Add 100Hz timer

Use Timer 1 to generate a 100Hz timer interrupt

1 files changed, 80 insertions, 0 deletions

diff --git a/ao_timer.c b/ao_timer.c
new file mode 100644
index 00000000..7a81f32e
--- /dev/null
+++ b/ao_timer.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright © 2009 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"
+
+volatile __data uint16_t ao_time;
+
+void ao_timer_isr(void) interrupt 9
+{
+	++ao_time;
+	ao_wakeup(DATA_TO_XDATA(&ao_time));
+}
+
+uint16_t ao_time_atomic(void)
+{
+	uint8_t ret1;
+	uint16_t ret2;
+	
+	for (;;) {
+		ret1 = ao_time >> 8;
+		ret2 = ao_time;
+		if (ret1 == ((__xdata uint8_t *)(&ret2))[1])
+			break;
+	}
+	return ret2;
+}
+
+#define T1_CLOCK_DIVISOR	8	/* 24e6/8 = 3e6 */
+#define T1_SAMPLE_TIME		30000	/* 3e6/30000 = 100 */
+
+void
+ao_timer_init(void)
+{
+	/* NOTE:  This uses a timer only present on cc1111 architecture. */
+
+	/* disable timer 1 */
+	T1CTL = 0;
+
+	/* set the sample rate */
+	T1CC0H = T1_SAMPLE_TIME >> 8;
+	T1CC0L = T1_SAMPLE_TIME;
+
+	T1CCTL0 = T1CCTL_MODE_COMPARE;
+	T1CCTL1 = 0;
+	T1CCTL2 = 0;
+
+	/* clear timer value */
+	T1CNTL = 0;
+
+	/* enable overflow interrupt */
+	OVFIM = 1;
+	/* enable timer 1 interrupt */
+	T1IE = 1;
+
+	/* enable timer 1 in module mode, dividing by 8 */
+	T1CTL = T1CTL_MODE_MODULO | T1CTL_DIV_8;
+}
+
+void
+ao_delay(uint16_t ticks)
+{
+	uint16_t until = ao_time_atomic() + ticks;
+
+	while ((int16_t) (until - ao_time_atomic()) > 0)
+		ao_sleep(DATA_TO_XDATA(&ao_time));
+}