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

Schematics

• 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.

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