1 files changed, 71 insertions, 0 deletions
diff --git a/src/attiny/ao_async.c b/src/attiny/ao_async.c
new file mode 100644
index 00000000..3556f54c
--- /dev/null
+++ b/src/attiny/ao_async.c
@@ -0,0 +1,71 @@
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+#include <ao_async.h>
+
+#define AO_ASYNC_BAUD	38400l
+#define AO_ASYNC_DELAY	(uint8_t) (1000000l / AO_ASYNC_BAUD)
+
+#define LED_PORT	PORTB
+
+void
+ao_async_start(void)
+{
+	LED_PORT |= (1 << AO_LED_SERIAL);
+}
+
+void
+ao_async_stop(void)
+{
+	LED_PORT &= ~(1 << AO_LED_SERIAL);
+}
+
+void
+ao_async_byte(uint8_t byte)
+{
+	uint8_t		b;
+	uint16_t	w;
+
+	/*    start           data           stop */
+	w = (0x000 << 0) | (byte << 1) | (0x001 << 9);
+
+	ao_arch_block_interrupts();
+	for (b = 0; b < 10; b++) {
+		uint8_t	v = LED_PORT & ~(1 << AO_LED_SERIAL);
+		v |= (w & 1) << AO_LED_SERIAL;
+		LED_PORT = v;
+		w >>= 1;
+
+		/* Carefully timed to hit around 9600 baud */
+		asm volatile ("nop");
+		asm volatile ("nop");
+
+		asm volatile ("nop");
+		asm volatile ("nop");
+		asm volatile ("nop");
+		asm volatile ("nop");
+		asm volatile ("nop");
+
+		asm volatile ("nop");
+		asm volatile ("nop");
+		asm volatile ("nop");
+		asm volatile ("nop");
+		asm volatile ("nop");
+	}
+	ao_arch_release_interrupts();
+}