Enumerations
enum	uart_parity_t { UART_PARITY_NONE, UART_PARITY_EVEN, UART_PARITY_ODD }
	UART Parity enumeration.

Functions
static uint	uart_get_index (uart_inst_t *uart)
	Convert UART instance to hardware instance number. More...

uint	uart_init (uart_inst_t *uart, uint baudrate)
	Initialise a UARTPut the UART into a known state, and enable it. Must be called before other functions. More...

void	uart_deinit (uart_inst_t *uart)
	DeInitialise a UARTDisable the UART if it is no longer used. Must be reinitialised before being used again. More...

uint	uart_set_baudrate (uart_inst_t *uart, uint baudrate)
	Set UART baud rateSet baud rate as close as possible to requested, and return actual rate selected. More...

static void	uart_set_hw_flow (uart_inst_t *uart, bool cts, bool rts)
	Set UART flow control CTS/RTS. More...

static void	uart_set_format (uart_inst_t *uart, uint data_bits, uint stop_bits, uart_parity_t parity)
	Set UART data formatConfigure the data format (bits etc() for the UART. More...

static void	uart_set_irq_enables (uart_inst_t *uart, bool rx_has_data, bool tx_needs_data)
	Setup UART interruptsEnable the UART's interrupt output. An interrupt handler will need to be installed prior to calling this function. More...

static bool	uart_is_enabled (uart_inst_t *uart)
	Test if specific UART is enabled. More...

static void	uart_set_fifo_enabled (uart_inst_t *uart, bool enabled)
	Enable/Disable the FIFOs on specified UART. More...

static bool	uart_is_writable (uart_inst_t *uart)
	Determine if space is available in the TX FIFO. More...

static void	uart_tx_wait_blocking (uart_inst_t *uart)
	Wait for the UART TX fifo to be drained. More...

static bool	uart_is_readable (uart_inst_t *uart)
	Determine whether data is waiting in the RX FIFO. More...

static void	uart_write_blocking (uart_inst_t uart, const uint8_t src, size_t len)
	Write to the UART for transmission.This function will block until all the data has been sent to the UART. More...

static void	uart_read_blocking (uart_inst_t uart, uint8_t dst, size_t len)
	Read from the UARTThis function blocks until len characters have been read from the UART. More...

static void	uart_putc_raw (uart_inst_t *uart, char c)
	Write single character to UART for transmission.This function will block until the entire character has been sent. More...

static void	uart_putc (uart_inst_t *uart, char c)
	Write single character to UART for transmission, with optional CR/LF conversionsThis function will block until the character has been sent. More...

static void	uart_puts (uart_inst_t uart, const char s)
	Write string to UART for transmission, doing any CR/LF conversionsThis function will block until the entire string has been sent. More...

static char	uart_getc (uart_inst_t *uart)
	Read a single character from the UARTThis function will block until a character has been read. More...

static void	uart_set_break (uart_inst_t *uart, bool en)
	Assert a break condition on the UART transmission. More...

void	uart_set_translate_crlf (uart_inst_t *uart, bool translate)
	Set CR/LF conversion on UART. More...

static void	uart_default_tx_wait_blocking (void)
	Wait for the default UART's TX FIFO to be drained.

bool	uart_is_readable_within_us (uart_inst_t *uart, uint32_t us)
	Wait for up to a certain number of microseconds for the RX FIFO to be non empty. More...

static uint	uart_get_dreq (uart_inst_t *uart, bool is_tx)
	Return the DREQ to use for pacing transfers to/from a particular UART instance. More...

#define	uart0 ((uart_inst_t *)uart0_hw)
	Identifier for UART instance 0. More...

#define	uart1 ((uart_inst_t *)uart1_hw)
	Identifier for UART instance 1.

Detailed Description

Hardware UART API

RP2040 has 2 identical instances of a UART peripheral, based on the ARM PL011. Each UART can be connected to a number of GPIO pins as defined in the GPIO muxing.

