Skip to content

Instantly share code, notes, and snippets.

@cdesch

cdesch/uart.c

Created May 1, 2012
Embed
What would you like to do?
UART Library
/*************************************************************************
Title: Interrupt UART library with receive/transmit circular buffers
Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
File: $Id: uart.c,v 1.6.2.2 2009/11/29 08:56:12 Peter Exp $
Software: AVR-GCC 4.1, AVR Libc 1.4.6 or higher
Hardware: any AVR with built-in UART,
License: GNU General Public License
DESCRIPTION:
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 variables define
the buffer size in bytes. Note that these variables must be a
power of 2.
USAGE:
Refere to the header file uart.h for a description of the routines.
See also example test_uart.c.
NOTES:
Based on Atmel Application Note AVR306
LICENSE:
Copyright (C) 2006 Peter Fleury
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
*************************************************************************/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include "uart.h"
/*
* constants and macros
*/
/* size of RX/TX buffers */
#define UART_RX_BUFFER_MASK ( UART_RX_BUFFER_SIZE - 1)
#define UART_TX_BUFFER_MASK ( UART_TX_BUFFER_SIZE - 1)
#if ( UART_RX_BUFFER_SIZE & UART_RX_BUFFER_MASK )
#error RX buffer size is not a power of 2
#endif
#if ( UART_TX_BUFFER_SIZE & UART_TX_BUFFER_MASK )
#error TX buffer size is not a power of 2
#endif
#if defined(__AVR_AT90S2313__) \
|| defined(__AVR_AT90S4414__) || defined(__AVR_AT90S4434__) \
|| defined(__AVR_AT90S8515__) || defined(__AVR_AT90S8535__) \
|| defined(__AVR_ATmega103__)
/* old AVR classic or ATmega103 with one UART */
#define AT90_UART
#define UART0_RECEIVE_INTERRUPT SIG_UART_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_UART_DATA
#define UART0_STATUS USR
#define UART0_CONTROL UCR
#define UART0_DATA UDR
#define UART0_UDRIE UDRIE
#elif defined(__AVR_AT90S2333__) || defined(__AVR_AT90S4433__)
/* old AVR classic with one UART */
#define AT90_UART
#define UART0_RECEIVE_INTERRUPT SIG_UART_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_UART_DATA
#define UART0_STATUS UCSRA
#define UART0_CONTROL UCSRB
#define UART0_DATA UDR
#define UART0_UDRIE UDRIE
#elif defined(__AVR_ATmega8__) || defined(__AVR_ATmega16__) || defined(__AVR_ATmega32__) \
|| defined(__AVR_ATmega8515__) || defined(__AVR_ATmega8535__) \
|| defined(__AVR_ATmega323__)
/* ATmega with one USART */
#define ATMEGA_USART
#define UART0_RECEIVE_INTERRUPT SIG_UART_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_UART_DATA
#define UART0_STATUS UCSRA
#define UART0_CONTROL UCSRB
#define UART0_DATA UDR
#define UART0_UDRIE UDRIE
#elif defined(__AVR_ATmega163__)
/* ATmega163 with one UART */
#define ATMEGA_UART
#define UART0_RECEIVE_INTERRUPT SIG_UART_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_UART_DATA
#define UART0_STATUS UCSRA
#define UART0_CONTROL UCSRB
#define UART0_DATA UDR
#define UART0_UDRIE UDRIE
#elif defined(__AVR_ATmega162__)
/* ATmega with two USART */
#define ATMEGA_USART0
#define ATMEGA_USART1
#define UART0_RECEIVE_INTERRUPT SIG_USART0_RECV
#define UART1_RECEIVE_INTERRUPT SIG_USART1_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_USART0_DATA
#define UART1_TRANSMIT_INTERRUPT SIG_USART1_DATA
#define UART0_STATUS UCSR0A
#define UART0_CONTROL UCSR0B
#define UART0_DATA UDR0
#define UART0_UDRIE UDRIE0
#define UART1_STATUS UCSR1A
#define UART1_CONTROL UCSR1B
#define UART1_DATA UDR1
#define UART1_UDRIE UDRIE1
#elif defined(__AVR_ATmega64__) || defined(__AVR_ATmega128__)
/* ATmega with two USART */
#define ATMEGA_USART0
#define ATMEGA_USART1
#define UART0_RECEIVE_INTERRUPT SIG_UART0_RECV
#define UART1_RECEIVE_INTERRUPT SIG_UART1_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_UART0_DATA
#define UART1_TRANSMIT_INTERRUPT SIG_UART1_DATA
#define UART0_STATUS UCSR0A
#define UART0_CONTROL UCSR0B
#define UART0_DATA UDR0
#define UART0_UDRIE UDRIE0
#define UART1_STATUS UCSR1A
#define UART1_CONTROL UCSR1B
#define UART1_DATA UDR1
#define UART1_UDRIE UDRIE1
#elif defined(__AVR_ATmega161__)
/* ATmega with UART */
#error "AVR ATmega161 currently not supported by this libaray !"
