uavcan: more efficient calculation of esc.RawCommand.cmd array size

src/drivers/uavcan/actuators/esc.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2014 PX4 Development Team. All rights reserved.
+ *   Copyright (C) 2014-2025 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
@@ -74,20 +74,13 @@ UavcanEscController::init()
 		_uavcan_pub_raw_cmd.getTransferSender().setIfaceMask(iface_mask);
 	}
 
-	char param_name[17];
-
-	for (unsigned i = 0; i < MAX_ACTUATORS; ++i) {
-		snprintf(param_name, sizeof(param_name), "UAVCAN_EC_FUNC%d", i + 1);
-		_param_handles[i] = param_find(param_name);
-	}
-
 	_initialized = true;
 
 	return res;
 }
 
 void
-UavcanEscController::update_outputs(uint16_t outputs[MAX_ACTUATORS], unsigned total_outputs)
+UavcanEscController::update_outputs(uint16_t outputs[MAX_ACTUATORS], uint8_t output_array_size)
 {
 	// TODO: configurable rate limit
 	const auto timestamp = _node.getMonotonicTime();
@@ -100,26 +93,10 @@ UavcanEscController::update_outputs(uint16_t outputs[MAX_ACTUATORS], unsigned to
 
 	uavcan::equipment::esc::RawCommand msg = {};
 
-	// directly output values from mixer
-	for (unsigned i = 0; i < total_outputs; i++) {
+	for (unsigned i = 0; i < output_array_size; i++) {
 		msg.cmd.push_back(static_cast<int>(outputs[i]));
 	}
 
-	// but only output as many channels as are configured
-	uint8_t min_size = 0;
-
-	for (int i = 0; i < MAX_ACTUATORS; i++) {
-		int32_t val = 0;
-
-		if (param_get(_param_handles[i], &val) == 0) {
-			if (val > 0) {
-				min_size = i + 1;
-			}
-		}
-	}
-
-	msg.cmd.resize(min_size);
-
 	_uavcan_pub_raw_cmd.broadcast(msg);
 }
 

src/drivers/uavcan/actuators/esc.hpp

@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2014 PX4 Development Team. All rights reserved.
+ *   Copyright (C) 2014-2025 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
@@ -71,7 +71,7 @@ public:
 
 	bool initialized() { return _initialized; };
 
-	void update_outputs(uint16_t outputs[MAX_ACTUATORS], unsigned total_outputs);
+	void update_outputs(uint16_t outputs[MAX_ACTUATORS], uint8_t output_array_size);
 
 	/**
 	 * Sets the number of rotors and enable timer
@@ -114,7 +114,4 @@ private:
 	uavcan::INode								&_node;
 	uavcan::Publisher<uavcan::equipment::esc::RawCommand>			_uavcan_pub_raw_cmd;
 	uavcan::Subscriber<uavcan::equipment::esc::Status, StatusCbBinder>	_uavcan_sub_status;
-
-
-	param_t _param_handles[MAX_ACTUATORS] {PARAM_INVALID};
 };

src/drivers/uavcan/uavcan_main.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (c) 2014-2022 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2014-2025 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
@@ -1082,7 +1082,19 @@ bool UavcanMixingInterfaceESC::updateOutputs(uint16_t outputs[MAX_ACTUATORS], un
 		unsigned num_control_groups_updated)
 {
 	if (_esc_controller.initialized()) {
-		_esc_controller.update_outputs(outputs, num_outputs);
+		// num_outputs is the maximum possible number of outputs (8)
+		// output_array_size adapts to the highest output index that is mapped (4 for a quad)
+		// this allows for sending less CAN frames depending on what output indices are mapped
+		uint8_t output_array_size = 0;
+
+		for (int i = MAX_ACTUATORS - 1; i >= 0; i--) {
+			if (mixingOutput().isFunctionSet(i)) {
+				output_array_size = i + 1;
+				break;
+			}
+		}
+
+		_esc_controller.update_outputs(outputs, output_array_size);
 	}
 
 	return true;