USB associates NRZI (Non Return to Zero Invert) encoding scheme to transmit data with sync field to synchronize the host system and receiver clock signals. Data packets compose of 8 bits (byte) with LSB (Least Significant Bit) transmitted first. The USB pin out is shown in Figure 4 below.ĭata is transmitted in the form of packets where two devices communicate each other. Apart from two data lines, USB has V CC and Ground signals to power up the device. USB protocol sends and receives the data serially between host and external peripheral devices through data signal lines D+ and D. It allows 127 devices to be connected at any given time.
Universal Serial Bus (USB) is a two-wired serial communication protocol.
between PC and microprocessor kit, developmental boards, etc. Inter system protocols establish communication between two communicating devices i.e. Types of Communication Protocols in Embedded SystemsĬommunication protocols are broadly classified into two types:įig 2 – Classification of Communication Protocols Inter System Communication Protocols The processes such as system configuration, selection of baud rate and transmitting & receiving data is associated with application layer. In general, the communication protocols is associated with physical layer describing the signals incorporated, signal strength, hand shaking mechanism, bus arbitration, device addressing, wired or wireless, data lines etc. 1 – Introduction to Communication Protocols
Many different protocols are available for embedded systems and are deployed depending upon the application area.įig. Each communicating entity should agree to some protocol to exchange information. In this case, the components have to communicate with each other to provide the anticipated output.
A processor or controller takes input from the physical world peripherals like sensors, actuators etc., processes the same through appropriate software and provides the desired output. Communication Protocols in Embedded SystemsĮmbedded System is an electronic system or device which employs both hardware and software. In addition, each protocol has its own application area. Analog and digital communication systems use various communication protocols widely. Protocols can be implemented by both hardware and software or combination of both. The rules, regulations, synchronization between communication systems, syntax to be followed and semantics are all defined by the term protocol. Communication Protocols are a set of rules that allow two or more communication systems to communicate data via any physical medium.