Universal Asynchronous Receiver Transceiver (UART)

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

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

Functions
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_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_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...
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_disable

(

Uart *

p_uart

)

Disable UART receiver and transmitter.

Parameters

p_uart

Pointer to a UART instance.

Referenced by buart_if_close().

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.

Referenced by buart_if_close(), buart_if_open(), configure_console(), configure_rx_dma(), freertos_uart_serial_init(), local_uart_handler(), and SB_UART_Handler().

void uart_disable_rx

(

Uart *

p_uart

)

Disable UART receiver.

Parameters

p_uart

Pointer to a UART instance.

Referenced by freertos_uart_serial_init().

void uart_disable_tx

(

Uart *

p_uart

)

Disable UART transmitter.

Parameters

p_uart

Pointer to a UART instance.

Referenced by freertos_uart_serial_init().

void uart_enable

(

Uart *

p_uart

)

Enable UART receiver and transmitter.

Parameters

p_uart

Pointer to a UART instance.

Referenced by usart_stream_reset().

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.

Referenced by buart_if_open(), configure_console(), configure_rx_dma(), freertos_uart_serial_init(), freertos_uart_write_packet_async(), main(), serial_bridge_init(), and serial_bridge_task().

void uart_enable_rx

(

Uart *

p_uart

)

Enable UART receiver.

Parameters

p_uart

Pointer to a UART instance.

Referenced by buart_if_open(), configure_console(), and freertos_uart_serial_init().

void uart_enable_tx

(

Uart *

p_uart

)

Enable UART transmitter.

Parameters

p_uart

Pointer to a UART instance.

Referenced by buart_if_open(), configure_console(), and freertos_uart_serial_init().

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.

Referenced by local_uart_handler().

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.

Referenced by buart_if_open(), and main().

uint32_t uart_get_status

(

Uart *

p_uart

)

Get current status.

Parameters

p_uart

Pointer to a UART instance.

Returns

The current UART status.

Referenced by local_uart_handler(), and UART_Handler().

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 buart_if_open(), config_uart_and_pck(), freertos_uart_serial_init(), reconfigure_console(), serial_bridge_init(), and 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 atCmd_PsMode_Handler(), SB_UART_Handler(), and 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.

Referenced by bt_usart_stream_write_buffer(), buffered_uart_putchar(), usart_stream_write(), and wait_for_message_gone().

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.

Referenced by init_chip(), is_serial_output_done(), main(), SB_UART_Handler(), test_backup_mode(), test_wait_mode(), and user_change_clock().

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 atCmd_PsMode_Handler(), fill_msg_manual(), get_comparison_mode(), get_data_len(), get_impedance_mode(), get_input_voltage(), get_num_value(), get_transmission_att_level(), get_transmission_buffer_id(), get_transmission_channel(), get_transmission_coupling(), get_transmission_data(), get_transmission_disable_rx(), get_transmission_mode(), get_transmission_period(), get_transmission_scheme(), get_voltage(), main(), prvAppPhyTask(), SB_UART_Handler(), send_receive_cmd(), set_adc_test_mode(), UART_Handler(), usart_serial_getchar(), and usart_stream_read().

void uart_reset

(

Uart *

p_uart

)

Reset UART receiver and transmitter.

Parameters

p_uart

Pointer to a UART instance.

Referenced by usart_stream_reset().

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.

Referenced by local_uart_handler().

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.

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 SB_UART_Handler(), serial_bridge_task(), and usart_serial_putchar().