Simple UART Data Transfer interface

Defines

#define uart_enable_clock(id)   do { } while (0)
 Enable the peripheral clock to UART id.
#define uart_disable_clock(id)   do { } while (0)
 Disable the peripheral clock to UART id.

Functions

void uart_init_priv (uart_t uart, uart_flags_t flags)
 Initializes the UART.
static bool uart_transmit_is_complete_priv (uart_t uart)
 Tests if all data has been transmitted.
static bool uart_tx_buffer_is_empty_priv (uart_t uart)
 Test if tx buffer is empty.
static bool uart_rx_buffer_is_full_priv (uart_t uart)
 Test if rx buffer is full.
static void uart_send_byte_priv (uart_t uart, uint8_t data)
 Send data without checking if the pipline is empty.
static bool uart_put_byte_priv (uart_t uart, uint8_t data)
 Send data if transmitter pipeline is empty.
static bool uart_get_byte_priv (uart_t uart, uint8_t *data)
 Read data if data is available.

UART enable/disable flags



#define UART_FLAG_TX   (1 << 0)
 Enable/disable transmitter.
#define UART_FLAG_RX   (1 << 1)
 Enable/disable receiver.

Initialization



#define uart_enable(uart_id, flags)
 Enable UART transmitter and/or receiver.

Transmitting Data



#define uart_put_string(uart_id, data)
 Send a string to the UART.
#define uart_put_bytes(uart_id, data, len)
 Send a given number of bytes to the UART.
#define uart_transmit_is_complete(uart_id)   uart_transmit_is_complete_priv(uart_t uart)
 Tests if all data has been transmitted.
#define uart_tx_buffer_is_empty(uart_id)   uart_tx_buffer_is_empty_priv(uart_get_regs(uart_id))
 Test if tx buffer is empty.
#define uart_send_byte(uart_id, data)   uart_send_byte_priv(uart_get_regs(uart_id), data)
 Send data without checking if the pipline is empty.
#define uart_put_byte(uart_id, data)   uart_put_byte_priv(uart_get_regs(uart_id), data)
 Sends data if room is left in the tx pipeline.

Receiving Data



#define uart_rx_buffer_is_full(uart_id)   uart_rx_buffer_is_full_priv(uart_get_regs(uart_id))
 Test if rx buffer is full.
#define uart_get_byte(uart_id, data)   uart_get_byte_priv(uart_get_regs(uart_id), data)
 Reads data if data is available in the rx buffer.

Detailed Description

This is a simple and lightweight data transfer interface for UARTs. All transfers are polled, which means that neither the performance nor the power consumption is optimal, but in many cases, it is good enough.

Define Documentation

#define uart_disable_clock ( id   )     do { } while (0)

Disable the peripheral clock to UART id.

This function may be called after disabling a UART in order to conserve a bit of power.

Definition at line 71 of file uart.h.

#define uart_enable ( uart_id,
flags   ) 
Value:
do {                                            \
                uint8_t ctrlb;                          \
                uint8_t _flags = (flags);               \
                void    *regs = uart_get_regs(uart_id); \
                ctrlb = usart_read_reg(regs, CTRLB);    \
                if (_flags & UART_FLAG_TX)              \
                        ctrlb |= USART_BIT(TXEN);       \
                if (_flags & UART_FLAG_RX)              \
                        ctrlb |= USART_BIT(RXEN);       \
                usart_write_reg(regs, CTRLB, ctrlb);    \
        } while (0)

Enable UART transmitter and/or receiver.

Note that this function is not IRQ safe in general (although it happens to be on AVR32.)

Parameters:
uart_id ID of the UART to be enabled
flags Bitwise combination of UART_FLAG_TX and UART_FLAG_RX specifying whether TX, RX or both should be enabled.

Definition at line 72 of file uart_xmega.h.

#define uart_enable_clock ( id   )     do { } while (0)

Enable the peripheral clock to UART id.

This function must be called before starting to initialize a UART which is disabled.

Definition at line 70 of file uart.h.

#define UART_FLAG_RX   (1 << 1)

Enable/disable receiver.

Definition at line 56 of file uart_xmega.h.

#define UART_FLAG_TX   (1 << 0)

Enable/disable transmitter.

Definition at line 55 of file uart_xmega.h.

#define uart_get_byte ( uart_id,
data   )     uart_get_byte_priv(uart_get_regs(uart_id), data)

Reads data if data is available in the rx buffer.

This function checks if data is available in the receive queue and copies it to the user supplied data pointer.

Parameters:
uart_id UART id.
data Pointer to memory where to store rx data.
Return values:
true Data available and stored succesfully.
false No data available.

Definition at line 69 of file uart_xmega.h.

#define uart_put_byte ( uart_id,
data   )     uart_put_byte_priv(uart_get_regs(uart_id), data)

Sends data if room is left in the tx pipeline.

This function checks if there is room left to add new data (max is a byte) in transmitter pipeline and copies the new data into it.

