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[fnordlicht-mini] / 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
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