Ports
| Device | Port | Connected to |
|---|---|---|
| ESP | D0 | NFC: SDA |
| ESP | D1 | MCP: SCK (12) |
| ESP | D2 | MCP: SDA (13) |
| ESP | D3 | --free-- |
| ESP | D4 | --free-- |
| ESP | D5 | SCK |
| ESP | D6 | MISO |
| ESP | D7 | MOSI |
| ESP | D8 | MP3: XCS |
| MCP | B7 | MP3: XRESET |
| MCP | B6 | AMP1: SD |
| MCP | B5 | AMP2: SD |
| MCP | B4 | MP3: XDCS |
| MCP | B3 | MP3: CS |
| MCP | B2 | MP3: DREQ |
| MCP | A0 | BTN_PREV |
| MCP | A1 | BTN_VOL_UP |
| MCP | A2 | BTN_VOL_DOWN |
| MCP | A3 | BTN_NEXT |
Buttons pull to GND if pushed -> Internal Pull-Up needed!