UART Driver

UART Driver API Reference. More...

Functions list
void	uart_configure_default (uart_config_t *config)
	Configure UART Driver configuration structure.
err_t	uart_open (uart_t *obj, uart_config_t *config)
	Open the UART Driver object.
err_t	uart_set_baud (uart_t *obj, uint32_t baud)
	Set the UART baud rate.
err_t	uart_set_parity (uart_t *obj, uart_parity_t parity)
	Set the UART parity.
err_t	uart_set_stop_bits (uart_t *obj, uart_stop_bits_t stop)
	Set the number of UART stop bits.
err_t	uart_set_data_bits (uart_t *obj, uart_data_bits_t bits)
	Set the number of UART data bits.
void	uart_set_blocking (uart_t *obj, bool blocking)
	Set UART Driver in blocking/non-blocking mode.
err_t	uart_write (uart_t *obj, uint8_t *buffer, size_t size)
	Write data to UART.
err_t	uart_print (uart_t *obj, char *text)
	Print the string to UART.
err_t	uart_println (uart_t *obj, char *text)
	Print the string to UART and append new line.
err_t	uart_read (uart_t *obj, uint8_t *buffer, size_t size)
	Read data from UART.
size_t	uart_bytes_available (uart_t *obj)
	Check number of bytes available to read from UART.
void	uart_clear (uart_t *obj)
	Discard all characters from UART buffers.
err_t	uart_close (uart_t *obj)
	Close UART Driver object.

Function Documentation

uart_bytes_available()

size_t uart_bytes_available

(

uart_t *

obj

)

Check number of bytes available to read from UART.

Parameters

[in]

obj

UART driver object. See uart_t structure definition for detailed explanation.

Returns

Returns the number of bytes that are available for reading.

Example

// UART driver context structure.
static uart_t uart;
 
if ( uart_bytes_available( &uart ) )
{
    // If it enters here, data is available for reading.
}

uart_clear()

void uart_clear

(

uart_t *

obj

)

Discards all characters from the output and input buffer.

Parameters

[in]

obj

UART driver object. See uart_t structure definition for detailed explanation.

Returns

Nothing.

Example

// UART driver context structure.
static uart_t uart;
 
// Clear rx and tx buffers.
uart_clear( &uart );

uart_close()

err_t uart_close

(

uart_t *

obj

)

Closes UART driver object, disables all interrupts, resets pin AF to default values, clears all buffers used by object and disables module clock for lower power consumption.

Parameters

[in,out]

obj

UART driver object. See uart_t structure definition for detailed explanation.

Returns

The function can return one of the values defined by err_t, which is dependant on the architecture and ported low level layer.

Example

// UART driver context structure.
static uart_t uart;
 
// Close the UART module object handler.
if ( UART_SUCCESS == uart_close( &uart ) {
    // no error
} else {
    // Handle the error
}

uart_configure_default()

void uart_configure_default

(

uart_config_t *

config

)

Configures uart_config_t structure to default initialization values. Take into consideration that this is just structure variable initial values setting. Values need to be redefined by user.

Parameters

[in,out]

config

configure UART driver configuration structure. See uart_config_t structure definition for detailed explanation.

Default values:

Function	Default value
Tx pin	0xFFFFFFFF (invalid pin)
Rx pin	0xFFFFFFFF (invalid pin)
Baud rate	115200
Data bits	8 data bits
Parity	no parity
Stop bits	1 stop bit
Tx buffer	cleared
Rx buffer	cleared
Tx ring buffer size	zero
Rx ring buffer size	zero

Returns

Nothing.

Example

// UART driver configuration structure.
static uart_config_t uart_cfg;
 
// Fill structure with default values.
uart_configure_default( &uart_cfg );

uart_open()

err_t uart_open	(	uart_t *	obj,
		uart_config_t *	config )

Opens the UART driver object on selected pins. Allocates memory, pins and ring buffers for specified object. Also, initializes interrupts on the global level.

Parameters

[in,out]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	config	configure UART driver configuration settings. See uart_config_t structure definition for detailed explanation.

