etc
RV2 controls p() of switching to OUT2A > OUT2B, etc
RV1 controls p() of driving OUT1A and OUT1B
RV2 controls p() of driving OUT2A and OUT2B
OUT is randomly selected
RV1 controls p() sending OUTxY
RV2 is not used
RV1 is p() of whether any gate goes out
RV2 us p() or selecting OUT1 vs OUT2
RV!, RV2 control whether to step or not
CW on both stops stepping
CCW always step
RV1 controls p() of driving OUT1A/OUT1B
RV2 controls p() of driving OUT2A/OUT2B

Build

Built on ER-PROTO-02

Build Pictures

Covered RV5, RV6 holes with black duct tape
Labels are White on Black P-Touch labels

Nets

  (nets
    (net (code "1") (name "+5V")
      (node (ref "D3") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "D5") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "J28") (pin "1") (pinfunction "VCC") (pintype "power_in"))
      (node (ref "RVX1") (pin "1") (pinfunction "1") (pintype "passive"))
      (node (ref "RVX2") (pin "1") (pinfunction "1") (pintype "passive"))
      (node (ref "RVX3") (pin "1") (pinfunction "1") (pintype "passive"))
      (node (ref "RVX4") (pin "1") (pinfunction "1") (pintype "passive"))
      (node (ref "U1") (pin "22") (pinfunction "Vcc2") (pintype "unspecified")))
    (net (code "2") (name "+12V")
      (node (ref "C1") (pin "1") (pintype "passive"))
      (node (ref "D1") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "U1") (pin "19") (pinfunction "RAW") (pintype "unspecified")))
    (net (code "3") (name "GATE")
      (node (ref "D2") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "D5") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "J29") (pin "10") (pinfunction "J1_T") (pintype "passive"))
      (node (ref "Q1") (pin "2") (pinfunction "B") (pintype "passive"))
      (node (ref "RX11") (pin "1") (pintype "passive")))
    (net (code "4") (name "GND")
      (node (ref "C1") (pin "2") (pintype "passive"))
      (node (ref "D11") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D13") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D2") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D4") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D7") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D9") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "J28") (pin "20") (pinfunction "GND") (pintype "power_in"))
      (node (ref "J29") (pin "1") (pinfunction "GND") (pintype "power_in"))
      (node (ref "J29") (pin "15") (pinfunction "GND") (pintype "power_in"))
      (node (ref "J29") (pin "16") (pinfunction "GND") (pintype "power_in"))
      (node (ref "J29") (pin "2") (pinfunction "GND") (pintype "power_in"))
      (node (ref "J9") (pin "3") (pinfunction "Pin_3") (pintype "passive"))
      (node (ref "J9") (pin "4") (pinfunction "Pin_4") (pintype "passive"))
      (node (ref "J9") (pin "5") (pinfunction "Pin_5") (pintype "passive"))
      (node (ref "J9") (pin "6") (pinfunction "Pin_6") (pintype "passive"))
      (node (ref "J9") (pin "7") (pinfunction "Pin_7") (pintype "passive"))
      (node (ref "J9") (pin "8") (pinfunction "Pin_8") (pintype "passive"))
      (node (ref "JX1") (pin "S") (pintype "passive"))
      (node (ref "JX2") (pin "S") (pintype "passive"))
      (node (ref "JX3") (pin "S") (pintype "passive"))
      (node (ref "JX4") (pin "S") (pintype "passive"))
      (node (ref "JX5") (pin "S") (pintype "passive"))
      (node (ref "JX6") (pin "S") (pintype "passive"))
      (node (ref "Q1") (pin "1") (pinfunction "E") (pintype "passive"))
      (node (ref "RVX1") (pin "3") (pinfunction "3") (pintype "passive"))
      (node (ref "RVX2") (pin "3") (pinfunction "3") (pintype "passive"))
      (node (ref "RVX3") (pin "3") (pinfunction "3") (pintype "passive"))
      (node (ref "RVX4") (pin "3") (pinfunction "3") (pintype "passive"))
      (node (ref "U1") (pin "10") (pinfunction "GND") (pintype "unspecified"))
      (node (ref "U1") (pin "20") (pinfunction "GND3") (pintype "unspecified")))
    (net (code "5") (name "IN1")
      (node (ref "Q1") (pin "3") (pinfunction "C") (pintype "passive"))
      (node (ref "U1") (pin "12") (pinfunction "D3") (pintype "bidirectional")))
    (net (code "6") (name "LED1A")
      (node (ref "J28") (pin "12") (pinfunction "POT5_2_W") (pintype "passive"))
      (node (ref "LED1") (pin "1") (pinfunction "KA") (pintype "input"))
      (node (ref "U1") (pin "30") (pinfunction "D10") (pintype "bidirectional")))
    (net (code "7") (name "LED1B")
      (node (ref "J28") (pin "11") (pinfunction "POT5_1_CW") (pintype "passive"))
      (node (ref "RX5") (pin "1") (pintype "passive"))
      (node (ref "U1") (pin "18") (pinfunction "D9") (pintype "bidirectional")))
    (net (code "8") (name "LED2A")
      (node (ref "J28") (pin "3") (pinfunction "POT6_2_W") (pintype "passive"))
      (node (ref "LED2") (pin "1") (pinfunction "KA") (pintype "input"))
      (node (ref "U1") (pin "13") (pinfunction "D4") (pintype "bidirectional")))
    (net (code "9") (name "LED2B")
      (node (ref "J28") (pin "2") (pinfunction "POT6_1_CW") (pintype "passive"))
      (node (ref "RX6") (pin "1") (pintype "passive"))
      (node (ref "U1") (pin "14") (pinfunction "D5") (pintype "bidirectional")))
    (net (code "10") (name "MODE1")
      (node (ref "J28") (pin "15") (pinfunction "POT3_2_W") (pintype "passive"))
      (node (ref "RX3") (pin "1") (pintype "passive"))
      (node (ref "U1") (pin "26") (pinfunction "A0") (pintype "bidirectional")))
    (net (code "11") (name "MODE2")
      (node (ref "J28") (pin "6") (pinfunction "POT4_2_W") (pintype "passive"))
