USART FreeRTOS Driver

Overview

Files
file	fsl_usart_freertos.h

Data Structures
struct	rtos_usart_config
	FLEX USART configuration structure. More...
struct	usart_rtos_handle_t
	FLEX USART FreeRTOS handle. More...

USART RTOS Operation
int	USART_RTOS_Init (usart_rtos_handle_t *handle, usart_handle_t *t_handle, const struct rtos_usart_config *cfg)
	Initializes a USART instance for operation in RTOS. More...
int	USART_RTOS_Deinit (usart_rtos_handle_t *handle)
	Deinitializes a USART instance for operation. More...

USART transactional Operation
int	USART_RTOS_Send (usart_rtos_handle_t *handle, const uint8_t *buffer, uint32_t length)
	Sends data in the background. More...
int	USART_RTOS_Receive (usart_rtos_handle_t *handle, uint8_t *buffer, uint32_t length, size_t *received)
	Receives data. More...

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Data Structure Documentation

struct rtos_usart_config

Data Fields
USART_Type *	base
	USART base address.
uint32_t	srcclk
	USART source clock in Hz.
uint32_t	baudrate
	Desired communication speed.
usart_parity_mode_t	parity
	Parity setting.
usart_stop_bit_count_t	stopbits
	Number of stop bits to use.
uint8_t *	buffer
	Buffer for background reception.
uint32_t	buffer_size
	Size of buffer for background reception.

struct usart_rtos_handle_t

Data Fields
USART_Type *	base
	USART base address.
usart_transfer_t	txTransfer
	TX transfer structure.
usart_transfer_t	rxTransfer
	RX transfer structure.
SemaphoreHandle_t	rxSemaphore
	RX semaphore for resource sharing.
SemaphoreHandle_t	txSemaphore
	TX semaphore for resource sharing.
EventGroupHandle_t	rxEvent
	RX completion event.
EventGroupHandle_t	txEvent
	TX completion event.
void *	t_state
	Transactional state of the underlying driver.

Function Documentation

int USART_RTOS_Init	(	usart_rtos_handle_t *	handle,
		usart_handle_t *	t_handle,
		const struct rtos_usart_config *	cfg
	)

Parameters

handle	The RTOS USART handle, the pointer to allocated space for RTOS context.
t_handle	The pointer to allocated space where to store transactional layer internal state.
cfg	The pointer to the parameters required to configure the USART after initialization.

Returns

0 succeed, others fail.

int USART_RTOS_Deinit

(

usart_rtos_handle_t *

handle

)

This function deinitializes the USART module, sets all register values to reset value, and releases the resources.

Parameters

handle

The RTOS USART handle.

int USART_RTOS_Send	(	usart_rtos_handle_t *	handle,
		const uint8_t *	buffer,
		uint32_t	length
	)

This function sends data. It is a synchronous API. If the hardware buffer is full, the task is in the blocked state.

Parameters

handle	The RTOS USART handle.
buffer	The pointer to buffer to send.
length	The number of bytes to send.

int USART_RTOS_Receive	(	usart_rtos_handle_t *	handle,
		uint8_t *	buffer,
		uint32_t	length,
		size_t *	received
	)

This function receives data from USART. It is a synchronous API. If data is immediately available, it is returned immediately and the number of bytes received.

Parameters

handle	The RTOS USART handle.
buffer	The pointer to buffer where to write received data.
length	The number of bytes to receive.
received	The pointer to a variable of size_t where the number of received data is filled.