Returns

The function can return one of the values defined by err_t, which is dependant on the architecture and ported low level layer.

Precondition

Make sure that configuration structure has been adequately populated beforehand. See uart_configure_default definition for detailed explanation.

Note

It is recommended to check return value for error.

Example

// UART driver context structure.
static uart_t uart;
 
// UART driver configuration structure.
static uart_config_t uart_cfg;
 
// Be careful to have large enough buffers.
static uint8_t uart_rx_buffer[128];
 
// Be careful to have large enough buffers.
static uint8_t uart_tx_buffer[128];
 
// Fill structure with default values.
uart_configure_default( &uart_cfg );
 
// Specify desired UART RX pin.
uart_cfg.rx_pin = MIKROBUS_1_RX;
 
// Specify desired UART TX pin.
uart_cfg.tx_pin = MIKROBUS_1_TX;
 
// Declare buffer size.
uart_cfg.tx_ring_size = sizeof( uart_tx_buffer );
 
// Declare buffer size.
uart_cfg.rx_ring_size = sizeof( uart_rx_buffer );
 
// Initialize appropriate interrupt and allocate resources for UART module.
if ( uart_open( &uart, &uart_cfg ) == UART_ERROR )
{
    // Error handling strategy
}

uart_print()

err_t uart_print	(	uart_t *	obj,
		char *	text )

Print the string pointed to by text.

Parameters

[in]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	text	Pointer to text array.

Returns

Returns the number of bytes that were actually written, or -1 if an error occurred.

Precondition

Make sure that adequate memory has been allocated beforehand, and the module was configured adequately ( bit-rate... ). See uart_open, uart_set_baud, uart_set_data_bits, uart_set_stop_bits and uart_set_parity definition for detailed explanation.

Note

Take into consideration that the function shall return (-1) if no data was written, and appropriate error handling strategy is recommended.

Example

// UART driver context structure.
static uart_t uart;
 
// Number of written bytes.
static size_t size;
 
// Print out "Hello!".
size = uart_print( &uart, "Hello!" );

uart_println()

err_t uart_println	(	uart_t *	obj,
		char *	text )

Print the string pointed to by text and append new line at the end.

Parameters

[in]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	text	Pointer to text array.

Returns

Returns the number of bytes that were actually written, or -1 if an error occurred.

Precondition

Make sure that adequate memory has been allocated beforehand, and the module was configured adequately ( bit-rate... ). See uart_open, uart_set_baud, uart_set_data_bits, uart_set_stop_bits and uart_set_parity definition for detailed explanation.

Note

Take into consideration that the function shall return (-1) if no data was written, and appropriate error handling strategy is recommended.

Example

// UART driver context structure.
static uart_t uart;
 
// Number of written bytes.
static size_t size;
 
// Print out "Hello!" and append new line.
size = uart_print_ln( &uart, "Hello!" );

uart_read()

err_t uart_read	(	uart_t *	obj,
		uint8_t *	buffer,
		size_t	size )

Reads at most size bytes of data from the device into buffer.

Parameters

[in]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[out]	buffer	Array to place read data in.
[in]	size	Number of bytes to be written.

Returns

Returns the number of bytes that were actually read, or -1 if an error occurred.

Precondition

Make sure that adequate memory has been allocated beforehand, and the module was configured adequately ( bit-rate... ). See uart_open, uart_set_baud, uart_set_data_bits, uart_set_stop_bits and uart_set_parity definition for detailed explanation.

Note

Take into consideration that the function shall return (-1) if no data was read, and appropriate error handling strategy is recommended.

Example

// UART driver context structure.
static uart_t uart;
 
// Data receive buffer.
uint8_t *uart_rx_buffer;
 
// Number of read bytes.
static size_t size;
 
// Read data.
size = uart_read( &uart, uart_rx_buffer, sizeof( buffer ) );

uart_set_baud()

err_t uart_set_baud	(	uart_t *	obj,
		uint32_t	baud )

Sets the baud rate to specified baud value.

Parameters

[in]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	baud	Specified baud rate value.

Returns

The function can return one of the values defined by err_t, which is dependant on the architecture and ported low level layer.

