X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=nixiedisp;a=blobdiff_plain;f=fw%2Fsrc%2Fserial.c;fp=fw%2Fsrc%2Fserial.c;h=3ca641a020c4fd78c51b8a26fea55e9a7093bc41;hp=0000000000000000000000000000000000000000;hb=ed24a7090a6cae59e1f877e61c20e62fda31ed4a;hpb=4b91815bc8db814e32e39cbca5dd09338a5b8234

diff --git a/fw/src/serial.c b/fw/src/serial.c
new file mode 100644
index 0000000..3ca641a
--- /dev/null
+++ b/fw/src/serial.c
@@ -0,0 +1,103 @@
+#ifndef F_CPU
+#ifdef XTAL
+#define F_CPU	XTAL
+#else
+#warning "compiled for 1mhz internal rc osc. serial comms won't work"
+#define F_CPU	1000000
+#endif
+#endif
+
+#include <stdio.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include <avr/power.h>
+
+static int uart_send_char(char c, FILE *fp);
+static int uart_get_char(FILE *fp);
+
+#define BUF_SZ	16
+#define BUF_IDX_MASK	(BUF_SZ - 1)
+#define NEXT_IDX(x)	(((x) + 1) & BUF_IDX_MASK)
+static char outbuf[BUF_SZ];
+static volatile unsigned char out_rd, out_wr;
+static char inbuf[BUF_SZ];
+static volatile unsigned char in_rd, in_wr;
+
+static FILE std_stream = FDEV_SETUP_STREAM(uart_send_char, uart_get_char, _FDEV_SETUP_RW);
+
+
+
+void init_serial(long baud)
+{
+	unsigned int ubrr_val = F_CPU / 16 / baud - 1;
+
+	power_usart0_enable();
+
+	/* set baud generator timer reset value */
+	UBRR0H = (unsigned char)(ubrr_val >> 8);
+	UBRR0L = (unsigned char)ubrr_val;
+
+	/* enable rx/tx and recv interrupt */
+	UCSR0B = (1 << RXEN0) | (1 << TXEN0) | (1 << RXCIE0);
+	/* set frame format: 8n1 */
+	UCSR0C = 3 << UCSZ00;
+
+	stdin = stdout = stderr = &std_stream;
+}
+
+int have_input(void)
+{
+	return in_wr != in_rd;
+}
+
+static int uart_send_char(char c, FILE *fp)
+{
+	/*int next;*/
+	if(c == '\n') uart_send_char('\r', fp);
+
+	while((UCSR0A & (1 << UDRE0)) == 0);
+	UDR0 = (unsigned char)c;
+#if 0
+	next = NEXT_IDX(out_wr);
+	while(next == out_rd);
+
+	outbuf[out_wr] = c;
+	out_wr = next;
+
+	/* enable the Tx data register empty interrupt */
+	UCSR0B |= 1 << UDRIE0;
+#endif
+	return 0;
+}
+
+static int uart_get_char(FILE *fp)
+{
+	char c;
+
+	while(in_rd == in_wr);
+
+	c = inbuf[in_rd];
+	in_rd = NEXT_IDX(in_rd);
+	return c;
+}
+
+ISR(USART_RX_vect)
+{
+	char c = UDR0;
+
+	inbuf[in_wr] = c;
+	in_wr = NEXT_IDX(in_wr);
+}
+
+/* USART Tx data register empty (can send more data) */
+ISR(USART_UDRE_vect)
+{
+	if(out_rd != out_wr) {
+		UDR0 = outbuf[out_rd];
+		out_rd = NEXT_IDX(out_rd);
+	} else {
+		/* no more data to send for now, disable the interrupt */
+		UCSR0B &= ~(1 << UDRIE0);
+	}
+}