engineering

MAVLink

MAVLink is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand MAVLink rather than just read about it. In short: MAVLink or Micro Air Vehicle Link is a protocol for communicating with small unmanned vehicle. It is designed as a header-only message marshalling library.

Key takeaways

MAVLink belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MAVLink to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MAVLink from memory before moving on to harder problems.

Reference excerpt

MAVLink or Micro Air Vehicle Link is a protocol for communicating with small unmanned vehicle. It is designed as a header-only message marshalling library. MAVLink was first released early 2009 by Lorenz Meier under the terms of the GNU Lesser General Public License (LGPL).

Applications It is used mostly for communication between a Ground Control Station (GCS) and unmanned vehicles, and in the inter-communication of the subsystem of the vehicle. It can be used to transmit the orientation of the vehicle, its GPS location and speed.

Packet structure In version 1.0 the packet structure is the following:

After Version 2, the packet structure was expanded into the following:

CRC field To ensure message integrity, a cyclic redundancy check (CRC) is calculated for each message up to the last two bytes. Another function of the CRC field is to ensure the sender and receiver both agree on the message that is being transferred. It is computed using an ITU X.25/SAE AS-4 hash of the bytes in the packet, excluding the Start-of-Frame indicator (so 6+n+1 bytes are evaluated, and the extra +1 is the seed value). Additionally a seed value is appended to the end of the data when computing the CRC. The seed is generated with each new message set of the protocol, and it is hashed in a similar way as the packets from each message specification. Systems using the MAVLink protocol can use a precomputed array for this purpose. The CRC algorithm of MAVLink has been implemented in many languages, including Python and Java.

Messages The payloads from the packets described above are MAVLink messages. Each message is identifiable by the ID field on the packet, and the payload contains the data from the message. An XML document in the MAVlink source has the definition of the data stored in this payload. Below is the message with ID 24 extracted from the XML document.

Note: The XML document describes the logical ordering of the fields for the protocol. The actual wire format (and typical in-memory representation) has the fields reordered to reduce Data structure alignment issues. This can be a source of confusion when reading the code generated from the message definitions.

MAVLink Ecosystem MAVLink is used as the communication protocol in many projects, which may mean there is some compatibility between them. A tutorial explaining basics of MAVLink has been written.

Worked examples

Example 1 — a first encounter with MAVLink

Start with the simplest possible case. Write down what MAVLink claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MAVLink before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MAVLink ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MAVLink

In research: MAVLink appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MAVLink in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MAVLink is common in secondary-school and first-year university syllabi. It links to neighbouring topics Application layer protocols, Avionics, Robotics engineering, so understanding it makes those chapters shorter.
In everyday life: Look for MAVLink outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study MAVLink in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MAVLink means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MAVLink out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MAVLink in simple terms?

MAVLink or Micro Air Vehicle Link is a protocol for communicating with small unmanned vehicle. It is designed as a header-only message marshalling library.

Why does MAVLink matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MAVLink?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MAVLink.