Precondition

Make sure that adequate memory has been allocated beforehand. See uart_open definition for detailed explanation.

Note

It is recommended to check return value for error.

Example

// UART driver context structure.
static uart_t uart;
 
// Set baud rate.
if ( uart_set_baud( &uart, 115200 ) == UART_ERROR )
{
    // Error handling strategy
}

uart_set_blocking()

void uart_set_blocking	(	uart_t *	obj,
		bool	blocking )

Sets the UART driver to work in blocking/non-blocking mode.

Parameters

[in,out]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	blocking	true for blocking mode, false for non-blocking mode.

Returns

Nothing.

Example

// UART driver context structure.
static uart_t uart;
 
// Set UART Driver in blocking mode.
uart_set_blocking( &uart, true );

uart_set_data_bits()

err_t uart_set_data_bits	(	uart_t *	obj,
		uart_data_bits_t	bits )

Sets the number of data bits to be used by the UART driver.

Parameters

[in,out]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	bits	Data bits. See uart_data_bits_t for valid values.

Returns

The function can return one of the values defined by err_t, which is dependant on the architecture and ported low level layer.

Precondition

Make sure that adequate memory has been allocated beforehand. See uart_open definition for detailed explanation.

Note

It is recommended to check return value for error.

Example

// UART driver context structure.
static uart_t uart;
 
// Set data bits. ( 8-bit data )
if ( uart_set_data_bits( &uart, UART_DATA_BITS_DEFAULT ) == UART_ERROR )
{
    // Error handling strategy
}

uart_set_parity()

err_t uart_set_parity	(	uart_t *	obj,
		uart_parity_t	parity )

Sets parity scheme to be used by the UART driver.

Parameters

[in,out]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	parity	Parity. See uart_parity_t for valid values.

Returns

The function can return one of the values defined by err_t, which is dependant on the architecture and ported low level layer.

Precondition

Make sure that adequate memory has been allocated beforehand. See uart_open definition for detailed explanation.

Note

It is recommended to check return value for error.

Example

// UART driver context structure.
static uart_t uart;
 
// Set data parity. ( no parity )
if ( uart_set_parity( &uart, UART_PARITY_DEFAULT ) == UART_ERROR )
{
    // Error handling strategy
}

uart_set_stop_bits()

err_t uart_set_stop_bits	(	uart_t *	obj,
		uart_stop_bits_t	stop )

Sets the number of stop bits to be used by the UART driver.

Parameters

[in,out]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	stop	Stop bits. See uart_stop_bits_t for valid values.

Returns

The function can return one of the values defined by err_t, which is dependant on the architecture and ported low level layer.

Precondition

Make sure that adequate memory has been allocated beforehand. See uart_open definition for detailed explanation.

Note

It is recommended to check return value for error.

Example

// UART driver context structure.
static uart_t uart;
 
// Set stop bits. ( one stop bit )
if ( uart_set_stop_bits( &uart, UART_STOP_BITS_DEFAULT ) == UART_ERROR )
{
    // Error handling strategy
}

uart_write()

err_t uart_write	(	uart_t *	obj,
		uint8_t *	buffer,
		size_t	size )

Writes at most size bytes of data from buffer to the device.

Parameters

[in]	obj	UART driver object. See uart_t structure definition for detailed explanation.
[in]	buffer	Array containing data to be written.
[in]	size	Number of bytes to be written.

Returns

Returns the number of bytes that were actually written, or -1 if an error occurred.

Precondition

Make sure that adequate memory has been allocated beforehand, and the module was configured adequately ( bit-rate... ). See uart_open, uart_set_baud, uart_set_data_bits, uart_set_stop_bits and uart_set_parity definition for detailed explanation.

Note

Take into consideration that the function shall return (-1) if no data was written, and appropriate error handling strategy is recommended.

Example

// UART driver context structure.
static uart_t uart;
 
// Data transmit buffer.
uint8_t *uart_tx_buffer;
 
// Number of written bytes.
static size_t size;
 
// Write size number of data from buffer.
size = uart_write( &uart, uart_tx_buffer, size );