Mantis: play power off tune

To play a power off tune, I needed to convert the file to C++, so that I
could use the uORB::Publication.

The current implementation starts playing the power off sound but then
stops it as soon as the button is released.

The problem is mostly that we only get an interrupt when the button is
pressed or released but we don't seem to be able to poll it, at least
not in the current state.

boards/atl/mantis-edu/src/CMakeLists.txt

@@ -39,7 +39,7 @@ add_library(drivers_board
 	spi.cpp
 	timer_config.cpp
 	usb.c
-	pwr.c
+	pwr.cpp
 )
 add_dependencies(drivers_board arch_board_hw_info)
 

boards/atl/mantis-edu/src/pwr.cpp

@@ -53,6 +53,7 @@
 #include <nuttx/arch.h>
 
 #include <uORB/uORB.h>
+#include <uORB/Publication.hpp>
 #include <uORB/topics/led_control.h>
 #include <uORB/topics/tune_control.h>
 
@@ -116,13 +117,26 @@ int board_power_off(int status)
 
 static int board_button_irq(int irq, FAR void *context, FAR void *args)
 {
+	uORB::Publication<tune_control_s, tune_control_s::ORB_QUEUE_LENGTH> tune_control_pub{ORB_ID(tune_control)};
+
 	if (board_pwr_button_down()) {
 
 		led_on(BOARD_LED_RED);
 		clock_gettime(CLOCK_REALTIME, &time_down);
 		power_state_notification(PWR_BUTTON_DOWN);
 
+		tune_control_s tune_control{};
+		tune_control.volume = tune_control_s::VOLUME_LEVEL_DEFAULT - 20;
+		tune_control.tune_id = tune_control_s::TUNE_ID_POWER_OFF;
+		tune_control.timestamp = hrt_absolute_time();
+		tune_control_pub.publish(tune_control);
+
 	} else {
+		tune_control_s tune_control{};
+		tune_control.tune_override = true;
+		tune_control.timestamp = hrt_absolute_time();
+		tune_control_pub.publish(tune_control);
+
 		power_state_notification(PWR_BUTTON_UP);
 
 		led_off(BOARD_LED_RED);