ER-STIX

Features

• Similar to Mutable Instruments Branches
  • Dual Bernoulli Gate
• Differences vs Branches
  • Only has 1 GATE input
  • No push buttons
  • 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 for OUT 1
• RV4 is mode for OUT 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 - 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
  • 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
  • 2 pots, one for OUT1A/B, other for OUT2A/2B
• Still pretty simple - Version 2
  • 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

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.

Build

• Built on ER-PROTO-02

• 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

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
11	6	RX2, RX7, RX9, RX15, RX17	1K
12	2	RVX1, RVX2	100K
13	2	RX3, RX4	220
14	2	RX11, RX13	100K
7	6	JX1-JX6	Jack