git.zerfleddert.de Git - fnordlicht-mini/blob - firmware/fnordlicht-controller/uart.c

   1 /* vim:ts=4 sts=4 et tw=80
   2  *
   3  *         fnordlicht firmware
   4  *
   5  *    for additional information please
   6  *    see http://lochraster.org/fnordlichtmini
   7  *
   8  * (c) by Alexander Neumann <alexander@bumpern.de>
   9  *     Lars Noschinski <lars@public.noschinski.de>
  10  *
  11  * This program is free software: you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License version 3 as published by
  13  * the Free Software Foundation.
  14  *
  15  * This program is distributed in the hope that it will be useful, but WITHOUT
  16  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  18  * more details.
  19  *
  20  * You should have received a copy of the GNU General Public License along with
  21  * this program.  If not, see <http://www.gnu.org/licenses/>.
  22  */
  23
  24 #include "globals.h"
  25
  26 #if CONFIG_SERIAL
  27
  28 #include "../common/io.h"
  29 #include <avr/interrupt.h>
  30
  31 #include "globals.h"
  32 #include "../common/common.h"
  33 #include "fifo.h"
  34 #include "uart.h"
  35
  36 /* define uart mode (8N1) */
  37 #if defined(__AVR_ATmega8__)
  38 /* in atmega8, we need a special switching bit
  39  * for addressing UCSRC */
  40 #define UART_UCSRC _BV(URSEL) | _BV(UCSZ0) | _BV(UCSZ1)
  41
  42 #elif defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)
  43 /* in atmega88, this isn't needed any more */
  44 #define UART_UCSRC _BV(_UCSZ0_UART0) | _BV(_UCSZ1_UART0)
  45 #endif
  46
  47 /* global variables */
  48 volatile struct global_uart_t global_uart;
  49
  50 /** output one character */
  51 void uart_putc(uint8_t data)
  52 {
  53     /* store data */
  54     fifo_enqueue((fifo_t *)&global_uart.tx, data);
  55
  56     /* enable interrupt */
  57     _UCSRB_UART0 |= _BV(_UDRIE_UART0);
  58 }
  59
  60 /** init the hardware uart */
  61 void uart_init(void)
  62 {
  63     #define BAUD CONFIG_SERIAL_BAUDRATE
  64     #include <util/setbaud.h>
  65
  66     /* set baud rate */
  67     _UBRRH_UART0 = UBRRH_VALUE;
  68     _UBRRL_UART0 = UBRRL_VALUE;
  69
  70     #if USE_2X
  71     _UCSRA_UART0 |= (1 << _U2X_UART0);
  72     #endif
  73
  74     /* set mode */
  75     _UCSRC_UART0 = UART_UCSRC;
  76
  77     /* enable transmitter, receiver and receiver complete interrupt */
  78     _UCSRB_UART0 = _BV(_TXEN_UART0) | _BV(_RXEN_UART0) | _BV(_RXCIE_UART0);
  79
  80     /* init fifos */
  81     fifo_init((fifo_t *)&global_uart.rx);
  82     fifo_init((fifo_t *)&global_uart.tx);
  83 }
  84
  85
  86 /** interrupts*/
  87
  88 /** uart receive interrupt */
  89 ISR(_SIG_UART_RECV_UART0)
  90 {
  91
  92     /* store received data */
  93     fifo_enqueue((fifo_t *)&global_uart.rx, _UDR_UART0);
  94
  95 }
  96
  97 /** uart data register empty interrupt */
  98 ISR(_SIG_UART_DATA_UART0)
  99 {
 100
 101     /* load next byte to transfer */
 102     _UDR_UART0 = fifo_dequeue((fifo_t *)&global_uart.tx);
 103
 104     /* check if this interrupt is still needed */
 105     if ( fifo_fill((fifo_t *)&global_uart.tx) == 0) {
 106         /* disable this interrupt */
 107         _UCSRB_UART0 &= ~_BV(_UDRIE_UART0);
 108     }
 109
 110 }
 111
 112
 113 #endif