#elif defined(__AVR_ATmega169__)
/* ATmega with one USART */
#define ATMEGA_USART
#define UART0_RECEIVE_INTERRUPT SIG_USART_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_USART_DATA
#define UART0_STATUS UCSRA
#define UART0_CONTROL UCSRB
#define UART0_DATA UDR
#define UART0_UDRIE UDRIE
#elif defined(__AVR_ATmega48__) ||defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__) || defined(__AVR_ATmega48P__) || defined(__AVR_ATmega88P__) || defined(__AVR_ATmega168P__) || defined(__AVR_ATmega328P__)
/* ATmega with one USART */
#define ATMEGA_USART0
#define UART0_RECEIVE_INTERRUPT SIG_USART_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_USART_DATA
#define UART0_STATUS UCSR0A
#define UART0_CONTROL UCSR0B
#define UART0_DATA UDR0
#define UART0_UDRIE UDRIE0
#elif defined(__AVR_ATtiny2313__)
#define ATMEGA_USART
#define UART0_RECEIVE_INTERRUPT SIG_USART0_RX
#define UART0_TRANSMIT_INTERRUPT SIG_USART0_UDRE
#define UART0_STATUS UCSRA
#define UART0_CONTROL UCSRB
#define UART0_DATA UDR
#define UART0_UDRIE UDRIE
#elif defined(__AVR_ATmega329__) ||defined(__AVR_ATmega3290__) ||\
defined(__AVR_ATmega649__) ||defined(__AVR_ATmega6490__) ||\
defined(__AVR_ATmega325__) ||defined(__AVR_ATmega3250__) ||\
defined(__AVR_ATmega645__) ||defined(__AVR_ATmega6450__)
/* ATmega with one USART */
#define ATMEGA_USART0
#define UART0_RECEIVE_INTERRUPT SIG_UART_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_UART_DATA
#define UART0_STATUS UCSR0A
#define UART0_CONTROL UCSR0B
#define UART0_DATA UDR0
#define UART0_UDRIE UDRIE0
#elif defined(__AVR_ATmega2560__) || defined(__AVR_ATmega2561__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega1281__) || defined(__AVR_ATmega640__)
/* ATmega with two USART */
#define ATMEGA_USART0
#define ATMEGA_USART1
#define UART0_RECEIVE_INTERRUPT USART0_RX_vect
#define UART1_RECEIVE_INTERRUPT USART1_RX_vect
#define UART0_TRANSMIT_INTERRUPT USART0_TX_vect
#define UART1_TRANSMIT_INTERRUPT USART1_TX_vect
#define UART0_STATUS UCSR0A
#define UART0_CONTROL UCSR0B
#define UART0_DATA UDR0
#define UART0_UDRIE UDRIE0
#define UART1_STATUS UCSR1A
#define UART1_CONTROL UCSR1B
#define UART1_DATA UDR1
#define UART1_UDRIE UDRIE1
#elif defined(__AVR_ATmega644__)
/* ATmega with one USART */
#define ATMEGA_USART0
#define UART0_RECEIVE_INTERRUPT SIG_USART_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_USART_DATA
#define UART0_STATUS UCSR0A
#define UART0_CONTROL UCSR0B
#define UART0_DATA UDR0
#define UART0_UDRIE UDRIE0
#elif defined(__AVR_ATmega164P__) || defined(__AVR_ATmega324P__) || defined(__AVR_ATmega644P__)
/* ATmega with two USART */
#define ATMEGA_USART0
#define ATMEGA_USART1
#define UART0_RECEIVE_INTERRUPT SIG_USART_RECV
#define UART1_RECEIVE_INTERRUPT SIG_USART1_RECV
#define UART0_TRANSMIT_INTERRUPT SIG_USART_DATA
#define UART1_TRANSMIT_INTERRUPT SIG_USART1_DATA
#define UART0_STATUS UCSR0A
#define UART0_CONTROL UCSR0B
#define UART0_DATA UDR0
#define UART0_UDRIE UDRIE0
#define UART1_STATUS UCSR1A
#define UART1_CONTROL UCSR1B
#define UART1_DATA UDR1
#define UART1_UDRIE UDRIE1
#else
#error "no UART definition for MCU available"
#endif
/*
* module global variables
*/
static volatile unsigned char UART_TxBuf[UART_TX_BUFFER_SIZE];
static volatile unsigned char UART_RxBuf[UART_RX_BUFFER_SIZE];
static volatile unsigned char UART_TxHead;
static volatile unsigned char UART_TxTail;
static volatile unsigned char UART_RxHead;
static volatile unsigned char UART_RxTail;
static volatile unsigned char UART_LastRxError;
#if defined( ATMEGA_USART1 )
static volatile unsigned char UART1_TxBuf[UART_TX_BUFFER_SIZE];
