samples: nrf52: power_mgr: Demonstrate power state forcing

This commit extends the power_mgr sample in order to demonstrate
power state forcing using the sys_pm_force_power_state() API.

Signed-off-by: Piotr Zięcik <[email protected]>

Author: pizi-nordic

samples/boards/nrf52/power_mgr/README.rst

@@ -104,5 +104,9 @@ nRF52 core output
   --> Entering to SYS_POWER_STATE_CPU_LPS_2 state.
   --> Exited from SYS_POWER_STATE_CPU_LPS_2 state.
 
-  Press BUTTON1 to enter into Deep Sleep state. Press BUTTON2 to exit Deep Sleep state
-  --> Entering to SYS_POWER_STATE_DEEP_SLEEP state.
+  <-- Enabling SYS_POWER_STATE_CPU_LPS_1 state --->
+  <-- Forcing SYS_POWER_STATE_CPU_LPS_2 state --->
+
+  <-- App doing busy wait for 10 Sec -->
+
+  <-- App going to sleep for 10 Sec -->

samples/boards/nrf52/power_mgr/src/main.c

@@ -51,7 +51,7 @@ void main(void)
 	/*
 	 * Start the demo.
 	 */
-	for (int i = 1; i <= 6; i++) {
+	for (int i = 1; i <= 8; i++) {
 		unsigned int sleep_seconds;
 
 		switch (i) {
@@ -71,6 +71,16 @@ void main(void)
 			sys_pm_ctrl_disable_state(SYS_POWER_STATE_CPU_LPS_1);
 			break;
 
+		case 7:
+			printk("\n<-- Enabling %s state --->\n",
+				       STRINGIFY(SYS_POWER_STATE_CPU_LPS_1));
+			sys_pm_ctrl_enable_state(SYS_POWER_STATE_CPU_LPS_1);
+
+			printk("<-- Forcing %s state --->\n",
+				       STRINGIFY(SYS_POWER_STATE_CPU_LPS_2));
+			sys_pm_force_power_state(SYS_POWER_STATE_CPU_LPS_2);
+			break;
+
 		default:
 			/* Do nothing. */
 			break;
@@ -87,6 +97,11 @@ void main(void)
 		k_sleep(K_SECONDS(sleep_seconds));
 	}
 
+	/* Restore automatic power management. */
+	printk("\n<-- Forcing %s state --->\n",
+		       STRINGIFY(SYS_POWER_STATE_AUTO));
+	sys_pm_force_power_state(SYS_POWER_STATE_AUTO);
+
 	printk("\nPress BUTTON1 to enter into Deep Sleep state. "
 			"Press BUTTON2 to exit Deep Sleep state\n");
 	while (1) {