- The pin, also called pin controller, manages pin resources of system on a chip (SoC) vendors and provides the pin multiplexing function.
The pin module, also called pin controller, manages pin resources of system on a chip (SoC) vendors and provides the pin multiplexing function.
- The pin module defines a set of common methods for managing pins, including:
The module defines a set of common methods for managing pins, including:
- Obtaining or releasing the pin description handle: The kernel compares the pin name passed in with the pin names of each controller in the linked list. If a match is found, a pin description handle is obtained. After the operation on the pin is complete, the pin description handle will be released.
- Obtaining or releasing the pin description handle: The kernel compares the pin name passed in with the pin names of each controller in the linked list. If a match is found, a pin description handle is obtained. After the operation on the pin is complete, the pin description handle will be released.
- Setting or obtaining the pull type of a pin: The pull type can be pull-up, pull-down, or floating.
- Setting or obtaining the pull type of a pin: The pull type can be pull-up, pull-down, or floating.
- Setting or obtaining the pull strength of a pin: You can set the pull strength as required.
- Setting or obtaining the pull strength of a pin: You can set the pull strength as required.
- Setting or obtaining the functions of a pin to implement pin multiplexing
- Setting or obtaining the functions of a pin to implement pin multiplexing
### Basic Concepts<a name="section3"></a>
### Basic Concepts<a name="section3"></a>
Pin, as a software concept, provides APIs for uniformly managing the pins from different SoC vendors, providing the pin multiplexing function, and configuring the electrical features of pins.
Pin, as a software concept, provides APIs for uniformly managing the pins from different SoC vendors, providing the pin multiplexing function, and configuring the electrical features of pins.
>The RTC start time is 1970/01/01 Thursday 00:00:00 \(UTC\). The maximum value of **year** must be set based on the requirements specified in the product manual of the in-use component. You do not need to configure the day of the week.
>The RTC start time is 1970/01/01 Thursday 00:00:00 \(UTC\). The maximum value of **year** must be set based on the requirements specified in the product manual of the in-use component. You do not need to configure the day of the week.
>The RTC start time is 1970/01/01 Thursday 00:00:00 \(UTC\). The maximum value of **year** must be set based on the requirements specified in the product manual of the in-use component. You do not need to configure the day of the week.
>The RTC start time is 1970/01/01 Thursday 00:00:00 \(UTC\). The maximum value of **year** must be set based on the requirements specified in the product manual of the in-use component. You do not need to configure the day of the week.
-Serial Peripheral Interface \(SPI\) is a serial bus specification used for high-speed, full-duplex, and synchronous communication.
Serial Peripheral Interface \(SPI\) is a serial bus specification used for high-speed, full-duplex, and synchronous communication.
-SPI is developed by Motorola. It is commonly used for communication with flash memory, real-time clocks, sensors, and analog-to-digital \(A/D\) converters.
SPI is developed by Motorola. It is commonly used for communication with flash memory, real-time clocks, sensors, and analog-to-digital \(A/D\) converters.
-SPI works in controller/device mode. Generally, there is one SPI controller that controls one or more SPI devices. They are connected via four wires:
SPI works in controller/device mode. Generally, there is one SPI controller that controls one or more SPI devices. They are connected via four wires:
- SCLK: clock signals output from the SPI controller
- SCLK: clock signals output from the SPI controller
- MOSI: data output from the SPI controller and input into an SPI device
- MOSI: data output from the SPI controller and input into an SPI device
- MISO: data output from an SPI device and input into the SPI controller
- MISO: data output from an SPI device and input into the SPI controller
- CS: signals enabled by an SPI device and controlled by the SPI controller
- CS: signals enabled by an SPI device and controlled by the SPI controller
-[Figure 1](#fig89085710359) shows the connection between one SPI controller and two SPI devices \(device A and device B\). In this figure, device A and device B share three pins \(SCLK, MISO, and MOSI\) of the controller. CS0 of device A and CS1 of device B are connected to CS0 and CS1 of the controller, respectively.
[Figure 1](#fig89085710359) shows the connection between one SPI controller and two SPI devices \(device A and device B\). In this figure, device A and device B share three pins \(SCLK, MISO, and MOSI\) of the controller. CS0 of device A and CS1 of device B are connected to CS0 and CS1 of the controller, respectively.
