The Universal Asynchronous Receiver Transmitter features a two-pin UART that can be used for communication and trace purposes and offers an ideal medium for in-situ programming solutions.

Moreover, the association with two peripheral DMA controller (PDC) channels permits packet handling for these tasks with processor time reduced to a minimum.

Usage

Enable the UART peripheral clock in the PMC.
Enable the required UART PIOs (see pio.h).
Configure the UART by calling uart_init.
Send data through the UART using the uart_write.
Receive data from the UART using the uart_read; the availability of data can be polled with uart_is_rx_ready.
Disable the transmitter and/or the receiver of the UART with uart_disable_tx and uart_disable_rx.

Functions
void	uart_config_optical_interface (Uart p_uart, struct uart_config_optical cfg)
	Enable UART optical interface. More...

void	uart_disable (Uart *p_uart)
	Disable UART receiver and transmitter. More...

void	uart_disable_interrupt (Uart *p_uart, uint32_t ul_sources)
	Disable UART interrupts. More...

void	uart_disable_optical_interface (Uart *p_uart)
	Disable UART optical interface. More...

void	uart_disable_rx (Uart *p_uart)
	Disable UART receiver. More...

void	uart_disable_tx (Uart *p_uart)
	Disable UART transmitter. More...

void	uart_enable (Uart *p_uart)
	Enable UART receiver and transmitter. More...

void	uart_enable_interrupt (Uart *p_uart, uint32_t ul_sources)
	Enable UART interrupts. More...

void	uart_enable_optical_interface (Uart *p_uart)
	Enable UART optical interface. More...

void	uart_enable_rx (Uart *p_uart)
	Enable UART receiver. More...

void	uart_enable_tx (Uart *p_uart)
	Enable UART transmitter. More...

uint32_t	uart_get_interrupt_mask (Uart *p_uart)
	Read UART interrupt mask. More...

Pdc *	uart_get_pdc_base (Uart *p_uart)
	Get UART PDC base address. More...

uint32_t	uart_get_status (Uart *p_uart)
	Get current status. More...

uint32_t	uart_init (Uart p_uart, const sam_uart_opt_t p_uart_opt)
	Configure UART with the specified parameters. More...

uint32_t	uart_is_rx_buf_end (Uart *p_uart)
	Check if one receive buffer is filled. More...

uint32_t	uart_is_rx_buf_full (Uart *p_uart)
	Check if both receive buffers are full. More...

uint32_t	uart_is_rx_ready (Uart *p_uart)
	Check if Received data is ready. More...

uint32_t	uart_is_tx_buf_empty (Uart *p_uart)
	Check if both transmit buffers are sent out. More...

uint32_t	uart_is_tx_buf_end (Uart *p_uart)
	Check if one transmit buffer is sent out. More...

uint32_t	uart_is_tx_empty (Uart *p_uart)
	Check if Transmit Hold Register is empty. More...

uint32_t	uart_is_tx_ready (Uart *p_uart)
	Check if Transmit is Ready. More...

uint32_t	uart_read (Uart p_uart, uint8_t puc_data)
	Read from UART Receive Holding Register. More...

void	uart_reset (Uart *p_uart)
	Reset UART receiver and transmitter. More...

void	uart_reset_rx (Uart *p_uart)
	Reset UART receiver. More...

void	uart_reset_status (Uart *p_uart)
	Reset status bits. More...

void	uart_reset_tx (Uart *p_uart)
	Reset UART transmitter. More...

void	uart_set_clock_divisor (Uart *p_uart, uint16_t us_divisor)
	Set UART clock divisor value. More...

void	uart_set_sleepwalking (Uart *p_uart, uint8_t ul_low_value, bool cmpmode, bool cmppar, uint8_t ul_high_value)
	Set sleepwalking match mode. More...

void	uart_set_write_protection (Uart *p_uart, bool flag)
	Enables/Disables write protection mode. More...

uint32_t	uart_write (Uart *p_uart, const uint8_t uc_data)
	Write to UART Transmit Holding Register Before writing user should check if tx is ready (or empty). More...

void uart_config_optical_interface	(	Uart *	p_uart,
		struct uart_config_optical *	cfg
	)

Enable UART optical interface.

Parameters

p_uart	Pointer to a UART instance.
cfg	Pointer to a UART optical interface configuration.

References Assert, uart_config_optical::clk_div, uart_config_optical::duty, uart_config_optical::rx_filter, uart_config_optical::rx_inverted, uart_config_optical::threshold, and uart_config_optical::tx_inverted.

void uart_disable ( Uart * p_uart )

Disable UART receiver and transmitter.

Parameters

p_uart Pointer to a UART instance.

void uart_disable_interrupt	(	Uart *	p_uart,
		uint32_t	ul_sources
	)

Disable UART interrupts.

Parameters

p_uart	Pointer to a UART instance.
ul_sources	Interrupts to be disabled.

void uart_disable_optical_interface ( Uart * p_uart )

Disable UART optical interface.

Parameters

p_uart Pointer to a UART instance.

References Assert.

void uart_disable_rx ( Uart * p_uart )

Disable UART receiver.

Parameters

p_uart Pointer to a UART instance.

void uart_disable_tx ( Uart * p_uart )

Disable UART transmitter.

Parameters

p_uart Pointer to a UART instance.

void uart_enable ( Uart * p_uart )

Enable UART receiver and transmitter.

Parameters

p_uart Pointer to a UART instance.

void uart_enable_interrupt	(	Uart *	p_uart,
		uint32_t	ul_sources
	)

Enable UART interrupts.

Parameters

p_uart	Pointer to a UART instance.
ul_sources	Interrupts to be enabled.

void uart_enable_optical_interface ( Uart * p_uart )

Enable UART optical interface.

