root / trunk / cardbox / rs485_int.c @ 206
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| 1 | 139 | kwoo | /********
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| 2 | * This file is part of Tooltron.
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| 3 | *
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| 4 | * Tooltron is free software: you can redistribute it and/or modify
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| 5 | * it under the terms of the Lesser GNU General Public License as published by
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| 6 | * the Free Software Foundation, either version 3 of the License, or
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| 7 | * (at your option) any later version.
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| 8 | *
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| 9 | * Tooltron is distributed in the hope that it will be useful,
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| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | * Lesser GNU General Public License for more details.
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| 13 | * You should have received a copy of the Lesser GNU General Public License
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| 14 | * along with Tooltron. If not, see <http://www.gnu.org/licenses/>.
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| 15 | *
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| 16 | * Copyright 2009 Kevin Woo <kwoo@2ndt.com>
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| 17 | *
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| 18 | ********/
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| 19 | 8 | kwoo | /** @file uart.c
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| 20 | *
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| 21 | * @brief Implements UART functionality in hardware
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| 22 | *
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| 23 | * @author Kevin Woo (kwoo)
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| 24 | */
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| 25 | |||
| 26 | #include "uart.h" |
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| 27 | 143 | bneuman | #include <util/delay.h> |
| 28 | 109 | kwoo | #include <stdint.h> |
| 29 | 8 | kwoo | |
| 30 | 109 | kwoo | uint8_t received_byte; //Byte received
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| 31 | uint8_t byte_ready; //New byte has been received
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| 32 | 8 | kwoo | |
| 33 | 109 | kwoo | void init_uart(uint16_t baud) {
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| 34 | // Set baud rate
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| 35 | UBRRH = (uint8_t)(baud>>8);
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| 36 | UBRRL = (uint8_t)baud; |
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| 37 | |||
| 38 | // Enable RX/TX and RX/TX Interrupt
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| 39 | 9 | kwoo | UCSRB = _BV(RXCIE) | _BV(RXEN) | _BV(TXCIE) | _BV(TXEN); |
| 40 | 8 | kwoo | |
| 41 | 109 | kwoo | // Enable the TXEN pin as output
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| 42 | DDRD |= TX_EN; |
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| 43 | |||
| 44 | // Initialize receive variables
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| 45 | byte_ready = 0;
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| 46 | received_byte = 0x0;
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| 47 | 8 | kwoo | } |
| 48 | |||
| 49 | 109 | kwoo | int8_t uart_get_byte(uint8_t *output_byte) {
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| 50 | 8 | kwoo | if (byte_ready) {
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| 51 | 109 | kwoo | byte_ready = 0;
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| 52 | 8 | kwoo | *output_byte = received_byte; |
| 53 | return 0; |
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| 54 | } else {
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| 55 | return -1; |
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| 56 | } |
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| 57 | } |
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| 58 | |||
| 59 | 109 | kwoo | void uart_send_byte(uint8_t data) {
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| 60 | 13 | kwoo | //Waits until current transmit is done
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| 61 | 109 | kwoo | while (!(UCSRA & _BV(UDRE)));
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| 62 | 13 | kwoo | |
| 63 | 109 | kwoo | // Enable writes and send
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| 64 | uart_toggle_transmit(UART_TX_ON); |
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| 65 | UDR = data; |
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| 66 | 9 | kwoo | return;
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| 67 | } |
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| 68 | |||
| 69 | 109 | kwoo | void uart_toggle_transmit(uint8_t state) {
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| 70 | 13 | kwoo | if (state == UART_TX_ON) {
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| 71 | 109 | kwoo | PORTD |= TX_EN; |
| 72 | 13 | kwoo | } else {
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| 73 | 109 | kwoo | PORTD &= ~TX_EN; |
| 74 | 13 | kwoo | } |
| 75 | } |
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| 76 | |||
| 77 | 109 | kwoo | ISR(USART_RX_vect) {
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| 78 | received_byte = UDR; |
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| 79 | 117 | kwoo | byte_ready = 1;
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| 80 | 8 | kwoo | } |
| 81 | 9 | kwoo | |
| 82 | 109 | kwoo | ISR(USART_TX_vect) {
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| 83 | // Re-enable reads
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| 84 | uart_toggle_transmit(UART_TX_OFF); |
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| 85 | 9 | kwoo | } |