Software UART

Software implemented UART. More...

Detailed Description

Software implemented UART.

This module provides a software implemented Universal Asynchronous Receiver Transmitter. It is intended to be used in situation where hardware UART is not available. The signatures of the functions are similar to the functions declared in uart.h

Currently sending and receiving is not possible at the same time, so loopback operation is not possible.

Files
file	soft_uart.h
	Software UART port descriptor definition.
file	soft_uart_params.h
	Software UART configuration.

Data Structures
struct	soft_uart_conf_t
	Software UART port descriptor. More...

Macros
#define	SOFT_UART_FLAG_INVERT_TX   0x1
	invert the level of the TX signal
#define	SOFT_UART_FLAG_INVERT_RX   0x2
	invert the level of the RX signal

Typedefs
typedef unsigned	soft_uart_t
	Software UART type definition.

Functions
int	soft_uart_init (soft_uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
	Initialize a given UART device.
int	soft_uart_mode (soft_uart_t uart, uart_data_bits_t data_bits, uart_parity_t parity, uart_stop_bits_t stop_bits)
	Setup parity, data and stop bits for a given UART device.
void	soft_uart_write (soft_uart_t uart, const uint8_t *data, size_t len)
	Write data from the given buffer to the specified UART device.
void	soft_uart_poweron (soft_uart_t uart)
	Power on the given UART device.
void	soft_uart_poweroff (soft_uart_t uart)
	Power off the given UART device.

Macro Definition Documentation

SOFT_UART_FLAG_INVERT_RX

#define SOFT_UART_FLAG_INVERT_RX   0x2

invert the level of the RX signal

Definition at line 48 of file soft_uart.h.

SOFT_UART_FLAG_INVERT_TX

#define SOFT_UART_FLAG_INVERT_TX   0x1

invert the level of the TX signal

Definition at line 43 of file soft_uart.h.

Typedef Documentation

soft_uart_t

typedef unsigned soft_uart_t

Software UART type definition.

Definition at line 66 of file soft_uart.h.

Function Documentation

soft_uart_init()

int soft_uart_init	(	soft_uart_t	uart,
		uint32_t	baudrate,
		uart_rx_cb_t	rx_cb,
		void *	arg
	)

Initialize a given UART device.

The UART device will be initialized with the following configuration:

• 8 data bits
• no parity
• 1 stop bit
• baudrate as given

If no callback parameter is given (rx_cb := NULL), the UART will be initialized in TX only mode.

Parameters

[in]	uart	UART device to initialize
[in]	baudrate	desired symbol rate in baud
[in]	rx_cb	receive callback, executed in interrupt context once for every byte that is received (RX buffer filled), set to NULL for TX only mode
[in]	arg	optional context passed to the callback functions

Returns

UART_OK on success

UART_NODEV on invalid UART device

UART_NOBAUD on inapplicable baudrate

UART_INTERR on other errors

soft_uart_mode()

int soft_uart_mode	(	soft_uart_t	uart,
		uart_data_bits_t	data_bits,
		uart_parity_t	parity,
		uart_stop_bits_t	stop_bits
	)

Setup parity, data and stop bits for a given UART device.

Parameters

[in]	uart	UART device to configure
[in]	data_bits	number of data bits in a UART frame
[in]	parity	parity mode
[in]	stop_bits	number of stop bits in a UART frame

Returns

UART_OK on success

UART_NOMODE on other errors

soft_uart_poweroff()

void soft_uart_poweroff

(

soft_uart_t

uart

)

Power off the given UART device.

Parameters

[in]

uart

the UART device to power off

soft_uart_poweron()

void soft_uart_poweron

(

soft_uart_t

uart

)

Power on the given UART device.

Parameters

[in]

uart

the UART device to power on

soft_uart_write()

void soft_uart_write	(	soft_uart_t	uart,
		const uint8_t *	data,
		size_t	len
	)

Write data from the given buffer to the specified UART device.

This function is blocking, as it will only return after len bytes from the given buffer have been send. The way this data is send is up to the implementation: active waiting, interrupt driven, DMA, etc.

Parameters

[in]	uart	UART device to use for transmission
[in]	data	data buffer to send
[in]	len	number of bytes to send