# Firmware Pin Usage

This document summarizes the GPIOs used by the current firmware configuration.
The primary source of truth is `sdkconfig.defaults`; generated `sdkconfig`
differences are called out where they affect runtime behavior. Signal direction
is from the ESP32-S3 MCU perspective.

## Configured Firmware Pins

| GPIO | Signal / Config | Direction | Subsystem | Runtime use | Electrical / logic notes |
| ---: | --- | --- | --- | --- | --- |
| 1 | `CONFIG_MULTIMODAL_AUDIO_I2C_SDA_GPIO` | Bidirectional | Audio codec | ES8311 I2C SDA | I2C port 0, codec control bus |
| 2 | `CONFIG_MULTIMODAL_AUDIO_I2C_SCL_GPIO` | Output | Audio codec | ES8311 I2C SCL | I2C port 0, codec control bus |
| 3 | `CONFIG_TQ_SCREEN_RESET_PIN` | Output | LCD | ST7789 panel reset | Set high after GPIO init; `-1` disables hardware reset |
| 6 | `CONFIG_TQ_SCREEN_SPI_CS_GPIO` | Output | LCD | ST7789 SPI chip select | SPI2 host |
| 7 | `CONFIG_TQ_SCREEN_DC_GPIO` | Output | LCD | ST7789 data/command select | Initialized low |
| 9 | `CONFIG_TQ_SCREEN_BACKLIGHT_GPIO` | Output | LCD | LCD backlight enable | Active-high by default |
| 12 | `CONFIG_MULTIMODAL_AUDIO_PA_GPIO` | Output | Audio amplifier | PA enable / NS4150B control | Managed by codec GPIO interface |
| 13 | `CONFIG_TQ_STEPPER_IN1_GPIO` | Output | Turntable | ULN2003 stepper IN1 | Batched GPIO phase updates |
| 14 | `CONFIG_TQ_STEPPER_IN2_GPIO` | Output | Turntable | ULN2003 stepper IN2 | Batched GPIO phase updates |
| 15 | `CONFIG_MULTIMODAL_PTT_BUTTON_GPIO` | Input | Keys / multimodal | Push-to-talk button K2 | Active-low, internal pull-up enabled |
| 17 | `CONFIG_TQ_SCREEN_SPI_MOSI_GPIO` | Output | LCD | ST7789 SPI MOSI / SDA | SPI2 host |
| 18 | `CONFIG_TQ_SCREEN_SPI_CLK_GPIO` | Output | LCD | ST7789 SPI clock / SCK | SPI2 host, 20 MHz default |
| 21 | `CONFIG_TQ_STEPPER_IN3_GPIO` | Output | Turntable | ULN2003 stepper IN3 | Batched GPIO phase updates |
| 38 | `CONFIG_MULTIMODAL_AUDIO_I2S_MCLK_GPIO` | Output | Audio codec | ES8311 I2S MCLK | Enabled by `CONFIG_MULTIMODAL_AUDIO_USE_MCLK=y` |
| 39 | `CONFIG_MULTIMODAL_AUDIO_I2S_BCLK_GPIO` | Output | Audio codec | ES8311 I2S BCLK / SCLK | I2S port 0 |
| 40 | `CONFIG_MULTIMODAL_AUDIO_I2S_DOUT_GPIO` | Output | Audio codec | MCU PCM output to ES8311 DSDIN | I2S port 0 |
| 41 | `CONFIG_MULTIMODAL_AUDIO_I2S_WS_GPIO` | Output | Audio codec | ES8311 I2S WS / LRCK | I2S port 0 |
| 42 | `CONFIG_MULTIMODAL_AUDIO_I2S_DIN_GPIO` | Input | Audio codec | MCU PCM input from ES8311 ASDOUT | I2S port 0 |
| 45 | `CONFIG_TQ_SLOT_SWITCH_GPIO` | Input | Slot / key input | SW2 slot-machine feature switch | Active-low, internal pull-up enabled |
| 47 | `CONFIG_TQ_STEPPER_IN4_GPIO` | Output | Turntable | ULN2003 stepper IN4 | Batched GPIO phase updates |
| 48 | `CONFIG_TQ_CALIBRATION_SWITCH_GPIO` | Input | Turntable calibration | SW1 direction calibration microswitch | Active-low, internal pull-up enabled |

