drivers/rc_input: RC_INPUT_PROTO parameter minimal implementation (#19539)

Co-authored-by: chris1seto <chris12892@gmail.com>

Co-authored-by: chris1seto <chris12892@gmail.com>

src/drivers/rc_input/RCInput.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (c) 2012-2021 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2022 PX4 Development Team. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -63,6 +63,10 @@ RCInput::RCInput(const char *device) :
 		strncpy(_device, device, sizeof(_device) - 1);
 		_device[sizeof(_device) - 1] = '\0';
 	}
+
+	if ((_param_rc_input_proto.get() >= 0) && (_param_rc_input_proto.get() <= RC_SCAN::RC_SCAN_GHST)) {
+		_rc_scan_state = static_cast<RC_SCAN>(_param_rc_input_proto.get());
+	}
 }
 
 RCInput::~RCInput()
@@ -251,9 +255,21 @@ RCInput::fill_rc_in(uint16_t raw_rc_count_local,
 
 void RCInput::set_rc_scan_state(RC_SCAN newState)
 {
-	PX4_DEBUG("RCscan: %s failed, trying %s", RCInput::RC_SCAN_STRING[_rc_scan_state], RCInput::RC_SCAN_STRING[newState]);
+	if ((_param_rc_input_proto.get() > RC_SCAN::RC_SCAN_NONE)
+	    && (_param_rc_input_proto.get() <= RC_SCAN::RC_SCAN_GHST)) {
+
+		_rc_scan_state = static_cast<RC_SCAN>(_param_rc_input_proto.get());
+
+	} else if (_param_rc_input_proto.get() < 0) {
+		// only auto change if RC_INPUT_PROTO set to auto (-1)
+		PX4_DEBUG("RCscan: %s failed, trying %s", RCInput::RC_SCAN_STRING[_rc_scan_state], RCInput::RC_SCAN_STRING[newState]);
+		_rc_scan_state = newState;
+
+	} else {
+		_rc_scan_state = RC_SCAN::RC_SCAN_NONE;
+	}
+
 	_rc_scan_begin = 0;
-	_rc_scan_state = newState;
 	_rc_scan_locked = false;
 
 	_report_lock = true;
@@ -419,6 +435,10 @@ void RCInput::Run()
 		}
 
 		switch (_rc_scan_state) {
+		case RC_SCAN_NONE:
+			// do nothing
+			break;
+
 		case RC_SCAN_SBUS:
 			if (_rc_scan_begin == 0) {
 				_rc_scan_begin = cycle_timestamp;
@@ -737,6 +757,12 @@ void RCInput::Run()
 		if (_report_lock && _rc_scan_locked) {
 			_report_lock = false;
 			PX4_INFO("RC scan: %s RC input locked", RC_SCAN_STRING[_rc_scan_state]);
+
+			if (!_armed && (_param_rc_input_proto.get() < 0)) {
+				// RC_INPUT_PROTO auto => locked selection
+				_param_rc_input_proto.set(_rc_scan_state);
+				_param_rc_input_proto.commit();
+			}
 		}
 	}
 }
@@ -823,6 +849,9 @@ int RCInput::print_status()
 
 	if (_rc_scan_locked) {
 		switch (_rc_scan_state) {
+		case RC_SCAN_NONE:
+			break;
+
 		case RC_SCAN_CRSF:
 			PX4_INFO("CRSF Telemetry: %s", _crsf_telemetry ? "yes" : "no");
 			break;

src/drivers/rc_input/RCInput.hpp

@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (c) 2012-2019, 2021 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2022 PX4 Development Team. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -91,21 +91,23 @@ public:
 private:
 
 	enum RC_SCAN {
-		RC_SCAN_PPM = 0,
+		RC_SCAN_NONE = 0,
-		RC_SCAN_SBUS,
+		RC_SCAN_PPM  = 1,
-		RC_SCAN_DSM,
+		RC_SCAN_SBUS = 2,
-		RC_SCAN_SUMD,
+		RC_SCAN_DSM  = 3,
-		RC_SCAN_ST24,
+		RC_SCAN_ST24 = 5,
-		RC_SCAN_CRSF,
+		RC_SCAN_SUMD = 4,
-		RC_SCAN_GHST
+		RC_SCAN_CRSF = 6,
+		RC_SCAN_GHST = 7,
 	} _rc_scan_state{RC_SCAN_SBUS};
 
-	static constexpr char const *RC_SCAN_STRING[7] {
+	static constexpr char const *RC_SCAN_STRING[] {
+		"None",
 		"PPM",
 		"SBUS",
 		"DSM",
-		"SUMD",
 		"ST24",
+		"SUMD",
 		"CRSF",
 		"GHST"
 	};
@@ -168,6 +170,7 @@ private:
 	DEFINE_PARAMETERS(
 		(ParamInt<px4::params::RC_RSSI_PWM_CHAN>) _param_rc_rssi_pwm_chan,
 		(ParamInt<px4::params::RC_RSSI_PWM_MIN>) _param_rc_rssi_pwm_min,
-		(ParamInt<px4::params::RC_RSSI_PWM_MAX>) _param_rc_rssi_pwm_max
+		(ParamInt<px4::params::RC_RSSI_PWM_MAX>) _param_rc_rssi_pwm_max,
+		(ParamInt<px4::params::RC_INPUT_PROTO>) _param_rc_input_proto
 	)
 };

src/drivers/rc_input/module.yaml

@@ -1,4 +1,28 @@
 module_name: RC Input Driver
+parameters:
+    - group: RC Input
+      definitions:
+        RC_INPUT_PROTO:
+            description:
+                short: RC input protocol
+                long: |
+                    Select your RC input protocol or auto to scan.
+            category: System
+            type: enum
+            values:
+                -1: Auto
+                0: None
+                1: PPM
+                2: SBUS
+                3: DSM
+                4: ST24
+                5: SUMD
+                6: CRSF
+                7: GHST
+            min: -1
+            max: 7
+            default: -1
+
 serial_config:
     - command: set RC_INPUT_ARGS "-d ${SERIAL_DEV}"
       port_config_param: