# Peripherals

[中文]

## Touch Sensor

The touch sensor driver has been redesigned into Capacitive Touch Sensor.

- The new driver is in `esp_driver_touch_sens` component and the include path is `driver/touch_sens.h`.

- The legacy driver is still available in the previous include path `driver/touch_sensor.h`.

Although it is recommended to use the new driver APIs, the legacy driver is still available in the previous include path `driver/touch_sensor.h`. However, by default, including `driver/touch_sensor.h` triggers the build warning below. The warning can be suppressed by the Kconfig option CONFIG_TOUCH_SUPPRESS_DEPRECATE_WARN.

The major changes are listed as follows:

### Major Changes

- Now the touch sensor APIs based on different hardware version are integrated into one API set. And each sub-feature is configurable via its own individual API.

- Almost all hardware configurations are public to provide enough flexibility, meanwhile the driver also offers some default configurations to save your time on figuring out a basic workable configuration.

- The new touch driver implemented Finite-State Machine (FSM) to ensure a correct touch sensor operation. Please refer to the programming guide Capacitive Touch Sensor for more details.

- All new APIs are guaranteed to be thread-safe.

- Implemented a software filter for the touch sensor V1 (ESP32), and open for customization.

## Two-Wire Automotive Interface (TWAI)

TWAI provides a brand-new driver interface that supports a wider range of convenient features. Please refer to the programming guide: Two-Wire Automotive Interface (TWAI).

Compared to the legacy driver, the new driver offers several major improvements:

- Event-driven architecture, supporting registration of multiple callback functions

- Runtime configuration changes for bitrate and filter settings

- More intuitive and user-friendly APIs for bitrate and filter configuration

- Support for ESP32-C5 and its FD (Flexible Datarate) capabilities

- Support using multiple TWAI controllers simultaneously

The new driver is located in the esp_driver_twai component. To use it, simply add the component dependency. The relevant header files are esp_driver_twai/include/esp_twai.h and esp_driver_twai/include/esp_twai_onchip.h.

Deprecated/Removed | Replacement | Notes
--- | --- | ---
twai_read_alerts | None | Use `on_state_change` and `on_error` callbacks to receive status and error notifications.
twai_receive | twai_node_receive_from_isr | Can only be called inside the on_rx_done callback.
twai_clear_transmit_queue | None | Not supported at the moment.
twai_clear_receive_queue | None | The new driver uses event-driven receive; blocking receive APIs are not currently provided.

Although we recommend using the new TWAI driver APIs, the legacy driver is still available. To use the legacy driver, include the header file `driver/twai.h`. When using the legacy driver, please note the following:

- The new and legacy drivers are not compatible and must not be used together. Mixing them will trigger warnings during startup, and may even cause crashes and system reboots. To suppress this compatibility check, you may enable the configuration option CONFIG_TWAI_SKIP_LEGACY_CONFLICT_CHECK.

- The legacy driver will no longer receive new features, such as TWAI FD (Flexible Data-rate) support.

## SPI Flash Driver

- New argument `flags` is added to `esp_flash_os_functions_t::start`. Caller and implementer should handle this argument properly.

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