static volatile unsigned char UART1_RxBuf[UART_RX_BUFFER_SIZE];
static volatile unsigned char UART1_TxHead;
static volatile unsigned char UART1_TxTail;
static volatile unsigned char UART1_RxHead;
static volatile unsigned char UART1_RxTail;
static volatile unsigned char UART1_LastRxError;
#endif
ISR(UART0_RECEIVE_INTERRUPT)
/*************************************************************************
Function: UART Receive Complete interrupt
Purpose: called when the UART has received a character
**************************************************************************/
{
unsigned char tmphead;
unsigned char data;
unsigned char usr;
unsigned char lastRxError;
/* read UART status register and UART data register */
usr = UART0_STATUS;
data = UART0_DATA;
/* */
#if defined( AT90_UART )
lastRxError = (usr & (_BV(FE)|_BV(DOR)) );
#elif defined( ATMEGA_USART )
lastRxError = (usr & (_BV(FE)|_BV(DOR)) );
#elif defined( ATMEGA_USART0 )
lastRxError = (usr & (_BV(FE0)|_BV(DOR0)) );
#elif defined ( ATMEGA_UART )
lastRxError = (usr & (_BV(FE)|_BV(DOR)) );
#endif
/* calculate buffer index */
tmphead = ( UART_RxHead + 1) & UART_RX_BUFFER_MASK;
if ( tmphead == UART_RxTail ) {
/* error: receive buffer overflow */
lastRxError = UART_BUFFER_OVERFLOW >> 8;
}else{
/* store new index */
UART_RxHead = tmphead;
/* store received data in buffer */
UART_RxBuf[tmphead] = data;
}
UART_LastRxError = lastRxError;
}
ISR(UART0_TRANSMIT_INTERRUPT)
/*************************************************************************
Function: UART Data Register Empty interrupt
Purpose: called when the UART is ready to transmit the next byte
**************************************************************************/
{
unsigned char tmptail;
if ( UART_TxHead != UART_TxTail) {
/* calculate and store new buffer index */
tmptail = (UART_TxTail + 1) & UART_TX_BUFFER_MASK;
UART_TxTail = tmptail;
/* get one byte from buffer and write it to UART */
UART0_DATA = UART_TxBuf[tmptail]; /* start transmission */
}else{
/* tx buffer empty, disable UDRE interrupt */
UART0_CONTROL &= ~_BV(UART0_UDRIE);
}
}
/*************************************************************************
Function: uart_init()
Purpose: initialize UART and set baudrate
Input: baudrate using macro UART_BAUD_SELECT()
Returns: none
**************************************************************************/
void uart_init(unsigned int baudrate)
{
UART_TxHead = 0;
UART_TxTail = 0;
UART_RxHead = 0;
UART_RxTail = 0;
#if defined( AT90_UART )
/* set baud rate */
UBRR = (unsigned char)baudrate;
/* enable UART receiver and transmmitter and receive complete interrupt */
UART0_CONTROL = _BV(RXCIE)|_BV(RXEN)|_BV(TXEN);
#elif defined (ATMEGA_USART)
/* Set baud rate */
if ( baudrate & 0x8000 )
{
UART0_STATUS = (1<<U2X); //Enable 2x speed
baudrate &= ~0x8000;
}
UBRRH = (unsigned char)(baudrate>>8);
UBRRL = (unsigned char) baudrate;
/* Enable USART receiver and transmitter and receive complete interrupt */
UART0_CONTROL = _BV(RXCIE)|(1<<RXEN)|(1<<TXEN);
/* Set frame format: asynchronous, 8data, no parity, 1stop bit */
#ifdef URSEL
UCSRC = (1<<URSEL)|(3<<UCSZ0);
#else
UCSRC = (3<<UCSZ0);
#endif
#elif defined (ATMEGA_USART0 )
/* Set baud rate */
if ( baudrate & 0x8000 )
{
UART0_STATUS = (1<<U2X0); //Enable 2x speed
baudrate &= ~0x8000;
}
UBRR0H = (unsigned char)(baudrate>>8);
UBRR0L = (unsigned char) baudrate;
/* Enable USART receiver and transmitter and receive complete interrupt */
UART0_CONTROL = _BV(RXCIE0)|(1<<RXEN0)|(1<<TXEN0);
/* Set frame format: asynchronous, 8data, no parity, 1stop bit */
