Place CPU in P0 state while idle

2 files changed, 22 insertions, 7 deletions

diff --git a/ao_task.c b/ao_task.c
index 81a71dda..b69f51ee 100644
--- a/ao_task.c
+++ b/ao_task.c
@@ -114,13 +114,23 @@ ao_yield(void) _naked
 	/* Find a task to run. If there isn't any runnable task,
 	 * this loop will run forever, which is just fine
 	 */
-	for (;;) {
-		++ao_cur_task_index;
-		if (ao_cur_task_index == ao_num_tasks)
-			ao_cur_task_index = 0;
-		ao_cur_task = ao_tasks[ao_cur_task_index];
-		if (ao_cur_task->wchan == NULL)
-			break;
+	{
+		__pdata uint8_t	ao_next_task_index = ao_cur_task_index;
+		for (;;) {
+			++ao_next_task_index;
+			if (ao_next_task_index == ao_num_tasks)
+				ao_next_task_index = 0;
+
+			ao_cur_task = ao_tasks[ao_next_task_index];
+			if (ao_cur_task->wchan == NULL) {
+				ao_cur_task_index = ao_next_task_index;
+				break;
+			}
+
+			/* Enter lower power mode when there isn't anything to do */
+			if (ao_next_task_index == ao_cur_task_index)
+				PCON = PCON_IDLE;
+		}
 	}
 
 	{
diff --git a/cc1111.h b/cc1111.h
index 10d446c0..2045c716 100644
--- a/cc1111.h
+++ b/cc1111.h
@@ -96,6 +96,11 @@ sfr at 0x9A IEN2;		/* Interrupt Enable 2 Register */
 #define SLEEP_MODE_PM3		(3 << 0)
 #define SLEEP_MODE_MASK		(3 << 0)
 
+/* PCON 0x87 */
+sfr at 0x87 PCON;		/* Power Mode Control Register */
+
+#define PCON_IDLE		(1 << 0)
+
 /*
  * TCON
  */