UART Library

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Detailed Description

Interrupt UART library using the built-in UART with transmit and receive circular buffers.

 #include <uart.h> 

This library can be used to transmit and receive data through the built in UART.

An interrupt is generated when the UART has finished transmitting or receiving a byte. The interrupt handling routines use circular buffers for buffering received and transmitted data.

The UART_RX_BUFFER_SIZE and UART_TX_BUFFER_SIZE constants define the size of the circular buffers in bytes. Note that these constants must be a power of 2. You may need to adapt this constants to your target and your application by adding CDEFS += -DUART_RX_BUFFER_SIZE=nn -DUART_RX_BUFFER_SIZE=nn to your Makefile.

Note:

Based on Atmel Application Note AVR306

Author:

Peter Fleury pfleury@gmx.ch http://jump.to/fleury

Defines
#define	UART_BAUD_SELECT(baudRate, xtalCpu)   ((xtalCpu)/((baudRate)*16l)-1)
	UART Baudrate Expression.
#define	UART_BAUD_SELECT_DOUBLE_SPEED(baudRate, xtalCpu)   (((xtalCpu)/((baudRate)*8l)-1)|0x8000)
	UART Baudrate Expression for ATmega double speed mode.
#define	UART_RX_BUFFER_SIZE   32
#define	UART_TX_BUFFER_SIZE   32
#define	UART_FRAME_ERROR   0x0800
#define	UART_OVERRUN_ERROR   0x0400
#define	UART_BUFFER_OVERFLOW   0x0200
#define	UART_NO_DATA   0x0100
#define	uart_puts_P(__s)   uart_puts_p(PSTR(__s))
	Macro to automatically put a string constant into program memory.
#define	uart1_puts_P(__s)   uart1_puts_p(PSTR(__s))
	Macro to automatically put a string constant into program memory.
Functions
void	uart_init (unsigned int baudrate)
	Initialize UART and set baudrate.
unsigned int	uart_getc (void)
	Get received byte from ringbuffer.
void	uart_putc (unsigned char data)
	Put byte to ringbuffer for transmitting via UART.
void	uart_puts (const char *s)
	Put string to ringbuffer for transmitting via UART.
void	uart_puts_p (const char *s)
	Put string from program memory to ringbuffer for transmitting via UART.
void	uart1_init (unsigned int baudrate)
	Initialize USART1 (only available on selected ATmegas).
unsigned int	uart1_getc (void)
	Get received byte of USART1 from ringbuffer. (only available on selected ATmega).
void	uart1_putc (unsigned char data)
	Put byte to ringbuffer for transmitting via USART1 (only available on selected ATmega).
void	uart1_puts (const char *s)
	Put string to ringbuffer for transmitting via USART1 (only available on selected ATmega).
void	uart1_puts_p (const char *s)
	Put string from program memory to ringbuffer for transmitting via USART1 (only available on selected ATmega).

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Define Documentation

#define UART_BAUD_SELECT (  baudRate, xtalCpu   )     ((xtalCpu)/((baudRate)*16l)-1)

UART Baudrate Expression. Parameters: xtalcpu  system clock in Mhz, e.g. 4000000L for 4Mhz baudrate  baudrate in bps, e.g. 1200, 2400, 9600

#define UART_BAUD_SELECT_DOUBLE_SPEED (  baudRate, xtalCpu   )     (((xtalCpu)/((baudRate)*8l)-1)|0x8000)

UART Baudrate Expression for ATmega double speed mode. Parameters: xtalcpu  system clock in Mhz, e.g. 4000000L for 4Mhz baudrate  baudrate in bps, e.g. 1200, 2400, 9600

#define UART_RX_BUFFER_SIZE   32

Size of the circular receive buffer, must be power of 2

#define UART_TX_BUFFER_SIZE   32

Size of the circular transmit buffer, must be power of 2

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Function Documentation

void uart_init (  unsigned int  baudrate  )

Initialize UART and set baudrate. Parameters: baudrate  Specify baudrate using macro UART_BAUD_SELECT() Returns: none

unsigned int uart_getc (  void   )

Get received byte from ringbuffer. Returns in the lower byte the received character and in the higher byte the last receive error. UART_NO_DATA is returned when no data is available. Parameters: void  Returns: lower byte: received byte from ringbuffer higher byte: last receive status 0 successfully received data from UART UART_NO_DATA no receive data available UART_BUFFER_OVERFLOW Receive ringbuffer overflow. We are not reading the receive buffer fast enough, one or more received character have been dropped UART_OVERRUN_ERROR Overrun condition by UART. A character already present in the UART UDR register was not read by the interrupt handler before the next character arrived, one or more received characters have been dropped. UART_FRAME_ERROR Framing Error by UART

void uart_putc (  unsigned char  data  )

Put byte to ringbuffer for transmitting via UART. Parameters: data  byte to be transmitted Returns: none

void uart_puts (  const char *  s  )

Put string to ringbuffer for transmitting via UART. The string is buffered by the uart library in a circular buffer and one character at a time is transmitted to the UART using interrupts. Blocks if it can not write the whole string into the circular buffer. Parameters: s  string to be transmitted Returns: none

void uart_puts_p (  const char *  s  )

Put string from program memory to ringbuffer for transmitting via UART. The string is buffered by the uart library in a circular buffer and one character at a time is transmitted to the UART using interrupts. Blocks if it can not write the whole string into the circular buffer. Parameters: s  program memory string to be transmitted Returns: none See also: uart_puts_P

void uart1_init (  unsigned int  baudrate  )

Initialize USART1 (only available on selected ATmegas). See also: uart_init

unsigned int uart1_getc (  void   )

Get received byte of USART1 from ringbuffer. (only available on selected ATmega). See also: uart_getc

void uart1_putc (  unsigned char  data  )

Put byte to ringbuffer for transmitting via USART1 (only available on selected ATmega). See also: uart_putc

void uart1_puts (  const char *  s  )

Put string to ringbuffer for transmitting via USART1 (only available on selected ATmega). See also: uart_puts

void uart1_puts_p (  const char *  s  )

Put string from program memory to ringbuffer for transmitting via USART1 (only available on selected ATmega). See also: uart_puts_p

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