#ifdef URSEL0
UCSR0C = (1<<URSEL0)|(3<<UCSZ00);
#else
UCSR0C = (3<<UCSZ00);
#endif
#elif defined ( ATMEGA_UART )
/* set baud rate */
if ( baudrate & 0x8000 )
{
UART0_STATUS = (1<<U2X); //Enable 2x speed
baudrate &= ~0x8000;
}
UBRRHI = (unsigned char)(baudrate>>8);
UBRR = (unsigned char) baudrate;
/* Enable UART receiver and transmitter and receive complete interrupt */
UART0_CONTROL = _BV(RXCIE)|(1<<RXEN)|(1<<TXEN);
#endif
}/* uart_init */
/*************************************************************************
Function: uart_getc()
Purpose: return byte from ringbuffer
Returns: lower byte: received byte from ringbuffer
higher byte: last receive error
**************************************************************************/
unsigned int uart_getc(void)
{
unsigned char tmptail;
unsigned char data;
if ( UART_RxHead == UART_RxTail ) {
return UART_NO_DATA; /* no data available */
}
/* calculate /store buffer index */
tmptail = (UART_RxTail + 1) & UART_RX_BUFFER_MASK;
UART_RxTail = tmptail;
/* get data from receive buffer */
data = UART_RxBuf[tmptail];
return (UART_LastRxError << 8) + data;
}/* uart_getc */
/*************************************************************************
Function: uart_putc()
Purpose: write byte to ringbuffer for transmitting via UART
Input: byte to be transmitted
Returns: none
**************************************************************************/
void uart_putc(unsigned char data)
{
unsigned char tmphead;
tmphead = (UART_TxHead + 1) & UART_TX_BUFFER_MASK;
while ( tmphead == UART_TxTail ){
;/* wait for free space in buffer */
}
UART_TxBuf[tmphead] = data;
UART_TxHead = tmphead;
/* enable UDRE interrupt */
UART0_CONTROL |= _BV(UART0_UDRIE);
}/* uart_putc */
/*************************************************************************
Function: uart_puts()
Purpose: transmit string to UART
Input: string to be transmitted
Returns: none
**************************************************************************/
void uart_puts(const char *s )
{
while (*s)
uart_putc(*s++);
}/* uart_puts */
/*************************************************************************
Function: uart_puts_p()
Purpose: transmit string from program memory to UART
Input: program memory string to be transmitted
Returns: none
**************************************************************************/
void uart_puts_p(const char *progmem_s )
{
register char c;
while ( (c = pgm_read_byte(progmem_s++)) )
uart_putc(c);
}/* uart_puts_p */
/*
* these functions are only for ATmegas with two USART
*/
#if defined( ATMEGA_USART1 )
ISR(UART1_RECEIVE_INTERRUPT)
/*************************************************************************
Function: UART1 Receive Complete interrupt
Purpose: called when the UART1 has received a character
**************************************************************************/
{
unsigned char tmphead;
unsigned char data;
unsigned char usr;
unsigned char lastRxError;
/* read UART status register and UART data register */
usr = UART1_STATUS;
data = UART1_DATA;
/* */
lastRxError = (usr & (_BV(FE1)|_BV(DOR1)) );
/* calculate buffer index */
tmphead = ( UART1_RxHead + 1) & UART_RX_BUFFER_MASK;
if ( tmphead == UART1_RxTail ) {
/* error: receive buffer overflow */
lastRxError = UART_BUFFER_OVERFLOW >> 8;
}else{
/* store new index */
UART1_RxHead = tmphead;
/* store received data in buffer */
UART1_RxBuf[tmphead] = data;
}
UART1_LastRxError = lastRxError;
}
ISR(UART1_TRANSMIT_INTERRUPT)
/*************************************************************************
