florian.berthold
c4e1a43dfa
PCB: - 28x100mm 2-layer board outline - Mounting holes for M3 screws - Component placement guide with coordinates - Routing guidelines and design rules Panel: - 6HP (30x128.5mm) Eurorack panel specification - SVG design with hole positions - Supports aluminum, PCB, or acrylic manufacturing Updated main README with full project documentation.
SN-L00 KiCad Project
Schematic Overview
+12V (from Eurorack)
│
▼
┌─────────────────────────────────────────────────────────────────┐
│ POWER SECTION │
│ │
│ J1 (2x5) D1 (SS14) U1 (AMS1117-3.3) │
│ Eurorack ──────►Schottky──┬────►LDO────────────► +3.3V │
│ Header protection │ │ │
│ C1 C2,C3 │
│ 10uF 10uF+100nF │
│ │ │ │
│ GND GND │
└─────────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────┐
│ MCU & DISPLAY │
│ │
│ MOD1 (RP2040-Zero) MOD2 (OLED 128x32) │
│ ┌─────────────┐ ┌──────────┐ │
│ │ 3V3 5V │ │ GND │ │
│ │ GND GND │ │ VCC │◄── +3.3V │
│ │ GP0 GP9 │──SDA───────────►│ SDA │ │
│ │ GP1 GP8 │──SCL───────────►│ SCL │ │
│ │ GP2 GP7 │──TRIG_OUT └──────────┘ │
│ │ GP3 GP6 │──RETURN_IN │
│ │ GP4 GP5 │──BTN │
│ │ GP29 3V3 │ │
│ │ GND GND │ │
│ └─────────────┘ │
└─────────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────┐
│ TRIGGER OUTPUT │
│ │
│ GP2 ────► U2 (74LVC1G17) ────► R3 (100Ω) ────► J2 (TRIG OUT) │
│ Schmitt buffer current limit 3.5mm jack │
│ │ │
│ C4 (100nF) to GND │
└─────────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────┐
│ RETURN INPUT │
│ │
│ J3 (RETURN) ──► R4 (10K) ──┬──► R5/R6 divider ──► U3 ──► GP3 │
│ 3.5mm jack protection │ (10K/22K = 0.69x) MCP6001 │
│ │ buffer │
│ ├── D3 to +3.3V (clamp high) │
│ └── D4 to GND (clamp low) │
│ BAT54 Schottky │
└─────────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────┐
│ BUTTON │
│ │
│ +3.3V ──► R1 (10K) ──┬──► GP4 │
│ pull-up │ │
│ SW1 ──► GND │
│ tactile │
└─────────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────┐
│ POWER LED │
│ │
│ +3.3V ──► R2 (1K) ──► D2 (Green LED) ──► GND │
└─────────────────────────────────────────────────────────────────┘
RP2040-Zero Pinout Reference
┌─────────────────┐
5V ──┤ 5V 3V3 ├── 3.3V
GND ──┤ GND GND ├── GND
GP29 ──┤ GP29 GP0 ├── I2C SDA → OLED
GP28 ──┤ GP28 GP1 ├── I2C SCL → OLED
GP27 ──┤ GP27 GP2 ├── TRIG_OUT → 74LVC1G17
GP26 ──┤ GP26 GP3 ├── RETURN_IN ← MCP6001
GP15 ──┤ GP15 GP4 ├── BTN (active low)
GP14 ──┤ GP14 GP5 ├── (spare)
└─────────────────┘
USB-C on bottom
Files
SN-L00.kicad_pro- KiCad project fileSN-L00.kicad_sch- Schematic (open in KiCad 8+)SN-L00.kicad_pcb- PCB layout (to be created)
Design Notes
Power
- Single +12V rail used (no -12V needed)
- AMS1117-3.3 LDO provides 3.3V for MCU and peripherals
- SS14 Schottky for reverse polarity protection
- Total current draw ~20-30mA
Trigger Output
- 74LVC1G17 provides clean Schmitt-trigger buffered output
- 100Ω series resistor for short-circuit protection
- Output: 0-3.3V (compatible with most Eurorack gate inputs)
Return Input
- Handles 0-10V Eurorack signals safely
- 10K/22K voltage divider scales to ~0-3.1V
- Schottky clamp diodes protect against overvoltage
- MCP6001 rail-to-rail op-amp buffers signal
- Threshold set in firmware (~1.5V default)
I2C
- 400kHz I2C to OLED display
- No external pull-ups needed (internal to OLED module)
Opening the Project
- Install KiCad 8.0+
- Open
SN-L00.kicad_pro - Schematic editor opens automatically