Introduction to MOST Protocol: The Backbone of In-Vehicle Infotainment
Published: 2023-12-21 05:03:23

Hello Readers, 👋😍 My name is Nagaraj B H and I am a Junior Software Engineer at Luxoft India. Luxoft gave me several opportunities to work on many projects that made me discuss important strategies for MOST communication protocol. Here we talk about MOST communication protocol in detail.

**Introduction:** In the continuously evolving automobile technology surroundings, efforts were made to enhance the user experience in the vehicle. One of the crucial additives permitting this change is the **Media Oriented Systems Transport (MOST) protocol**, regularly called the backbone of in-car infotainment structures. Basically, the MOST protocol is a high-pace multimedia community technology designed specifically to switch data among unique components of a automobile. The motive for its introduction changed into the want to facilitate the smooth go with the flow of facts to fulfill the more and more complicated necessities of present day vehicles. The motives behind the improvement of MOST are electromagnetic compatibility (EMC) and the weight and size of connectivity structures for multimedia system in motors. For instance, don't forget a basic gadget with a multimedia participant, a cell phone interface, and a radio with a user interface (4 additives).
![Image description](https://dev-to-uploads.S3.Amazonaws.Com/uploads/articles/axlhnbxb0zyctkcrr2oe.Png)

**The benefits of the usage of MOST for multimedia data transmission are as follows.** 
1. More controllable EMC troubles 
2. Fewer cables and plugs 
3. Shorter cable duration. 
Four. Less weight and smaller quantity 
5. Better reliability and lower expenses 

**Media Oriented Systems Transport Frame Format:** MOST protocol uses a specific body format to transmit statistics and control signals among community nodes. Understanding this body layout requires reading and decoding the statistics exchanged right here. The MOST25 protocol body layout consists of a 1-byte header, wherein bits are used for synchronization. The last bits inside the header suggest the wide variety of quads to be had for streaming data in the packet. Control data and body manipulate information follow the header, with every control message being 32 bytes in length.  The header in MOST50 format incorporates eleven bytes, including subfields including driver, key flag and control data. The MOST150 header is just like the MOST50 header, but includes an additional byte for introductory statistics.

**Architecture of a MOST Network:**
The MOST series bus supports the fast growth of multimedia devices in current vehicles. The MOST specification defines the bodily and verbal exchange layers and seven layers of the ISO/OSI version. The integration of the MOST protocol into multimedia gadgets is simplified thru standardized interfaces. For multimedia tool designers, MOST presents a communique protocol and access to tool features via a standard API. MOST web services motive force software helps verbal exchange and consists of middle layer system services (layer 3, , 5) and application shell offerings (layer 6). The BEST web offerings controller elements support the BEST protocol between the Layer 7 API and the physical layer community interface controller.
![Image Description](https://dev-to-uploads.S3.Amazonaws.Com/uploads/articles/s1qrk7sqs9qs9gbjcfl1.Png)

**Automotive MOST Network Services:** Nodes of the MOST community have exceptional functional blocks implemented over the statistics communique layer. One key block is the NetBlock, which is chargeable for popular tool control, inclusive of locations, group/logical addresses, and greater. Each community node is defined based on its area. The Media Oriented Systems Transport specifications define the allowed deal with degrees in 16-bit layout. The node acting as the scheduling host is assigned function 0, and next nodes are assigned innovative positions primarily based on their link order. 
The node address is determined with the aid of adding the value 0x 00 to the location. MOST also permits organization addressing, wherein gadgets of the identical elegance, inclusive of amplifiers or infotainment gadgets, may be assigned the equal institution cope with and controlled in a single body. Specific addresses are defined for blocking off and non-blocking off transmission, which guarantees green communication on the network.

**How the MOST bus works:** To understand how the MOST bus works, imagine a subway network with only one set of tracks. This network is a closed loop and your train can only travel in one direction. And because we want our network to be very fast, we use optical fiber to transmit the signal, and our signal is basically a red light. To generate a sign, we first need to enter the records into our amusement machine. For instance, starting the car or converting the radio station from the faraway manipulate is taken into consideration input. When the host registers an enter, it generates a sign and triggers it at the MOST bus. 
The signal then travels through the community and passes through each device including Bluetooth module or sound amplifier connected to that bus, just as a subway train passes thru each station. The range of stations depends on the wide variety of options or capabilities provided via the infotainment gadget, which range from automobile to vehicle. These stations include a Bluetooth module, AM/FM tuner, audio amplifier, etc. After passing via all the stations, it returns to the main unit, which contains the main computer, therefore forming one complete circuit.
![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/uvd16va1gy2o72ppgg5y.png)


 
**Conclusion:** Basically, the MOST protocol is a leader within the subject of car infotainment structures and helps the seamless integration of numerous multimedia and manipulate systems into cars. Its ability to effectively process excessive-bandwidth information at the same time as making sure reliability and fault tolerance will increase its significance in shaping the modern-day car enjoy. As automobile technology evolves, the development route of the MOST protocol stays vital and promises new improvements and integrations on the way to in the long run redefine the manner we experience in-car entertainment and connectivity.