Only the TX, RX, RTS, and CTS signals are connected, meaning that the modem mode and IrDA mode of the PL011 are not supported.

 int main() {
    // Initialise UART 0
    uart_init(uart0, 115200);
    // Set the GPIO pin mux to the UART - 0 is TX, 1 is RX
    gpio_set_function(0, GPIO_FUNC_UART);
    gpio_set_function(1, GPIO_FUNC_UART);
    uart_puts(uart0, "Hello world!");
}

Macro Definition Documentation

◆ uart0

#define uart0 ((uart_inst_t *)uart0_hw)

Identifier for UART instance 0.

The UART identifiers for use in UART functions.

e.g. uart_init(uart1, 48000)

Function Documentation

◆ uart_deinit()

void uart_deinit ( uart_inst_t * uart )

DeInitialise a UARTDisable the UART if it is no longer used. Must be reinitialised before being used again.

Parameters

uart	UART instance. uart0 or uart1

◆ uart_get_dreq()

static uint uart_get_dreq	(	uart_inst_t *	uart,
		bool	is_tx
	)

inlinestatic

Return the DREQ to use for pacing transfers to/from a particular UART instance.

Parameters

uart	UART instance. uart0 or uart1
is_tx	true for sending data to the UART instance, false for receiving data from the UART instance

◆ uart_get_index()

static uint uart_get_index ( uart_inst_t * uart )

inlinestatic

Convert UART instance to hardware instance number.

Parameters

uart	UART instance

Returns: Number of UART, 0 or 1.

◆ uart_getc()

static char uart_getc ( uart_inst_t * uart )

inlinestatic

Read a single character from the UARTThis function will block until a character has been read.

Parameters

uart	UART instance. uart0 or uart1

Returns: The character read.

◆ uart_init()

uint uart_init	(	uart_inst_t *	uart,
		uint	baudrate
	)

Initialise a UARTPut the UART into a known state, and enable it. Must be called before other functions.

Note: There is no guarantee that the baudrate requested will be possible, the nearest will be chosen, and this function will return the configured baud rate.

Parameters

uart	UART instance. uart0 or uart1
baudrate	Baudrate of UART in Hz

Returns: Actual set baudrate

◆ uart_is_enabled()

static bool uart_is_enabled ( uart_inst_t * uart )

inlinestatic

Test if specific UART is enabled.

Parameters

uart	UART instance. uart0 or uart1

Returns: true if the UART is enabled

◆ uart_is_readable()

static bool uart_is_readable ( uart_inst_t * uart )

inlinestatic

Determine whether data is waiting in the RX FIFO.

Parameters

uart	UART instance. uart0 or uart1

Returns: true if the RX FIFO is not empty, otherwise false.

◆ uart_is_readable_within_us()

bool uart_is_readable_within_us	(	uart_inst_t *	uart,
		uint32_t	us
	)

Wait for up to a certain number of microseconds for the RX FIFO to be non empty.

Parameters

uart	UART instance. uart0 or uart1
us	the number of microseconds to wait at most (may be 0 for an instantaneous check)

Returns: true if the RX FIFO became non empty before the timeout, false otherwise

◆ uart_is_writable()

static bool uart_is_writable ( uart_inst_t * uart )

inlinestatic

Determine if space is available in the TX FIFO.

Parameters

uart	UART instance. uart0 or uart1

Returns: false if no space available, true otherwise

◆ uart_putc()

static void uart_putc	(	uart_inst_t *	uart,
		char	c
	)

inlinestatic

Write single character to UART for transmission, with optional CR/LF conversionsThis function will block until the character has been sent.

Parameters

uart	UART instance. uart0 or uart1
c	The character to send

◆ uart_putc_raw()

static void uart_putc_raw	(	uart_inst_t *	uart,
		char	c
	)

inlinestatic

Write single character to UART for transmission.This function will block until the entire character has been sent.

Parameters

uart	UART instance. uart0 or uart1
c	The character to send

◆ uart_puts()

static void uart_puts	(	uart_inst_t *	uart,
		const char *	s
	)

inlinestatic

Write string to UART for transmission, doing any CR/LF conversionsThis function will block until the entire string has been sent.

Parameters

uart	UART instance. uart0 or uart1
s	The null terminated string to send

◆ uart_read_blocking()

static void uart_read_blocking	(	uart_inst_t *	uart,
		uint8_t *	dst,
		size_t	len
	)

inlinestatic

Read from the UARTThis function blocks until len characters have been read from the UART.

