git.zerfleddert.de Git - fnordlicht-mini/blob - firmware/fnordlicht-firmware/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 "pwm.h"
  34 #include "fifo.h"
  35 #include "uart.h"
  36
  37 /* define uart mode (8N1) */
  38 #if defined(__AVR_ATmega8__)
  39 /* in atmega8, we need a special switching bit
  40  * for addressing UCSRC */
  41 #define UART_UCSRC _BV(URSEL) | _BV(UCSZ0) | _BV(UCSZ1)
  42
  43 #elif defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__)
  44 /* in atmega88, this isn't needed any more */
  45 #define UART_UCSRC _BV(_UCSZ0_UART0) | _BV(_UCSZ1_UART0)
  46 #endif
  47
  48 /* global variables */
  49 volatile struct global_uart_t global_uart;
  50
  51 /** output one character */
  52 void uart_putc(uint8_t data)
  53 {
  54     /* store data */
  55     fifo_enqueue((fifo_t *)&global_uart.tx, data);
  56
  57     /* enable interrupt */
  58     _UCSRB_UART0 |= _BV(_UDRIE_UART0);
  59 }
  60
  61 /** init the hardware uart */
  62 void uart_init(void)
  63 {
  64     #define BAUD CONFIG_SERIAL_BAUDRATE
  65     #include <util/setbaud.h>
  66
  67     /* set baud rate */
  68     _UBRRH_UART0 = UBRRH_VALUE;
  69     _UBRRL_UART0 = UBRRL_VALUE;
  70
  71     #if USE_2X
  72     _UCSRA_UART0 |= (1 << _U2X_UART0);
  73     #endif
  74
  75     /* set mode */
  76     _UCSRC_UART0 = UART_UCSRC;
  77
  78     /* enable transmitter, receiver and receiver complete interrupt */
  79     _UCSRB_UART0 = _BV(_TXEN_UART0) | _BV(_RXEN_UART0) | _BV(_RXCIE_UART0);
  80
  81     /* init fifos */
  82     fifo_init((fifo_t *)&global_uart.rx);
  83     fifo_init((fifo_t *)&global_uart.tx);
  84 }
  85
  86
  87 /** interrupts*/
  88
  89 /** uart receive interrupt */
  90 ISR(_SIG_UART_RECV_UART0)
  91 {
  92
  93     /* store received data */
  94     fifo_enqueue((fifo_t *)&global_uart.rx, _UDR_UART0);
  95
  96 }
  97
  98 /** uart data register empty interrupt */
  99 ISR(_SIG_UART_DATA_UART0)
 100 {
 101
 102     /* load next byte to transfer */
 103     _UDR_UART0 = fifo_dequeue((fifo_t *)&global_uart.tx);
 104
 105     /* check if this interrupt is still needed */
 106     if ( fifo_fill((fifo_t *)&global_uart.tx) == 0) {
 107         /* disable this interrupt */
 108         _UCSRB_UART0 &= ~_BV(_UDRIE_UART0);
 109     }
 110
 111 }
 112
 113
 114 #endif