cdc_acm_check:Prevent USB disconect on param save

If the hardware support RESET lockout that has nArmed ANDed with VBUS
   vbus_sense may drop during a param save which uses
   BOARD_INDICATE_EXTERNAL_LOCKOUT_STATE to prevent external resets
   while writing the params.  If we are not armed and nARMRED is low
   we are in such a lock out so ignore changes on VBUS_SENSE during this
   time.

boards/nxp/fmurt1062-v1/src/board_config.h

@@ -228,6 +228,8 @@
 #define GPIO_nARMED          /* GPIO_SD_B1_01 GPIO3_IO1 */ (GPIO_PORT3 | GPIO_PIN1 | GPIO_OUTPUT | GPIO_OUTPUT_ZERO | nARMED_OUTPUT_IOMUX)
 
 #define BOARD_INDICATE_EXTERNAL_LOCKOUT_STATE(enabled)  px4_arch_configgpio((enabled) ? GPIO_nARMED : GPIO_nARMED_INIT)
+#define BOARD_GET_EXTERNAL_LOCKOUT_STATE() px4_arch_gpioread(GPIO_nARMED)
+
 
 /* PWM
  */

boards/px4/fmu-v5/src/board_config.h

@@ -212,6 +212,7 @@
 #define GPIO_nARMED          /* PI0 */  (GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_CLEAR|GPIO_PORTI|GPIO_PIN0)
 
 #define BOARD_INDICATE_EXTERNAL_LOCKOUT_STATE(enabled)  px4_arch_configgpio((enabled) ? GPIO_nARMED : GPIO_nARMED_INIT)
+#define BOARD_GET_EXTERNAL_LOCKOUT_STATE() px4_arch_gpioread(GPIO_nARMED)
 
 /* PWM
  */

boards/px4/fmu-v5x/src/board_config.h

@@ -213,6 +213,7 @@
 
 #if !defined(TRACE_PINS)
 #  define BOARD_INDICATE_EXTERNAL_LOCKOUT_STATE(enabled)  px4_arch_configgpio((enabled) ? GPIO_nARMED : GPIO_nARMED_INIT)
+#  define BOARD_GET_EXTERNAL_LOCKOUT_STATE() px4_arch_gpioread(GPIO_nARMED)
 #endif
 /* PWM
  */

boards/px4/fmu-v6x/src/board_config.h

@@ -229,6 +229,7 @@
 #define GPIO_nARMED_INIT     /* PE6 */  (GPIO_INPUT|GPIO_PULLUP|GPIO_PORTE|GPIO_PIN6)
 #define GPIO_nARMED          /* PE6 */  (GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_CLEAR|GPIO_PORTE|GPIO_PIN6)
 #define BOARD_INDICATE_EXTERNAL_LOCKOUT_STATE(enabled)  px4_arch_configgpio((enabled) ? GPIO_nARMED : GPIO_nARMED_INIT)
+#define BOARD_GET_EXTERNAL_LOCKOUT_STATE() px4_arch_gpioread(GPIO_nARMED)
 #endif
 
 

platforms/nuttx/src/px4/common/cdc_acm_check.cpp

@@ -87,9 +87,26 @@ static void mavlink_usb_check(void *arg)
 	uORB::SubscriptionData<actuator_armed_s> actuator_armed_sub{ORB_ID(actuator_armed)};
 
 	const bool armed = actuator_armed_sub.get().armed;
-	const bool vbus_present = (board_read_VBUS_state() == PX4_OK);
+	bool vbus_present = (board_read_VBUS_state() == PX4_OK);
+	bool locked_out = false;
+
+	// If the hardware support RESET lockout that has nArmed ANDed with VBUS
+	// vbus_sense may drop during a param save which uses
+	// BOARD_INDICATE_EXTERNAL_LOCKOUT_STATE to prevent external resets
+	// while writing the params.  If we are not armed and nARMRED is low
+	// we are in such a lock out so ignore changes on VBUS_SENSE during this
+	// time.
+#if defined(BOARD_GET_EXTERNAL_LOCKOUT_STATE)
+	locked_out = BOARD_GET_EXTERNAL_LOCKOUT_STATE() == 0;
+
+	if (locked_out) {
+		vbus_present = vbus_present_prev;
+	}
+
+#endif
+
 
-	if (!armed) {
+	if (!armed && !locked_out) {
 		switch (usb_auto_start_state) {
 		case UsbAutoStartState::disconnected:
 			if (vbus_present && vbus_present_prev) {