started on the firmware, added BOM

[nixiedisp] / fw / src / serial.c

diff --git a/fw/src/serial.c b/fw/src/serial.c
new file mode 100644 (file)
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);
+       }
+}