Parameters

uart	UART instance. uart0 or uart1
dst	Buffer to accept received bytes
len	The number of bytes to receive.

◆ uart_set_baudrate()

uint uart_set_baudrate	(	uart_inst_t *	uart,
		uint	baudrate
	)

Set UART baud rateSet baud rate as close as possible to requested, and return actual rate selected.

Parameters

uart	UART instance. uart0 or uart1
baudrate	Baudrate in Hz

Returns: Actual set baudrate

◆ uart_set_break()

static void uart_set_break	(	uart_inst_t *	uart,
		bool	en
	)

inlinestatic

Assert a break condition on the UART transmission.

Parameters

uart	UART instance. uart0 or uart1
en	Assert break condition (TX held low) if true. Clear break condition if false.

◆ uart_set_fifo_enabled()

static void uart_set_fifo_enabled	(	uart_inst_t *	uart,
		bool	enabled
	)

inlinestatic

Enable/Disable the FIFOs on specified UART.

Parameters

uart	UART instance. uart0 or uart1
enabled	true to enable FIFO (default), false to disable

◆ uart_set_format()

static void uart_set_format	(	uart_inst_t *	uart,
		uint	data_bits,
		uint	stop_bits,
		uart_parity_t	parity
	)

inlinestatic

Set UART data formatConfigure the data format (bits etc() for the UART.

Parameters

uart	UART instance. uart0 or uart1
data_bits	Number of bits of data. 5..8
stop_bits	Number of stop bits 1..2
parity	Parity option.

◆ uart_set_hw_flow()

static void uart_set_hw_flow	(	uart_inst_t *	uart,
		bool	cts,
		bool	rts
	)

inlinestatic

Set UART flow control CTS/RTS.

Parameters

uart	UART instance. uart0 or uart1
cts	If true enable flow control of TX by clear-to-send input
rts	If true enable assertion of request-to-send output by RX flow control

◆ uart_set_irq_enables()

static void uart_set_irq_enables	(	uart_inst_t *	uart,
		bool	rx_has_data,
		bool	tx_needs_data
	)

inlinestatic

Setup UART interruptsEnable the UART's interrupt output. An interrupt handler will need to be installed prior to calling this function.

Parameters

uart	UART instance. uart0 or uart1
rx_has_data	If true an interrupt will be fired when the RX FIFO contains data.
tx_needs_data	If true an interrupt will be fired when the TX FIFO needs data.

◆ uart_set_translate_crlf()

void uart_set_translate_crlf	(	uart_inst_t *	uart,
		bool	translate
	)

Set CR/LF conversion on UART.

Parameters

uart	UART instance. uart0 or uart1
translate	If true, convert line feeds to carriage return on transmissions

◆ uart_tx_wait_blocking()

static void uart_tx_wait_blocking ( uart_inst_t * uart )

inlinestatic

Wait for the UART TX fifo to be drained.

Parameters

uart	UART instance. uart0 or uart1

◆ uart_write_blocking()

static void uart_write_blocking	(	uart_inst_t *	uart,
		const uint8_t *	src,
		size_t	len
	)

inlinestatic

Write to the UART for transmission.This function will block until all the data has been sent to the UART.

Parameters

uart	UART instance. uart0 or uart1
src	The bytes to send
len	The number of bytes to send

Enumerations

Functions

Detailed Description

Macro Definition Documentation

◆ uart0

Function Documentation

◆ uart_deinit()

◆ uart_get_dreq()

◆ uart_get_index()

◆ uart_getc()

◆ uart_init()

◆ uart_is_enabled()

◆ uart_is_readable()

◆ uart_is_readable_within_us()

◆ uart_is_writable()

◆ uart_putc()

◆ uart_putc_raw()

◆ uart_puts()

◆ uart_read_blocking()

◆ uart_set_baudrate()

◆ uart_set_break()

◆ uart_set_fifo_enabled()

◆ uart_set_format()

◆ uart_set_hw_flow()

◆ uart_set_irq_enables()

◆ uart_set_translate_crlf()

◆ uart_tx_wait_blocking()

◆ uart_write_blocking()