Add UART library.

tpic6b595_spi/uart/uart.c

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2011 Mika Tuupola
+ *
+ * Licensed under the MIT license:
+ *   http://www.opensource.org/licenses/mit-license.php
+ *
+ */
+ 
+#include <avr/io.h>
+#include <stdio.h>
+
+#ifndef F_CPU
+#define F_CPU 16000000UL
+#endif
+
+#ifndef BAUD
+#define BAUD 9600
+#endif
+#include <util/setbaud.h>
+
+/* http://www.cs.mun.ca/~rod/Winter2007/4723/notes/serial/serial.html */
+
+#if defined (__AVR_ATmega32U4__)
+void uart_init(void) {
+    UBRR1H = UBRRH_VALUE;
+    UBRR1L = UBRRL_VALUE;
+    
+#if USE_2X
+    UCSR1A |= _BV(U2X1);
+#else
+    UCSR1A &= ~(_BV(U2X1));
+#endif
+
+    UCSR1C = _BV(UCSZ11) | _BV(UCSZ10); /* 8-bit data */ 
+    UCSR1B = _BV(RXEN1) | _BV(TXEN1);   /* Enable RX and TX */    
+}
+#else
+void uart_init(void) {
+    UBRR0H = UBRRH_VALUE;
+    UBRR0L = UBRRL_VALUE;
+    
+#if USE_2X
+    UCSR0A |= _BV(U2X0);
+#else
+    UCSR0A &= ~(_BV(U2X0));
+#endif
+
+    UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); /* 8-bit data */ 
+    UCSR0B = _BV(RXEN0) | _BV(TXEN0);   /* Enable RX and TX */    
+}
+#endif
+
+void uart_putchar(char c, FILE *stream) {
+    if (c == '\n') {
+        uart_putchar('\r', stream);
+    }
+#if defined (__AVR_ATmega32U4__)
+    loop_until_bit_is_set(UCSR1A, UDRE1);
+    UDR1 = c;
+#else
+    loop_until_bit_is_set(UCSR0A, UDRE0);
+    UDR0 = c;
+#endif
+}
+
+char uart_getchar(FILE *stream) {
+#if defined (__AVR_ATmega32U4__)
+    loop_until_bit_is_set(UCSR1A, RXC1);
+    return UDR1;
+#else
+    loop_until_bit_is_set(UCSR0A, RXC0);
+    return UDR0;
+#endif
+}

tpic6b595_spi/uart/uart.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright 2011 Mika Tuupola
+ *
+ * Licensed under the MIT license:
+ *   http://www.opensource.org/licenses/mit-license.php
+ *
+ */
+ 
+void uart_putchar(char c, FILE *stream);
+char uart_getchar(FILE *stream);
+
+void uart_init(void);
+
+/* http://www.ermicro.com/blog/?p=325 */
+
+FILE uart_output = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);
+FILE uart_input = FDEV_SETUP_STREAM(NULL, uart_getchar, _FDEV_SETUP_READ);

tpic6b595_spi/uart/uart_async.c

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2011 Mika Tuupola
+ *
+ * Licensed under the MIT license:
+ *   http://www.opensource.org/licenses/mit-license.php
+ *
+ */
+
+/* Based on Atmel Application Note AVR 306 */
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <stdio.h>
+
+#ifndef BAUD
+#define BAUD 9600
+#endif
+#include <util/setbaud.h>
+
+#ifndef UART_RX_BUFFER_SIZE
+#define UART_RX_BUFFER_SIZE 64
+#endif
+
+#ifndef UART_TX_BUFFER_SIZE
+#define UART_TX_BUFFER_SIZE 64
+#endif
+
+struct tx_ring {
+    int buffer[UART_TX_BUFFER_SIZE];
+    int start;
+    int end;
+};
+
+struct rx_ring {
+    int buffer[UART_RX_BUFFER_SIZE];
+    int start;
+    int end;
+};
+
+static struct tx_ring tx_buffer;
+static struct rx_ring rx_buffer;
+
+/* http://www.cs.mun.ca/~rod/Winter2007/4723/notes/serial/serial.html */
+
+void uart_init(void) {
+    
+    tx_buffer.start = 0;
+    tx_buffer.end   = 0;
+
+    rx_buffer.start = 0;
+    rx_buffer.end   = 0;
+    
+    UBRR0H = UBRRH_VALUE;
+    UBRR0L = UBRRL_VALUE;
+
+    UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); /* 8-bit data */ 
+    UCSR0B = _BV(RXEN0) | _BV(TXEN0);   /* Enable RX and TX */  
+    
+    sei();  
+}
+
+
+//int uart_putchar(char c, FILE *stream) {
+void uart_putchar(char c, FILE *stream) {
+    if (c == '\n') {
+        uart_putchar('\r', stream);
+    }
+    
+    int write_pointer = (tx_buffer.end + 1) % UART_TX_BUFFER_SIZE;
+    
+    if (write_pointer != tx_buffer.start){
+        tx_buffer.buffer[tx_buffer.end] = c;
+        tx_buffer.end = write_pointer;
+        
+        /* Data available. Enable the transmit interrupt for serial port 0. */
+        UCSR0B |= _BV(UDRIE0);  
+    }
+    
+    //return 0;
+}
+
+char uart_getchar(FILE *stream) {
+    int read_pointer = (rx_buffer.start + 1) % UART_RX_BUFFER_SIZE;
+    
+    rx_buffer.start = read_pointer;
+    return rx_buffer.buffer[read_pointer];
+}
+
+ISR(USART_RX_vect) {
+    int write_pointer = (rx_buffer.end + 1) % UART_RX_BUFFER_SIZE;
+
+    /* Add next byte to ringbuffer if it has space available. */
+    if (write_pointer != rx_buffer.start){
+        rx_buffer.buffer[rx_buffer.end] = UDR0;
+        rx_buffer.end = write_pointer;
+    }
+}
+
+ISR(USART_UDRE_vect){
+    int read_pointer = (tx_buffer.start + 1) % UART_TX_BUFFER_SIZE;
+    
+    /* Transmit next byte if data available in ringbuffer. */
+    if (read_pointer != tx_buffer.end) {
+        UDR0 = tx_buffer.buffer[read_pointer];
+        tx_buffer.start = read_pointer;
+    } else {
+        /* Nothing to send. Disable the transmit interrupt for serial port 0. */
+        UCSR0B &= ~_BV(UDRIE0);
+    }
+}
+
+