1 files changed, 129 insertions, 0 deletions

diff --git a/common/uart.c b/common/uart.c
new file mode 100644
index 000000000..c17649b08
--- /dev/null
+++ b/common/uart.c
@@ -0,0 +1,129 @@
+// TODO: Teensy support(ATMega32u4/AT90USB128)
+// Fixed for Arduino Duemilanove ATmega168p by Jun Wako
+/* UART Example for Teensy USB Development Board
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2009 PJRC.COM, LLC
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// Version 1.0: Initial Release
+// Version 1.1: Add support for Teensy 2.0, minor optimizations
+
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+#include "uart.h"
+
+// These buffers may be any size from 2 to 256 bytes.
+#define RX_BUFFER_SIZE 64
+#define TX_BUFFER_SIZE 40
+
+static volatile uint8_t tx_buffer[TX_BUFFER_SIZE];
+static volatile uint8_t tx_buffer_head;
+static volatile uint8_t tx_buffer_tail;
+static volatile uint8_t rx_buffer[RX_BUFFER_SIZE];
+static volatile uint8_t rx_buffer_head;
+static volatile uint8_t rx_buffer_tail;
+
+// Initialize the UART
+void uart_init(uint32_t baud)
+{
+        cli();
+        UBRR0 = (F_CPU / 4 / baud - 1) / 2;
+        UCSR0A = (1<<U2X0);
+        UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0);
+        UCSR0C = (1<<UCSZ01) | (1<<UCSZ00);
+        tx_buffer_head = tx_buffer_tail = 0;
+        rx_buffer_head = rx_buffer_tail = 0;
+        sei();
+}
+
+// Transmit a byte
+void uart_putchar(uint8_t c)
+{
+        uint8_t i;
+
+        i = tx_buffer_head + 1;
+        if (i >= TX_BUFFER_SIZE) i = 0;
+        while (tx_buffer_tail == i) ; // wait until space in buffer
+        //cli();
+        tx_buffer[i] = c;
+        tx_buffer_head = i;
+        UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0) | (1<<UDRIE0);
+        //sei();
+}
+
+// Receive a byte
+uint8_t uart_getchar(void)
+{
+        uint8_t c, i;
+
+        while (rx_buffer_head == rx_buffer_tail) ; // wait for character
+        i = rx_buffer_tail + 1;
+        if (i >= RX_BUFFER_SIZE) i = 0;
+        c = rx_buffer[i];
+        rx_buffer_tail = i;
+        return c;
+}
+
+// Return the number of bytes waiting in the receive buffer.
+// Call this before uart_getchar() to check if it will need
+// to wait for a byte to arrive.
+uint8_t uart_available(void)
+{
+        uint8_t head, tail;
+
+        head = rx_buffer_head;
+        tail = rx_buffer_tail;
+        if (head >= tail) return head - tail;
+        return RX_BUFFER_SIZE + head - tail;
+}
+
+// Transmit Interrupt
+ISR(USART_UDRE_vect)
+{
+        uint8_t i;
+
+        if (tx_buffer_head == tx_buffer_tail) {
+                // buffer is empty, disable transmit interrupt
+                UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0);
+        } else {
+                i = tx_buffer_tail + 1;
+                if (i >= TX_BUFFER_SIZE) i = 0;
+                UDR0 = tx_buffer[i];
+                tx_buffer_tail = i;
+        }
+}
+
+// Receive Interrupt
+ISR(USART_RX_vect)
+{
+        uint8_t c, i;
+
+        c = UDR0;
+        i = rx_buffer_head + 1;
+        if (i >= RX_BUFFER_SIZE) i = 0;
+        if (i != rx_buffer_tail) {
+                rx_buffer[i] = c;
+                rx_buffer_head = i;
+        }
+}
+