## Disabled Or Not Connected In Defaults

| Config | Value | Meaning |
| --- | ---: | --- |
| `CONFIG_TQ_SCREEN_SPI_MISO_GPIO` | `-1` | LCD MISO is not connected or not used. |
| `CONFIG_TQ_POWER_HOLD_GPIO` | `-1` | Power-hold output is disabled. |
| `CONFIG_TQ_SLOT_SWITCH_PULLDOWN` | unset | SW2 uses pull-up only. |
| `CONFIG_TQ_CALIBRATION_SWITCH_PULLDOWN` | unset | Calibration switch uses pull-up only. |
| `CONFIG_MULTIMODAL_PTT_BUTTON_PULLDOWN` | unset | PTT button uses pull-up only. |

## Console / Factory CLI

The factory CLI uses `UART_NUM_0` through the ESP-IDF UART driver without
project-specific GPIO remapping. The board reference map routes the debug UART
to the `RXD0` / `TXD0` nets on connector `J2`.

| Interface | Direction | Use |
| --- | --- | --- |
| UART0 RX | Input | Factory CLI input and serial monitor input |
| UART0 TX | Output | ESP log output, factory CLI replies, serial monitor output |

## External Memory Pins

The project enables external PSRAM in octal mode. These are generated ESP-IDF
memory-interface settings in `sdkconfig`, not normal application GPIOs.

| GPIO | Config | Direction | Use | Notes |
| ---: | --- | --- | --- | --- |
| 26 | `CONFIG_SPIRAM_CS_IO` / `CONFIG_DEFAULT_PSRAM_CS_IO` | Memory bus | PSRAM CS | Reserved by ESP32-S3 memory interface |
| 30 | `CONFIG_SPIRAM_CLK_IO` / `CONFIG_DEFAULT_PSRAM_CLK_IO` | Memory bus | PSRAM clock | Reserved by ESP32-S3 memory interface |

Flash pins are controlled by the ESP32-S3 flash interface and are not assigned
by project GPIO configuration.

## Board Nets Present But Not Used By Current Firmware

These nets exist in `docs/gpio-map.md`, but the current firmware does not assign
them to an active project feature.

| GPIO / Net | Board function | Firmware status |
| --- | --- | --- |
| GPIO0 / K1 | Switch to GND, commonly boot/download related | Not consumed by application code |
| GPIO4 | Unassigned | Not used |
| GPIO5 | Unassigned | Not used |
| GPIO8 | Unassigned | Not used |
| GPIO10 / `SWING_PWM` | Swing coil control interface | No current firmware driver/config found |
| GPIO11 | Unassigned | Not used |
| GPIO16 | Unassigned | Not used |
| GPIO35 | Unassigned | Not used |
| GPIO36 | Unassigned | Not used |
| GPIO37 | Unassigned | Not used |
| GPIO46 | Unassigned | Not used |
| GPIO19 / USB D- | USB | Board/system function; not configured by application code |
| GPIO20 / USB D+ | USB | Board/system function; not configured by application code |

## Current Generated `sdkconfig` Difference

`sdkconfig.defaults` enables the key input task:

```text
CONFIG_TQ_KEY_INPUT_ENABLE=y
```

The current generated `sdkconfig` has it disabled:

```text
# CONFIG_TQ_KEY_INPUT_ENABLE is not set
```

This means the defaults describe the intended project pin usage, while the
current generated build configuration may not actively start the interrupt key
input task unless `sdkconfig` is regenerated or updated.

## Source Files

- `sdkconfig.defaults`
- `sdkconfig`
- `main/Kconfig.projbuild`
- `docs/gpio-map.md`
- `components/platform/src/lcd_direct.c`
- `components/platform/src/platform_stepper_driver.c`
- `components/platform/src/multimodal/audio_pipeline/audio_pipeline_codec_impl.c`
- `components/control_plane/src/runtime/control_plane_key_input.c`
- `components/platform/src/platform_console_driver.c`