Parameters

p_uart Pointer to a UART instance.

References Assert.

void uart_enable_rx ( Uart * p_uart )

Enable UART receiver.

Parameters

p_uart Pointer to a UART instance.

void uart_enable_tx ( Uart * p_uart )

Enable UART transmitter.

Parameters

p_uart Pointer to a UART instance.

uint32_t uart_get_interrupt_mask ( Uart * p_uart )

Read UART interrupt mask.

Parameters

p_uart Pointer to a UART instance.

Returns: The interrupt mask value.

Pdc* uart_get_pdc_base ( Uart * p_uart )

Get UART PDC base address.

Parameters

p_uart Pointer to a UART instance.

Returns: UART PDC registers base for PDC driver to access.

uint32_t uart_get_status ( Uart * p_uart )

Get current status.

Parameters

p_uart Pointer to a UART instance.

Returns: The current UART status.

uint32_t uart_init	(	Uart *	p_uart,
		const sam_uart_opt_t *	p_uart_opt
	)

Configure UART with the specified parameters.

Note: The PMC and PIOs must be configured first.

Parameters

p_uart	Pointer to a UART instance.
p_uart_opt	Pointer to sam_uart_opt_t instance.

Return values

0	Success.
1	Bad baud rate generator value.

References UART_MCK_DIV, UART_MCK_DIV_MAX_FACTOR, sam_uart_opt::ul_baudrate, sam_uart_opt::ul_mck, and sam_uart_opt::ul_mode.

Referenced by usart_serial_init().

uint32_t uart_is_rx_buf_end ( Uart * p_uart )

Check if one receive buffer is filled.

Parameters

p_uart Pointer to a UART instance.

Return values

1	Receive is completed.
0	Receive is still pending.

uint32_t uart_is_rx_buf_full ( Uart * p_uart )

Check if both receive buffers are full.

Parameters

p_uart Pointer to a UART instance.

Return values

1	Receive buffers are full.
0	Receive buffers are not full.

uint32_t uart_is_rx_ready ( Uart * p_uart )

Check if Received data is ready.

Check if data has been received and loaded in UART_RHR.

Parameters

p_uart Pointer to a UART instance.

Return values

1	One data has been received.
0	No data has been received.

Referenced by usart_serial_is_rx_ready().

uint32_t uart_is_tx_buf_empty ( Uart * p_uart )

Check if both transmit buffers are sent out.

Parameters

p_uart Pointer to a UART instance.

Return values

1	Transmit buffer is empty.
0	Transmit buffer is not empty.

uint32_t uart_is_tx_buf_end ( Uart * p_uart )

Check if one transmit buffer is sent out.

Parameters

p_uart Pointer to a UART instance.

Return values

1	Transmit is completed.
0	Transmit is still pending.

uint32_t uart_is_tx_empty ( Uart * p_uart )

Check if Transmit Hold Register is empty.

Check if the last data written in UART_THR has been loaded in TSR and the last data loaded in TSR has been transmitted.

Parameters

p_uart Pointer to a UART instance.

Return values

1	Transmitter is empty.
0	Transmitter is not empty.

uint32_t uart_is_tx_ready ( Uart * p_uart )

Check if Transmit is Ready.

Check if data has been loaded in UART_THR and is waiting to be loaded in the Transmit Shift Register (TSR).

Parameters

p_uart Pointer to a UART instance.

Return values

1	Data has been transmitted.
0	Transmit is not ready, data pending.

uint32_t uart_read	(	Uart *	p_uart,
		uint8_t *	puc_data
	)

Read from UART Receive Holding Register.

Before reading user should check if rx is ready.

Parameters

p_uart Pointer to a UART instance.

Return values

0	Success.
1	I/O Failure, UART is not ready.

Referenced by main(), and usart_serial_getchar().

void uart_reset ( Uart * p_uart )

Reset UART receiver and transmitter.

Parameters

p_uart Pointer to a UART instance.

void uart_reset_rx ( Uart * p_uart )

Reset UART receiver.

Parameters

p_uart Pointer to a UART instance.

void uart_reset_status ( Uart * p_uart )

Reset status bits.

Parameters

p_uart Pointer to a UART instance.

void uart_reset_tx ( Uart * p_uart )

Reset UART transmitter.

Parameters

p_uart Pointer to a UART instance.

void uart_set_clock_divisor	(	Uart *	p_uart,
		uint16_t	us_divisor
	)

Set UART clock divisor value.

Parameters

p_uart	Pointer to a UART instance.
us_divisor	Value to be set.

void uart_set_sleepwalking	(	Uart *	p_uart,
		uint8_t	ul_low_value,
		bool	cmpmode,
		bool	cmppar,
		uint8_t	ul_high_value
	)

Set sleepwalking match mode.

Parameters

p_uart	Pointer to a UART instance.
ul_low_value	First comparison value for received character.
ul_high_value	Second comparison value for received character.
cmpmode	ture for start condition, false for flag only.
cmppar	ture for parity check, false for no.

References Assert.

void uart_set_write_protection	(	Uart *	p_uart,
		bool	flag
	)

Enables/Disables write protection mode.

Parameters

p_uart	Pointer to a UART instance.
flag	ture for enable, false for disable.

uint32_t uart_write	(	Uart *	p_uart,
		const uint8_t	uc_data
	)

Write to UART Transmit Holding Register Before writing user should check if tx is ready (or empty).

Parameters

p_uart	Pointer to a UART instance.
data	Data to be sent.

Return values

0	Success.
1	I/O Failure, UART is not ready.

Referenced by usart_serial_putchar().

Microchip® Advanced Software Framework

Functions