avr/uart.h

   1 #ifndef UART_H
   2 #define UART_H
   3 /************************************************************************
   4 Title:    Interrupt UART library with receive/transmit circular buffers
   5 Author:   Peter Fleury <pfleury@gmx.ch>   http://jump.to/fleury
   6 Fiddled around with by: jaseg
   7 CAUTION! THIS FILE CURRENTLY ONLY WORKS WITH ATMega328p and similar devices because
   8 only for these I was keen to change the signal names to proper interrupt vectors
   9 File:     $Id: uart.h,v 1.8.2.1 2007/07/01 11:14:38 peter Exp $
  10 Software: AVR-GCC 4.1, AVR Libc 1.4
  11 Hardware: any AVR with built-in UART, tested on AT90S8515 & ATmega8 at 4 Mhz
  12 License:  GNU General Public License
  13 Usage:    see Doxygen manual
  14
  15 LICENSE:
  16     Copyright (C) 2006 Peter Fleury
  17
  18     This program is free software; you can redistribute it and/or modify
  19     it under the terms of the GNU General Public License as published by
  20     the Free Software Foundation; either version 2 of the License, or
  21     any later version.
  22
  23     This program is distributed in the hope that it will be useful,
  24     but WITHOUT ANY WARRANTY; without even the implied warranty of
  25     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26     GNU General Public License for more details.
  27
  28 ************************************************************************/
  29
  30 /**
  31  *  @defgroup pfleury_uart UART Library
  32  *  @code #include <uart.h> @endcode
  33  *
  34  *  @brief Interrupt UART library using the built-in UART with transmit and receive circular buffers.
  35  *
  36  *  This library can be used to transmit and receive data through the built in UART.
  37  *
  38  *  An interrupt is generated when the UART has finished transmitting or
  39  *  receiving a byte. The interrupt handling routines use circular buffers
  40  *  for buffering received and transmitted data.
  41  *
  42  *  The UART_RX_BUFFER_SIZE and UART_TX_BUFFER_SIZE constants define
  43  *  the size of the circular buffers in bytes. Note that these constants must be a power of 2.
  44  *  You may need to adapt this constants to your target and your application by adding
  45  *  CDEFS += -DUART_RX_BUFFER_SIZE=nn -DUART_RX_BUFFER_SIZE=nn to your Makefile.
  46  *
  47  *  @note Based on Atmel Application Note AVR306
  48  *  @author Peter Fleury pfleury@gmx.ch  http://jump.to/fleury
  49  */
  50
  51 /**@{*/
  52
  53
  54 #if (__GNUC__ * 100 + __GNUC_MINOR__) < 304
  55 #error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"
  56 #endif
  57
  58 #include <avr/io.h>
  59
  60
  61 /*
  62 ** constants and macros
  63 */
  64
  65 /** @brief  UART Baudrate Expression
  66  *  @param  xtalcpu  system clock in Mhz, e.g. 4000000L for 4Mhz
  67  *  @param  baudrate baudrate in bps, e.g. 1200, 2400, 9600
  68  */
  69 #define UART_BAUD_SELECT(baudRate,xtalCpu) ((xtalCpu)/((baudRate)*16l)-1)
  70
  71 /** @brief  UART Baudrate Expression for ATmega double speed mode
  72  *  @param  xtalcpu  system clock in Mhz, e.g. 4000000L for 4Mhz
  73  *  @param  baudrate baudrate in bps, e.g. 1200, 2400, 9600
  74  */
  75 #define UART_BAUD_SELECT_DOUBLE_SPEED(baudRate,xtalCpu) (((xtalCpu)/((baudRate)*8l)-1)|0x8000)
  76
  77
  78 /** Size of the circular receive buffer, must be power of 2 */
  79 #ifndef UART_RX_BUFFER_SIZE
  80 #define UART_RX_BUFFER_SIZE 32
  81 #endif
  82 /** Size of the circular transmit buffer, must be power of 2 */
  83 #ifndef UART_TX_BUFFER_SIZE
  84 #define UART_TX_BUFFER_SIZE 32
  85 #endif
  86
