ESP32S3: PCNT: add support for all counting units

[Hallootto1100]

ESP32: PCNT: add support for all counting units

Overview

The ESP32-S3 features a PCNT (Pulse Counter) peripheral containing 4 independent units, each with two channels, making it capable of interfacing with up to 4 quadrature encoders simultaneously.

Current Status

I successfully configured the first unit and tested it with the qdec sample. While it's possible to define additional units in the device tree, no new device instances are created. Examining the current driver implementation reveals that it hardcodes channel 0, effectively limiting functionality to a single unit.

Additionally, the driver implements SENSOR_CHAN_ROTATION through the sensor API without performing any unit conversion to degrees, simply returning raw counter values.

Root Cause

The fundamental limitation stems from the traditional sensor API's inability to support multiple channels of the same type within a single device. However, Zephyr's new Read and Decode API addresses this constraint by:

• Supporting multiple channels of identical types per device
• Implementing a decoder mechanism that enables two-stage data processing
• Providing flexibility to access either raw values or decoded measurements (angles, distances, etc.)

Although the Read and Decode API remains experimental, it's actively developed and approaching stability.

Proposed Solution:

Develop a new PCNT driver implementation that leverages the Read and Decode API's capabilities. The driver selection could be controlled via CONFIG_SENSOR_ASYNC_API, allowing users to choose between the legacy implementation (single unit) and the new multi-unit capable driver based on their requirements.

This approach would unlock the ESP32-S3 PCNT peripheral's full potential while maintaining backward compatibility with existing applications.

[Hallootto1100]

@sylvioalves could you have a look?