04_Handout_1(21).pdf

IT2102 Communications and Protocols Types of Processor Communication Outbound Embedded systems utilize microprocessors as the main control element in various kinds of measurement or control systems. I/O subsystem views the hardware and software within the range of communica...

IT2102 Communications and Protocols Types of Processor Communication Outbound Embedded systems utilize microprocessors as the main control element in various kinds of measurement or control systems. I/O subsystem views the hardware and software within the range of communication: o Local devices – These devices tend to be in closer proximity (1 - 3m less) to the core system and typically have proprietary or specialized interfaces. ▪ Any tasks executing on such devices are usually associated with the function of the specific device and are not considered to be part of the embedded application proper. o Remote devices - These devices tend to be located at a greater physical distance (3 - 5m more). ▪ Interaction with remote external devices begins with the notion of distributed tasks executing on these devices and forms. Inbound Information must be communicated before it can be processed in an embedded system. Information can be communicated through various channels and beyond. o Channels are abstract entities characterized by the essential properties of communication. o The physical entities enabling communication are called communication media: wired or wireless. Communication and Synchronization Model (Peckol, 2019 & Mardewel, 2018) The requirements for synchronization and for exchanging data and information among tasks are to be identified through protocol standards and interfaces. The information is the data or signals being moved that convey the intent or goals. o It will be expressed either directly (voltage, current, or electromagnetic wave) or indirectly (information, data or signals, pressure, strain, sonic, or temperature). ▪ The nature of the information: unidirectional and bidirectional. o Techniques for electrical robustness: ▪ Single-ended signaling - signals are propagated on a single wire. These are represented by voltages with respect to a common ground and are susceptible to external noise. ▪ Differential signaling - each signal needs two wires propagating binary values. Twisted pairing is used to lessen noise. Places refer to the information, such as data signals, moving to or from an existing system. The source and destination for the exchange extend to locations outside of the local address space. o Point-to-point - It is the interaction with a specific component, system, subsystem, or other piece of equipment. ▪ The exchange may command a measurement, alter the configuration of the component, perform a specific operation and return a value, set its output to a designated value, or simply request status information. o Broadcast - The destination may include all of the subsystems comprising the application. It is used to send the same information to all components. ▪ The information may direct all member subsystems to a reset state, to initiate a self-test sequence or signal that the state of some system variable has changed and that an update is necessary. o Multicast - It transfers information only to those for whom it is relevant such as a subsystem. Control and synchronization is a combination of both hardware synchronization and software. It controls and synchronization of actions and the movement of the information. o The hardware portion comprises the overall structure and organization of the transport mechanism, any connected devices, and any necessary control signals. 04 Handout 1 *Property of STI  [email protected] Page 1 of 3  IT2102 o The software portion includes a special collection of routines, which are used to manage communication with individual devices or classes of devices. ▪ Driver (Device driver) is associated with each I/O device and supports interaction: ▪ The source or destination for any exchange. ▪ The location of the I/O driver. ▪ The I/O ports on the microprocessor. ▪ The protocol for the data exchange. ▪ Local and global memory address space. ▪ Timing requirements. ▪ Exchange as an event, a shared variable, or a message. ▪ The physical medium of the exchange. ▪ The aspects are characterized by the flow of information, I/O timing, and software drivers. The transport mechanism implies the implementation of moving the information through a variety of physical mediums and configurations. It can be a piece of wire, a bundle of fiber-optic filaments, or the surrounding air. Communication Protocols Protocol is a set of rules and regulations that is to be followed. One of the functions of these protocols is to exchange messages from one computer system to another. It covers error detection & correction, signaling, and authentication. Communication protocol is a set of rules and regulations that allow two (2) or more electronic devices to exchange data with each