  87 /* test if the size of the circular buffers fits into SRAM */
  88 #if ( (UART_RX_BUFFER_SIZE+UART_TX_BUFFER_SIZE) >= (RAMEND-0x60 ) )
  89 #error "size of UART_RX_BUFFER_SIZE + UART_TX_BUFFER_SIZE larger than size of SRAM"
  90 #endif
  91
  92 /*
  93 ** high byte error return code of uart_getc()
  94 */
  95 #define UART_FRAME_ERROR      0x0800              /* Framing Error by UART       */
  96 #define UART_OVERRUN_ERROR    0x0400              /* Overrun condition by UART   */
  97 #define UART_BUFFER_OVERFLOW  0x0200              /* receive ringbuffer overflow */
  98 #define UART_NO_DATA          0x0100              /* no receive data available   */
  99
 100
 101 /*
 102 ** function prototypes
 103 */
 104
 105 /**
 106    @brief   Initialize UART and set baudrate
 107    @param   baudrate Specify baudrate using macro UART_BAUD_SELECT()
 108    @return  none
 109 */
 110 extern void uart_init(unsigned int baudrate);
 111
 112
 113 /**
 114  *  @brief   Get received byte from ringbuffer
 115  *
 116  * Returns in the lower byte the received character and in the
 117  * higher byte the last receive error.
 118  * UART_NO_DATA is returned when no data is available.
 119  *
 120  *  @param   void
 121  *  @return  lower byte:  received byte from ringbuffer
 122  *  @return  higher byte: last receive status
 123  *           - \b 0 successfully received data from UART
 124  *           - \b UART_NO_DATA
 125  *             <br>no receive data available
 126  *           - \b UART_BUFFER_OVERFLOW
 127  *             <br>Receive ringbuffer overflow.
 128  *             We are not reading the receive buffer fast enough,
 129  *             one or more received character have been dropped
 130  *           - \b UART_OVERRUN_ERROR
 131  *             <br>Overrun condition by UART.
 132  *             A character already present in the UART UDR register was
 133  *             not read by the interrupt handler before the next character arrived,
 134  *             one or more received characters have been dropped.
 135  *           - \b UART_FRAME_ERROR
 136  *             <br>Framing Error by UART
 137  */
 138 extern unsigned int uart_getc(void);
 139
 140
 141 /**
 142  *  @brief   Put byte to ringbuffer for transmitting via UART
 143  *  @param   data byte to be transmitted
 144  *  @return  none
 145  */
 146 extern void uart_putc(unsigned char data);
 147
 148 extern void uart_putc_nonblocking(unsigned char data);
 149
 150 /**
 151  *  @brief   Put string to ringbuffer for transmitting via UART
 152  *
 153  *  The string is buffered by the uart library in a circular buffer
 154  *  and one character at a time is transmitted to the UART using interrupts.
 155  *  Blocks if it can not write the whole string into the circular buffer.
 156  *
 157  *  @param   s string to be transmitted
 158  *  @return  none
 159  */
 160 extern void uart_puts(const char *s );
 161
 162
 163 /**
 164  * @brief    Put string from program memory to ringbuffer for transmitting via UART.
 165  *
 166  * The string is buffered by the uart library in a circular buffer
 167  * and one character at a time is transmitted to the UART using interrupts.
 168  * Blocks if it can not write the whole string into the circular buffer.
 169  *
 170  * @param    s program memory string to be transmitted
 171  * @return   none
 172  * @see      uart_puts_P
 173  */
 174 extern void uart_puts_p(const char *s );
 175
 176 /**
 177  * @brief    Macro to automatically put a string constant into program memory
 178  */
 179 #define uart_puts_P(__s)       uart_puts_p(PSTR(__s))
 180
 181 /**@}*/
 182
 183
 184 #endif // UART_H
 185