make menuconifg中的< > pinctrl-based I2C demultiplexer 介 绍

pinctrl-based I2C demultiplexer是一种基于pinctrl的I2C解复用器，可以将一个I2C总线扩展为多个设备。I2C总线是一种串行通信协议，用于连接微控制器和各种外设（如传感器、存储器、显示器等）。在某些应用中，需要连接多个I2C设备到同一个I2C总线上，但是每个设备的I2C地址必须唯一。此时，可以使用I2C demultiplexer将一个I2C总线扩展为多个设备，并且每个设备都具有唯一的I2C地址。

pinctrl-based I2C demultiplexer使用pinctrl（pin control）技术来控制I2C解复用器的引脚。Pinctrl是一个Linux内核框架，用于控制芯片的引脚分配和配置。通过pinctrl，可以灵活地控制I2C解复用器的引脚，以适应不同的硬件环境。

在Linux内核中，pinctrl-based I2C demultiplexer是通过CONFIG_I2C_MUX_PCA954x选项来启用的。该选项允许用户在内核配置中选择启用pinctrl-based I2C demultiplexer功能，并设置相应的参数。配置完成后，用户可以在设备树中添加I2C demultiplexer节点，并在其中指定解复用器的地址和引脚配置，以便内核在启动时正确地初始化解复用器并将其添加到I2C总线中。

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i2c pca9548

I2C PCA9548 is a multiplexer/demultiplexer IC (Integrated Circuit) that allows multiple I2C devices to share the same I2C bus. It provides a way to expand the number of available I2C addresses and enables communication with multiple devices using a single I2C bus.

The PCA9548 has 8 channels, each of which can be independently controlled to connect or disconnect a specific I2C device from the bus. This allows for efficient management of multiple I2C devices, especially in situations where there are limited I2C addresses available.

To use the PCA9548, you need to communicate with it over the I2C bus using the appropriate I2C commands. By selecting the desired channel, you can control which I2C device is connected to the bus and communicate with it.

Some key features of the PCA9548 include:

1. 8 channels for connecting multiple I2C devices.
2. Individual channel control for enabling/disabling specific devices.
3. Low RDS(on) switches for minimal signal distortion.
4. Supports I2C bus speeds up to 400 kHz.
5. Compatible with both 3.3V and 5V systems.