      (node (ref "RX4") (pin "1") (pintype "passive"))
      (node (ref "U1") (pin "23") (pinfunction "A3") (pintype "bidirectional")))
    (net (code "12") (name "NORM")
      (node (ref "J29") (pin "9") (pinfunction "J1_R_N") (pintype "passive"))
      (node (ref "RX12") (pin "1") (pintype "passive"))
      (node (ref "U1") (pin "16") (pinfunction "D7") (pintype "bidirectional")))
    (net (code "13") (name "Net-(D1-Pad2)")
      (node (ref "D1") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "R1") (pin "1") (pintype "passive")))
    (net (code "14") (name "Net-(D10-Pad1)")
      (node (ref "D10") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "D12") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "D6") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "D8") (pin "1") (pinfunction "K") (pintype "passive")))
    (net (code "15") (name "Net-(J9-Pad9)")
      (node (ref "J9") (pin "9") (pinfunction "Pin_9") (pintype "passive"))
      (node (ref "R1") (pin "2") (pintype "passive")))
    (net (code "16") (name "Net-(JX1-PadT)")
      (node (ref "JX1") (pin "T") (pintype "passive"))
      (node (ref "RX11") (pin "2") (pintype "passive")))
    (net (code "17") (name "Net-(JX1-PadTN)")
      (node (ref "JX1") (pin "TN") (pintype "passive"))
      (node (ref "RX12") (pin "2") (pintype "passive")))
    (net (code "18") (name "Net-(JX2-PadT)")
      (node (ref "JX2") (pin "T") (pintype "passive"))
      (node (ref "RX13") (pin "2") (pintype "passive")))
    (net (code "19") (name "Net-(JX2-PadTN)")
      (node (ref "JX2") (pin "TN") (pintype "passive"))
      (node (ref "RX14") (pin "2") (pintype "passive")))
    (net (code "20") (name "Net-(JX3-PadT)")
      (node (ref "JX3") (pin "T") (pintype "passive"))
      (node (ref "RX9") (pin "1") (pintype "passive")))
    (net (code "21") (name "Net-(JX4-PadT)")
      (node (ref "JX4") (pin "T") (pintype "passive"))
      (node (ref "RX15") (pin "1") (pintype "passive")))
    (net (code "22") (name "Net-(JX5-PadT)")
      (node (ref "JX5") (pin "T") (pintype "passive"))
      (node (ref "RX7") (pin "1") (pintype "passive")))
    (net (code "23") (name "Net-(JX6-PadT)")
      (node (ref "JX6") (pin "T") (pintype "passive"))
      (node (ref "RX17") (pin "1") (pintype "passive")))
    (net (code "24") (name "Net-(LED1-Pad2)")
      (node (ref "LED1") (pin "2") (pinfunction "AK") (pintype "input"))
      (node (ref "RX5") (pin "2") (pintype "passive")))
    (net (code "25") (name "Net-(LED2-Pad2)")
      (node (ref "LED2") (pin "2") (pinfunction "AK") (pintype "input"))
      (node (ref "RX6") (pin "2") (pintype "passive")))
    (net (code "26") (name "Net-(RVX1-Pad2)")
      (node (ref "RVX1") (pin "2") (pinfunction "2") (pintype "passive"))
      (node (ref "RX14") (pin "1") (pintype "passive")))
    (net (code "27") (name "Net-(RVX2-Pad2)")
      (node (ref "RVX2") (pin "2") (pinfunction "2") (pintype "passive"))
      (node (ref "RX2") (pin "2") (pintype "passive")))
    (net (code "28") (name "Net-(RVX3-Pad2)")
      (node (ref "RVX3") (pin "2") (pinfunction "2") (pintype "passive"))
      (node (ref "RX3") (pin "2") (pintype "passive")))
    (net (code "29") (name "Net-(RVX4-Pad2)")
      (node (ref "RVX4") (pin "2") (pinfunction "2") (pintype "passive"))
      (node (ref "RX4") (pin "2") (pintype "passive")))
    (net (code "30") (name "OUT1A")
      (node (ref "D6") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D7") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "J29") (pin "12") (pinfunction "J3_T") (pintype "passive"))
      (node (ref "RX9") (pin "2") (pintype "passive"))
      (node (ref "U1") (pin "29") (pinfunction "D11") (pintype "bidirectional")))
    (net (code "31") (name "OUT1B")
      (node (ref "D8") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D9") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "J29") (pin "6") (pinfunction "J4_T") (pintype "passive"))
      (node (ref "RX15") (pin "2") (pintype "passive"))
      (node (ref "U1") (pin "17") (pinfunction "D8") (pintype "bidirectional")))
    (net (code "32") (name "OUT2A")
      (node (ref "D10") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D11") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "J29") (pin "14") (pinfunction "J5_T") (pintype "passive"))
      (node (ref "RX7") (pin "2") (pintype "passive"))
      (node (ref "U1") (pin "28") (pinfunction "D12") (pintype "input")))
    (net (code "33") (name "OUT2B")
      (node (ref "D12") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D13") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "J29") (pin "8") (pinfunction "J6_T") (pintype "passive"))
      (node (ref "RX17") (pin "2") (pintype "passive"))
      (node (ref "U1") (pin "15") (pinfunction "D6") (pintype "bidirectional")))
    (net (code "34") (name "R1")
      (node (ref "D3") (pin "2") (pinfunction "A") (pintype "passive"))
      (node (ref "D4") (pin "1") (pinfunction "K") (pintype "passive"))
      (node (ref "J28") (pin "18") (pinfunction "POT1_2_W") (pintype "passive"))
      (node (ref "J29") (pin "4") (pinfunction "J2_T") (pintype "passive"))
      (node (ref "RX13") (pin "1") (pintype "passive"))
      (node (ref "U1") (pin "25") (pinfunction "A1") (pintype "bidirectional")))
    (net (code "35") (name "R2")
      (node (ref "J28") (pin "9") (pinfunction "POT2_2_W") (pintype "passive"))
      (node (ref "RX2") (pin "1") (pintype "passive"))
      (node (ref "U1") (pin "24") (pinfunction "A2") (pintype "bidirectional")))

