Polling UART API

Functions
int	uart_poll_in (const struct device *dev, unsigned char *p_char)
	Read a character from the device for input.
int	uart_poll_in_u16 (const struct device *dev, uint16_t *p_u16)
	Read a 16-bit datum from the device for input.
void	uart_poll_out (const struct device *dev, unsigned char out_char)
	Write a character to the device for output.
void	uart_poll_out_u16 (const struct device *dev, uint16_t out_u16)
	Write a 16-bit datum to the device for output.

Detailed Description

Function Documentation

uart_poll_in()

int uart_poll_in	(	const struct device *	dev,
		unsigned char *	p_char )

#include <zephyr/drivers/uart.h>

Read a character from the device for input.

This routine checks if the receiver has valid data. When the receiver has valid data, it reads a character from the device, stores to the location pointed to by p_char, and returns 0 to the calling thread. It returns -1, otherwise. This function is a non-blocking call.

Parameters

dev	UART device instance.
p_char	Pointer to character.

Return values

0	If a character arrived.
-1	If no character was available to read (i.e. the UART input buffer was empty).
-ENOSYS	If the operation is not implemented.
-EBUSY	If async reception was enabled using uart_rx_enable

uart_poll_in_u16()

int uart_poll_in_u16	(	const struct device *	dev,
		uint16_t *	p_u16 )

#include <zephyr/drivers/uart.h>

Read a 16-bit datum from the device for input.

This routine checks if the receiver has valid data. When the receiver has valid data, it reads a 16-bit datum from the device, stores to the location pointed to by p_u16, and returns 0 to the calling thread. It returns -1, otherwise. This function is a non-blocking call.

Parameters

dev	UART device instance.
p_u16	Pointer to 16-bit data.

Return values

0	If data arrived.
-1	If no data was available to read (i.e., the UART input buffer was empty).
-ENOTSUP	If API is not enabled.
-ENOSYS	If the function is not implemented.
-EBUSY	If async reception was enabled using uart_rx_enable

uart_poll_out()

void uart_poll_out	(	const struct device *	dev,
		unsigned char	out_char )

#include <zephyr/drivers/uart.h>

Write a character to the device for output.

This routine checks if the transmitter is full. When the transmitter is not full, it writes a character to the data register. It waits and blocks the calling thread otherwise. This function is a blocking call. It blocks the calling thread until the character is sent.

To send a character when hardware flow control is enabled, the handshake signal CTS must be asserted.

Parameters

dev	UART device instance.
out_char	Character to send.

uart_poll_out_u16()

void uart_poll_out_u16	(	const struct device *	dev,
		uint16_t	out_u16 )

#include <zephyr/drivers/uart.h>

Write a 16-bit datum to the device for output.

This routine checks if the transmitter is full. When the transmitter is not full, it writes a 16-bit datum to the data register. It waits and blocks the calling thread, otherwise. This function is a blocking call.

To send a datum when hardware flow control is enabled, the handshake signal CTS must be asserted.

Parameters

dev	UART device instance.
out_u16	Wide data to send.