uart.h File Reference

#include <inttypes.h>
#include <stdlib.h>
#include <stdio.h>
#include <avr/io.h>
#include <util/atomic.h>
#include <util/setbaud.h>

Go to the source code of this file.

Data Structures
struct	DirBuff
	Presenting a circular buffer. More...
struct	CBuffer
	This holds the circular buffers. More...
struct	UARTcfg
	A struct to configure the UART. More...

Macros
#define	F_CPU   16000000UL /* 16MHz µc */
#define	BAUD   9600L
#define	UARTAVR_VERSION_MAJOR   0
	Version major.
#define	UARTAVR_VERSION_MINOR   3
	Version minor.
#define	UARTAVR_VERSION_PATCH   0
	Version patch.
#define	CR   "\n\r"
	Define the line ending you need. This one will work with minicom on linux. More...
#define	CR_PRINTF   "\r"
	If set this sign well be send whenever puts_printf_UART() sees a newline character.
#define	BUFFSIZE   64
	The buffer size for the RX and TX buffers.

Enumerations
enum	DIR_BUFFS { RX_BUFF, TX_BUFF }
	Identifier for direction buffer. More...

Functions
void	cb_init (void)
	Initializes the circular buffer structure. More...
void	get_direction_buffer (enum DIR_BUFFS dir, struct DirBuff **dbuff)
	Get a direction buffer struct from CBuffer. More...
uint8_t	cb_pop (char *c, enum DIR_BUFFS dir)
	Get one byte from the circular buffer. More...
uint8_t	cp_push (char c, enum DIR_BUFFS dir)
	Put one byte in the circular buffer. More...
void	init_uart_cfg (struct UARTcfg *cfg)
	Init a cfg struct with the default values. More...
void	init_UART (const struct UARTcfg *cfg)
	Initialize the UART on the microcontroller. More...
void	put_UART (const char c)
	Send a single character. More...
void	puts_UART (const char *s)
	Write a string to the UART buffer. More...
uint8_t	get_UART (char *s)
	Retrieve one char from the buffer. More...
uint8_t	gets_UART (char *s)
	Get all data from the circular buffer. More...
int	puts_printf_UART (char c, FILE *stream)
	The FILE stream method for uartavr_stdout. More...

Variables
struct CBuffer	cb

Detailed Description

Author

Christian Rapp

Date

2016

Copyright

BSD-3-Clause

Precondition

This library was written and tested fo the Atmege328P microcontroller. You may need to change the registers if you want to port this to a different AVR.

uartavr is a simple interrupt driven UART implementation for Atmel AVRs. This library uses a circular buffer data structure to store data that should be send or was received. In general the user does not have to interact directly with this buffer as there are some convenience methods already available.

In order to use this implementation you have to use sei which enables interrupts by setting the global interrupt mask.

Macro Definition Documentation

CR

#define CR   "\n\r"

Define the line ending you need. This one will work with minicom on linux.

This will automatically appended to all strings that you want to send using puts_UART()

Enumeration Type Documentation

DIR_BUFFS

enum DIR_BUFFS

Identifier for direction buffer.

Enumerator
RX_BUFF	RX Buffer identifier
TX_BUFF	TX Buffer identifier

Function Documentation

cb_init()

void cb_init

(

void

)

Initializes the circular buffer structure.

Warning

Do not call this function yourself. The init_UART() function takes care of this.

cb_pop()

uint8_t cb_pop	(	char *	c,
		enum DIR_BUFFS	dir
	)

Get one byte from the circular buffer.

Parameters

c	Pointer to char variable
dir	Get the byte from the TX or RX buffer

Returns

0 If the byte has been retrieved, 1 if the buffer is empty

cp_push()

uint8_t cp_push	(	char	c,
		enum DIR_BUFFS	dir
	)

Put one byte in the circular buffer.

Parameters

c	A char variable
dir	Put the byte on the TX or RX buffer

Returns

0 If the byte has written successfully, 1 if the buffer is full

get_direction_buffer()

void get_direction_buffer	(	enum DIR_BUFFS	dir,
		struct DirBuff **	dbuff
	)

Get a direction buffer struct from CBuffer.

Parameters

dir	RX or TX
dbuff	** to a DirBuff struct

get_UART()

uint8_t get_UART

(

char *

s

)

Retrieve one char from the buffer.

Parameters

s	Pointer to a char variable

Returns

0 If character was retrieved, 1 otherwise

gets_UART()

uint8_t gets_UART

(

char *

s

)

Get all data from the circular buffer.

Parameters

s	Pointer an array which this function uses to store the data from cb

Returns

0 on success or 1 if something went wrong

Warning

Make sure your char array has enough room for the data in the circular buffer plus \0 as termination character. You can get the numbers of items in the buffer with DirBuff::items

init_UART()

void init_UART

(

const struct UARTcfg *

cfg

)

Initialize the UART on the microcontroller.

Parameters

cfg	Pointer to a UARTcfg struct with the configuration for the UART

Some configuration options are currently fixed. The UART will always be setup in 8N1 mode. This may be changed in the future.

This method also initializes a circular buffer. So there is no need to call cb_init() yourself.

init_uart_cfg()

void init_uart_cfg

(

struct UARTcfg *

cfg

)

Init a cfg struct with the default values.

Parameters

cfg

put_UART()

void put_UART

(

const char

c

)

Send a single character.

Parameters

c	The character to send

puts_printf_UART()

int puts_printf_UART	(	char	c,
		FILE *	stream
	)

The FILE stream method for uartavr_stdout.

Parameters

c	The character to write into the circular buffer
stream

Returns

Always 0 currently

init_UART() will bind uartavr_stdout FILE stream to stdout. This way everything that will be written to stdout (e.g. with printf) will effectively be written in the circular buffer of uartavr. You need to link your application against printf_ftl or printf_min to make this work.

See also

printf_examples.c in examples subfolder

puts_UART()

void puts_UART

(

const char *

s

)

Write a string to the UART buffer.

Parameters

s	The string you want to send

The macro CR will automatically appended to your string so you do not have to worry about this.

Variable Documentation

cb

struct CBuffer cb

Global instance of the circular buffer