other. o The intersystem protocol uses two (2) different devices to communicate such as a computer to a microcontroller kit. The communication is done through an inter bus system. ▪ Universal Asynchronous Receiver and Transmitter (UART) It is a serial communication with two wired protocols in which its data cable signal lines are labeled as Rx and Tx. It transmits and receives the data serially bit by bit without class pulses in a sequential manner via half-duplex protocol. Ex: Emails, SMS, Walkie-talkie. ▪ Universal Synchronous and Asynchronous Receiver and Transmitter (USART) It is a serial communication of a two-wire protocol. The data cable signal lines are the same as UART, which is labeled as Rx and Tx. This protocol is used to transmitting and receiving the data byte by byte along with the clock pulses via full-duplex protocol. Other devices can communicate using a microcontroller with this protocol. Ex: Telecommunications. ▪ Universal Serial Bus (USB). It is a serial communication of two-wire protocol in which the data cable signal lines are labeled D+ and D-. This protocol is used to communicate with the system peripherals. USB protocol is used to send and receive the data serially to the host and peripheral devices. USB communication requires driver software that is based on the functionality of the system. Ex: Mouse, Keyboard, Hubs, switches, pen drive. o The intrasystem protocol is used to communicate the two devices within the circuit board which expands the peripherals of the microcontroller. The circuit complexity and power consumption will be increased by using the intrasystem protocol. ▪ Inter-Integrated Circuit (I2C) It requires only two wires connecting all peripherals to the microcontroller: two bidirectional active wires SDA (serial data line) and SCL (serial clock line) to carry information between devices. It is a master-to-slave communication protocol. ▪ Serial Peripheral Interface (SPI) It is one of the serial communication protocols developed by Motorola. Sometimes SPI protocol is also called a 4-wire protocol consisting of four wires MOSI, MISO, SS, and SCLK. This protocol used to communicate the master and slave devices. The master first configures the clock using a frequency. 04 Handout 1 *Property of STI  [email protected] Page 2 of 3  IT2102 ▪ Controller Area Network (CAN) It is a serial communication protocol that requires two wires CAN High (H+) and m. It was developed by the Robert bosh company in 1985 for in-vehicle networks. It is based on a message-oriented transmission protocol. o IoT Protocols are types of communication that ensure the finest security toward the data being exchanged among the IoT-connected devices. Its main benefits are high quality, credibility, interoperability, innovation flexibility & global scalability. ▪ IoT protocols are available in two types: IoT network protocols and IoT data protocols. WiFi, SigFox, Bluetooth, LoRaWAN, NFC, Z wave, Zigbee, OPC- UA, Cellular, & MQTT. o PLC Protocol (Programming Logic Circuit) depends on the three basic parts: baud rate, length of network, and the number of nodes. Profibus Optomux Ethernet Global Data (EGD) Interbus Host Link Protocol Factory Interface Network Service Protocol (FINS) ControlNet therNet/IP Open Smart Grid Protocol (OSGP) ProfiNet PPI- Point to Point Distributed Network Protocol (DNP3) DF-1 Protocol Ethernet Powerlink Service Request Transport Protocol (SRTP) RAPIENet Multi-Point Interface (MPI) Smart Distributed System Protocol (SDS) o Cloud Computing Communication Protocol supports two (2) protocols through Cloud IoT Core. ▪ Message Queuing Telemetry Transport (MQTT) is used frequently and it is supported through embedded devices which has common interactions from a machine to another. ▪ Hypertext Transfer Protocol (HTTP) is a connectionless protocol, so devices do not maintain a connection to the cloud IoT core. It is an alternative, they send requests as well as get responses. References: Barkalov, A., Titarenko L., & Mazurkiewicz, M. (2019). Foundations of embedded systems. Springer International. Lee, E. & Seshia, S. (2017). Introduction to embedded systems: a cyber-physical systems approach (2nd ed.). MIT Press. Marwedel, P. (2018). Embedded system design: Embedded systems, foundations of cyber-physical systems, and the Internet of Things (3rd ed.). Springer International. Pan, T., Zhu, Y. (2018). Designing embedded systems with Arduino: A fundamental technology for makers. Springer. Peckol, J. (2019). Embedded systems – A contemporary design tool [2nd ed.]. Wiley. Popular communication protocols in Embedded systems – Part I. (2020, July 29). In Gadgetronicx.com. Retrieved on July 7, 2021, from https://www.gadgetronicx.com/popular-communication-protocols-embedded-systems/ What are Communication Protocols & Their Working. (n.d.). In Elprocus.com. Retrieved on July 7, 2021, from https://www.elprocus.com/communication-protocols/ 04 Handout 1 *Property of STI  [email protected] Page 3 of 3