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 #if UART_TX_ENABLED
  55     /* store data */
  56     fifo_enqueue((fifo_t *)&global_uart.tx, data);
  57
  58     /* enable interrupt */
  59     _UCSRB_UART0 |= _BV(_UDRIE_UART0);
  60 #endif
  61 }
  62
  63 /** init the hardware uart */
  64 void uart_init(void)
  65 {
  66     #define BAUD CONFIG_SERIAL_BAUDRATE
  67     #include <util/setbaud.h>
  68
  69     /* set baud rate */
  70     _UBRRH_UART0 = UBRRH_VALUE;
  71     _UBRRL_UART0 = UBRRL_VALUE;
  72
  73     #if USE_2X
  74     _UCSRA_UART0 |= (1 << _U2X_UART0);
  75     #endif
  76
  77     /* set mode */
  78     _UCSRC_UART0 = UART_UCSRC;
  79
  80 #if UART_TX_ENABLED
  81     /* enable transmitter, receiver and receiver complete interrupt */
  82     _UCSRB_UART0 = _BV(_TXEN_UART0) | _BV(_RXEN_UART0) | _BV(_RXCIE_UART0);
  83     /* init tx fifo */
  84     fifo_init((fifo_t *)&global_uart.tx);
  85 #else
  86     /* enable receiver and receiver complete interrupt */
  87     _UCSRB_UART0 = _BV(_RXEN_UART0) | _BV(_RXCIE_UART0);
  88 #endif
  89
  90     /* init rx fifo */
  91     fifo_init((fifo_t *)&global_uart.rx);
  92 }
  93
  94
  95 /** interrupts*/
  96
  97 /** uart receive interrupt */
  98 ISR(_SIG_UART_RECV_UART0)
  99 {
 100
 101     /* store received data */
 102     fifo_enqueue((fifo_t *)&global_uart.rx, _UDR_UART0);
 103
 104 }
 105
 106 #if UART_TX_ENABLED
 107 /** uart data register empty interrupt */
 108 ISR(_SIG_UART_DATA_UART0)
 109 {
 110     /* load next byte to transfer */
 111     _UDR_UART0 = fifo_dequeue((fifo_t *)&global_uart.tx);
 112
 113     /* check if this interrupt is still needed */
 114     if ( fifo_fill((fifo_t *)&global_uart.tx) == 0) {
 115         /* disable this interrupt */
 116         _UCSRB_UART0 &= ~_BV(_UDRIE_UART0);
 117     }
 118 }
 119 #endif
 120
 121
 122 #endif