Parameters:
uart_id UART id.
data Data to be sent.
Return values:
true Data was written to send-buffer successfully.
false Data could not be sent becausee data register is not empty.

Definition at line 64 of file uart_xmega.h.

#define uart_put_bytes ( uart_id,
data,
len   ) 
Value:
do {                                                            \
                unsigned int i;                                         \
                for (i = 0; i < len; i++) {                             \
                        while (!uart_put_byte(uart_id, data[i]));       \
                }                                                       \
        } while (0)

Send a given number of bytes to the UART.

Parameters:
uart_id UART id.
data bytes to be sent.
len the number of bytes to be sent.

Definition at line 124 of file uart.h.

#define uart_put_string ( uart_id,
data   ) 
Value:
do {                                                            \
                unsigned int i;                                         \
                for (i = 0; data[i] != 0; i++) {                        \
                        while (!uart_put_byte(uart_id, data[i]));       \
                }                                                       \
        } while (0)

Send a string to the UART.

Parameters:
uart_id UART id.
data String to be sent.

Definition at line 109 of file uart.h.

#define uart_rx_buffer_is_full ( uart_id   )     uart_rx_buffer_is_full_priv(uart_get_regs(uart_id))

Test if rx buffer is full.

Parameters:
uart_id UART id.
Return values:
true if buffer is full.
false if buffer is empty.

Definition at line 67 of file uart_xmega.h.

#define uart_send_byte ( uart_id,
data   )     uart_send_byte_priv(uart_get_regs(uart_id), data)

Send data without checking if the pipline is empty.

Parameters:
uart_id UART id.
data Data to be sent.

Definition at line 62 of file uart_xmega.h.

#define uart_transmit_is_complete ( uart_id   )     uart_transmit_is_complete_priv(uart_t uart)

Tests if all data has been transmitted.

Parameters:
uart_id UART id.
Return values:
true All data has been sent (shift and holding registers empty.)
false There is still data either in the shift register or in the holding register, or the transmitter is disabled.

Definition at line 58 of file uart_xmega.h.

#define uart_tx_buffer_is_empty ( uart_id   )     uart_tx_buffer_is_empty_priv(uart_get_regs(uart_id))

Test if tx buffer is empty.

Parameters:
uart_id UART id.
Return values:
true The TX buffer is empty.
false The TX buffer is full.

Definition at line 60 of file uart_xmega.h.

Function Documentation

static bool uart_get_byte_priv ( uart_t  uart,
uint8_t *  data 
) [inline, static]

Read data if data is available.

For internal use only.

This function checks if data is available in the receive queue and copies it to the user supplied data pointer.

Parameters:
uart Pointer to UART module.
data Pointer to memory where to store rx data.
Return values:
true Data available and written to b successfully.
false No data available.

Definition at line 190 of file uart_xmega.h.

References USART_BIT, and usart_read_reg.

void uart_init_priv ( uart_t  uart,
uart_flags_t  flags 
)

Initializes the UART.

For internal use only.

Parameters:
uart Pointer to UART module.
flags UART configuration flags.
static bool uart_put_byte_priv ( uart_t  uart,
uint8_t  data 
) [inline, static]

Send data if transmitter pipeline is empty.

For internal use only.

This function checks if there is room left to add new data (max is a byte) in transmitter pipeline and copies the new data into it.

Parameters:
uart Pointer to UART module.
data Data to be sent.
Return values:
true Data was written to send-buffer successfully.
false Data could not be sent because data register is not empty.

Definition at line 168 of file uart_xmega.h.

References USART_BIT, usart_read_reg, and usart_write_reg.

static bool uart_rx_buffer_is_full_priv ( uart_t  uart  )  [inline, static]

Test if rx buffer is full.

For internal use only.

Parameters:
uart Pointer to UART module.
Return values:
true if buffer is full.
false if buffer is empty.

Definition at line 137 of file uart_xmega.h.

References USART_BIT, and usart_read_reg.

static void uart_send_byte_priv ( uart_t  uart,
uint8_t  data 
) [inline, static]

Send data without checking if the pipline is empty.

Parameters:
uart Pointer to UART module.
data Data to be sent.

Definition at line 151 of file uart_xmega.h.

References usart_write_reg.

static bool uart_transmit_is_complete_priv ( uart_t  uart  )  [inline, static]

Tests if all data has been transmitted.

For internal use only.

Parameters:
uart Pointer to UART module.
Return values:
true All data has been sent (shift register and THR is empty).
false There is still data either in the shift register or in the THR register, or the transmitter is disabled.

Definition at line 105 of file uart_xmega.h.

References USART_BIT, and usart_read_reg.

static bool uart_tx_buffer_is_empty_priv ( uart_t  uart  )  [inline, static]

Test if tx buffer is empty.

For internal use only.

Parameters:
uart Pointer to UART module.
Return values:
true if buffer is empty.
false if buffer is full.

Definition at line 121 of file uart_xmega.h.

References USART_BIT, and usart_read_reg.

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