Function: UART1 Data Register Empty interrupt
Purpose: called when the UART1 is ready to transmit the next byte
**************************************************************************/
{
unsigned char tmptail;
if ( UART1_TxHead != UART1_TxTail) {
/* calculate and store new buffer index */
tmptail = (UART1_TxTail + 1) & UART_TX_BUFFER_MASK;
UART1_TxTail = tmptail;
/* get one byte from buffer and write it to UART */
UART1_DATA = UART1_TxBuf[tmptail]; /* start transmission */
}else{
/* tx buffer empty, disable UDRE interrupt */
UART1_CONTROL &= ~_BV(UART1_UDRIE);
}
}
/*************************************************************************
Function: uart1_init()
Purpose: initialize UART1 and set baudrate
Input: baudrate using macro UART_BAUD_SELECT()
Returns: none
**************************************************************************/
void uart1_init(unsigned int baudrate)
{
UART1_TxHead = 0;
UART1_TxTail = 0;
UART1_RxHead = 0;
UART1_RxTail = 0;
/* Set baud rate */
if ( baudrate & 0x8000 )
{
UART1_STATUS = (1<<U2X1); //Enable 2x speed
baudrate &= ~0x8000;
}
UBRR1H = (unsigned char)(baudrate>>8);
UBRR1L = (unsigned char) baudrate;
/* Enable USART receiver and transmitter and receive complete interrupt */
UART1_CONTROL = _BV(RXCIE1)|(1<<RXEN1)|(1<<TXEN1);
/* Set frame format: asynchronous, 8data, no parity, 1stop bit */
#ifdef URSEL1
UCSR1C = (1<<URSEL1)|(3<<UCSZ10);
#else
UCSR1C = (3<<UCSZ10);
#endif
}/* uart_init */
/*************************************************************************
Function: uart1_getc()
Purpose: return byte from ringbuffer
Returns: lower byte: received byte from ringbuffer
higher byte: last receive error
**************************************************************************/
unsigned int uart1_getc(void)
{
unsigned char tmptail;
unsigned char data;
if ( UART1_RxHead == UART1_RxTail ) {
return UART_NO_DATA; /* no data available */
}
/* calculate /store buffer index */
tmptail = (UART1_RxTail + 1) & UART_RX_BUFFER_MASK;
UART1_RxTail = tmptail;
/* get data from receive buffer */
data = UART1_RxBuf[tmptail];
return (UART1_LastRxError << 8) + data;
}/* uart1_getc */
/*************************************************************************
Function: uart1_putc()
Purpose: write byte to ringbuffer for transmitting via UART
Input: byte to be transmitted
Returns: none
**************************************************************************/
void uart1_putc(unsigned char data)
{
unsigned char tmphead;
tmphead = (UART1_TxHead + 1) & UART_TX_BUFFER_MASK;
while ( tmphead == UART1_TxTail ){
;/* wait for free space in buffer */
}
UART1_TxBuf[tmphead] = data;
UART1_TxHead = tmphead;
/* enable UDRE interrupt */
UART1_CONTROL |= _BV(UART1_UDRIE);
}/* uart1_putc */
/*************************************************************************
Function: uart1_puts()
Purpose: transmit string to UART1
Input: string to be transmitted
Returns: none
**************************************************************************/
void uart1_puts(const char *s )
{
while (*s)
uart1_putc(*s++);
}/* uart1_puts */
/*************************************************************************
Function: uart1_puts_p()
Purpose: transmit string from program memory to UART1
Input: program memory string to be transmitted
Returns: none
**************************************************************************/
void uart1_puts_p(const char *progmem_s )
{
register char c;
while ( (c = pgm_read_byte(progmem_s++)) )
uart1_putc(c);
}/* uart1_puts_p */
#endif
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.