florian.berthold
f100eb23bf
Schematic includes: - Power section: SS14 reverse protection, AMS1117-3.3 LDO - RP2040-Zero and OLED module headers - Trigger output: 74LVC1G17 Schmitt buffer - Return input: voltage divider, BAT54 clamps, MCP6001 buffer - Button with pull-up, power LED BOM updated with correct parts and LCSC numbers. ASCII schematic reference in hardware/kicad/README.md.
125 lines
7.8 KiB
Markdown
125 lines
7.8 KiB
Markdown
# SN-L00 KiCad Project
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## Schematic Overview
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```
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+12V (from Eurorack)
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│
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▼
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┌─────────────────────────────────────────────────────────────────┐
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│ POWER SECTION │
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│ │
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│ J1 (2x5) D1 (SS14) U1 (AMS1117-3.3) │
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│ Eurorack ──────►Schottky──┬────►LDO────────────► +3.3V │
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│ Header protection │ │ │
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│ C1 C2,C3 │
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│ 10uF 10uF+100nF │
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│ │ │ │
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│ GND GND │
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└─────────────────────────────────────────────────────────────────┘
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┌─────────────────────────────────────────────────────────────────┐
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│ MCU & DISPLAY │
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│ │
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│ MOD1 (RP2040-Zero) MOD2 (OLED 128x32) │
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│ ┌─────────────┐ ┌──────────┐ │
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│ │ 3V3 5V │ │ GND │ │
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│ │ GND GND │ │ VCC │◄── +3.3V │
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│ │ GP0 GP9 │──SDA───────────►│ SDA │ │
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│ │ GP1 GP8 │──SCL───────────►│ SCL │ │
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│ │ GP2 GP7 │──TRIG_OUT └──────────┘ │
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│ │ GP3 GP6 │──RETURN_IN │
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│ │ GP4 GP5 │──BTN │
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│ │ GP29 3V3 │ │
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│ │ GND GND │ │
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│ └─────────────┘ │
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└─────────────────────────────────────────────────────────────────┘
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┌─────────────────────────────────────────────────────────────────┐
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│ TRIGGER OUTPUT │
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│ │
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│ GP2 ────► U2 (74LVC1G17) ────► R3 (100Ω) ────► J2 (TRIG OUT) │
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│ Schmitt buffer current limit 3.5mm jack │
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│ │ │
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│ C4 (100nF) to GND │
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└─────────────────────────────────────────────────────────────────┘
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┌─────────────────────────────────────────────────────────────────┐
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│ RETURN INPUT │
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│ │
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│ J3 (RETURN) ──► R4 (10K) ──┬──► R5/R6 divider ──► U3 ──► GP3 │
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│ 3.5mm jack protection │ (10K/22K = 0.69x) MCP6001 │
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│ │ buffer │
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│ ├── D3 to +3.3V (clamp high) │
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│ └── D4 to GND (clamp low) │
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│ BAT54 Schottky │
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└─────────────────────────────────────────────────────────────────┘
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┌─────────────────────────────────────────────────────────────────┐
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│ BUTTON │
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│ │
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│ +3.3V ──► R1 (10K) ──┬──► GP4 │
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│ pull-up │ │
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│ SW1 ──► GND │
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│ tactile │
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└─────────────────────────────────────────────────────────────────┘
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┌─────────────────────────────────────────────────────────────────┐
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│ POWER LED │
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│ │
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│ +3.3V ──► R2 (1K) ──► D2 (Green LED) ──► GND │
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└─────────────────────────────────────────────────────────────────┘
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```
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## RP2040-Zero Pinout Reference
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```
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┌─────────────────┐
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5V ──┤ 5V 3V3 ├── 3.3V
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GND ──┤ GND GND ├── GND
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GP29 ──┤ GP29 GP0 ├── I2C SDA → OLED
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GP28 ──┤ GP28 GP1 ├── I2C SCL → OLED
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GP27 ──┤ GP27 GP2 ├── TRIG_OUT → 74LVC1G17
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GP26 ──┤ GP26 GP3 ├── RETURN_IN ← MCP6001
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GP15 ──┤ GP15 GP4 ├── BTN (active low)
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GP14 ──┤ GP14 GP5 ├── (spare)
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└─────────────────┘
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USB-C on bottom
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```
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## Files
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- `SN-L00.kicad_pro` - KiCad project file
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- `SN-L00.kicad_sch` - Schematic (open in KiCad 8+)
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- `SN-L00.kicad_pcb` - PCB layout (to be created)
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## Design Notes
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### Power
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- Single +12V rail used (no -12V needed)
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- AMS1117-3.3 LDO provides 3.3V for MCU and peripherals
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- SS14 Schottky for reverse polarity protection
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- Total current draw ~20-30mA
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### Trigger Output
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- 74LVC1G17 provides clean Schmitt-trigger buffered output
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- 100Ω series resistor for short-circuit protection
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- Output: 0-3.3V (compatible with most Eurorack gate inputs)
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### Return Input
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- Handles 0-10V Eurorack signals safely
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- 10K/22K voltage divider scales to ~0-3.1V
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- Schottky clamp diodes protect against overvoltage
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- MCP6001 rail-to-rail op-amp buffers signal
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- Threshold set in firmware (~1.5V default)
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### I2C
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- 400kHz I2C to OLED display
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- No external pull-ups needed (internal to OLED module)
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## Opening the Project
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1. Install KiCad 8.0+
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2. Open `SN-L00.kicad_pro`
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3. Schematic editor opens automatically
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