Parts List

Daughtercard =

Find	Qty	Ref Des	Part Number
1	1	R35	1K
2	1	C1	10uF
3	5	D1-D5	BAT41
4	1	J9	Conn, IDC, Box, 2x5
5	2	LED1, LED2	LED_Dual_2pin
6	1	Q1	2N3904
7	1	R1	10
8	1	U1	ARDUINO PRO MINI

Controls Card

Find	Qty	Ref Des	Part Number
11	8	RX2-4, RX7, RX9, RX15, RX17	1K
12	4	RVX1-RVX4	100K
13	2	RX3, RX4	220
14	2	RX11, RX13	100K
7	6	JX1-JX6	Jack

Mode	RV3	Dependency	RV4	Operation
0	7-12	OUT1/OUT2 independent	7-9	Normal, coin toss output one of OUTxA, OUTxB RV1 controls p() getting OUT1A vs OUT1B RV2 controls p() getting OUT2A vs OUT2B
1	7-12	OUT1/OUT2 independent	9-12	Coin toss determines OUTxA, OUTxB independently Toss the coin for each output independetly RV1 controls p() OUT1A and p() OUT1B independently RV2 controls p() OUT2A and p() OUT2B independently
2	7-12	OUT1/OUT2 independent	12-3	Ping pong A/B RV! controls p() of switching to OUT1A > OUT1B, etc RV2 controls p() of switching to OUT2A > OUT2B, etc
3	7-12	OUT1/OUT2 independent	3-5	Coin toss both on RV1 controls p() of driving OUT1A and OUT1B RV2 controls p() of driving OUT2A and OUT2B
4	12-5	OUT1/OUT2 dependent	7-9	Normal, coin toss one of OUT1A, OUT1B, OUT2A, OUT2B OUT is randomly selected RV1 controls p() sending OUTxY RV2 is not used
5	12-5	OUT1/OUT2 dependent	9-12	Coin toss determines OUTxA, OUTxB dependently, drives both OUTxA/OUTxB RV1 is p() of whether any gate goes out RV2 us p() or selecting OUT1 vs OUT2
6	12-5	OUT1/OUT2 dependent	12-3	Sequential OUT1A, OUT1B, OUT2A, OUT2B RV!, RV2 control whether to step or not CW on both stops stepping CCW always step
7	12-5	OUT1/OUT2 dependent	3-5	All on RV1 controls p() of driving OUT1A/OUT1B RV2 controls p() of driving OUT2A/OUT2B

ER-STIX

Contents

Features

Operation

Arduino Pro Mini

Arduino Pins

Controls

Jacks

J1 - Gate

J2 - OUT1 Random %

J3 - Out1A

J4 - Out1B

J5 - Out2A

J6 - Out2B

Schematic

Software

Pot/GATEs Test

Simplest Version 1

Still pretty simple - Version 2

More modes - Version 3

Build

Build Pictures

Nets

Parts List

Daughtercard =

Controls Card

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