ASF Wizard

• USART - Serial interface (service): Common API which abstracts the user from directly accessing the register and provides a generic serial interface using USART.
• PIO - Parallel Input/Output Controller (driver): The Parallel Input/Output Controller manages up to 32 fully programmable input/output lines. Each I/O line may be dedicated as a general-purpose I/O or be assigned to a function of an embedded peripheral. This assures effective optimization of the pins of a product.

src\config\conf_board.h

#ifndef CONF_BOARD_H

#define CONF_BOARD_H

#define CONSOLE_UART (Usart *)USART0

/** Enable Com Port. */

#define CONF_BOARD_UART_CONSOLE

#endif // CONF_BOARD_H

src\config\conf_uart_serial.h

#ifndef CONF_USART_SERIAL_H

#define CONF_USART_SERIAL_H

/* A reference setting for USART */

/** USART Interface */

#define CONF_UART CONSOLE_UART

/** Baudrate setting */

#define CONF_UART_BAUDRATE 115200

/** Character length setting */

#define CONF_UART_CHAR_LENGTH US_MR_CHRL_8_BIT

/** Parity setting */

#define CONF_UART_PARITY US_MR_PAR_NO

/** Stop bits setting */

#define CONF_UART_STOP_BITS US_MR_NBSTOP_1_BIT

#define USART_SERIAL CONF_UART

#define USART_SERIAL_ID ID_USART0

#define USART_SERIAL_BAUDRATE CONF_UART_BAUDRATE

#define USART_SERIAL_CHAR_LENGTH CONF_UART_CHAR_LENGTH

#define USART_SERIAL_PARITY CONF_UART_PARITY

#define USART_SERIAL_STOP_BIT CONF_UART_STOP_BITS

#define USART_SERIAL_IRQ USART0_IRQn

#define USART_SERIAL_ISR_HANDLER USART0_Handler

#define USART_SERIAL_RX_BUFFER_SIZE 128

#define USART_SERIAL_TX_BUFFER_SIZE 128

#define PINS_USART0_PIO PIOA

#define PINS_USART0_ID USART_SERIAL_ID

#define PINS_USART0_TYPE PIO_PERIPH_A

#define PINS_USART0_ATTR PIO_DEFAULT

#define PINS_USART0_MASK (PIO_PA5A_RXD0 | PIO_PA6A_TXD0)

#endif /* CONF_USART_SERIAL_H_INCLUDED */

Examples

#include "conf_uart_serial.h"

#include <asf.h>

volatile uint8_t rx_buffer[USART_SERIAL_RX_BUFFER_SIZE];

volatile uint16_t rx_buffer_tail = 0;

volatile uint16_t rx_buffer_head = 0;

void serial_init(void) {

pio_configure(

PINS_USART0_PIO, PINS_USART0_TYPE, PINS_USART0_MASK, PINS_USART0_ATTR);

pmc_enable_periph_clk(USART_SERIAL_ID);

sysclk_enable_peripheral_clock(USART_SERIAL_ID);

const sam_usart_opt_t usart_console_settings

= {.baudrate = USART_SERIAL_BAUDRATE,

.char_length = USART_SERIAL_CHAR_LENGTH,

.parity_type = USART_SERIAL_PARITY,

.stop_bits = USART_SERIAL_STOP_BIT,

.channel_mode = US_MR_CHMODE_NORMAL};

usart_init_rs232(USART_SERIAL, &usart_console_settings, F_CPU);

usart_enable_tx(USART_SERIAL);

usart_enable_rx(USART_SERIAL);

usart_enable_interrupt(USART_SERIAL, US_IER_RXRDY);

NVIC_EnableIRQ(USART_SERIAL_IRQ);

}

uint16_t serial_available(void) {

return (USART_SERIAL_RX_BUFFER_SIZE + rx_buffer_head - rx_buffer_tail)

% USART_SERIAL_RX_BUFFER_SIZE;

}

char serial_read(void) {

if(rx_buffer_head == rx_buffer_tail) return 0;

else {

uint8_t temp = rx_buffer[rx_buffer_tail];

rx_buffer_tail = (rx_buffer_tail + 1) % USART_SERIAL_RX_BUFFER_SIZE;

return temp;

}

}

int main(void) {

sysclk_init();

board_init();

/* Insert application code here, after the board has been initialized. */

wdt_disable(WDT);

serial_init();

for(;;) {

if(serial_available()) { usart_write(USART_SERIAL, serial_read()); }

}

}

ISR(USART_SERIAL_ISR_HANDLER) {

if(usart_is_rx_ready(USART_SERIAL)) {

usart_read(USART_SERIAL, &rx_buffer[rx_buffer_head]);

rx_buffer_head = (rx_buffer_head + 1) % USART_SERIAL_RX_BUFFER_SIZE;

if(rx_buffer_head == rx_buffer_tail) {

rx_buffer_tail = (rx_buffer_tail + 1) % USART_SERIAL_RX_BUFFER_SIZE;

}

}

}