Embedded Systems Interfaces

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Questions and Answers

What does Dynamics refer to in the context of embedded systems?

Dynamics refers to the capability to do actions required in a computing system. It supports all interaction with the outside world in which it passes through so called interfaces.

What are the three main functions of interfaces in embedded systems?

Interfaces establish connection between humans, environment, phenomena, and machines, thus providing input, process, or output.

What are the three levels of understanding for I/O operations in embedded systems?

I/O operations imply communicating with the device. Programming the device to initiate an I/O request. Performing actual data transfer between the device and the system.

The ______ signal rapidly switches between high and low at some fixed frequency, varying the amount of time that it holds the signal high.

Pulse Width Modulation Signup and view all the answers

In active-high logic, a voltage near zero represents a logical one.

False (B) Signup and view all the answers

Tristate logic allows the I/O pin to be adjusted into the off state.

True (A) Signup and view all the answers

What is the standard for connecting teletypes to modems?

RS-232 (D) Signup and view all the answers

What are the two main types of interfaces?

Serial and Parallel (B) Signup and view all the answers

Parallel interfaces typically have speeds above 1MBps.

True (A) Signup and view all the answers

What is the common standard for parallel interfaces and what type of interface does it use?

IEEE-1284 printer port defines a parallel printer bus specification with speeds above 1MBps which uses a point-to-point asynchronous bi-directional interface. Signup and view all the answers

What are the two main types of buses in embedded systems?

Buses can be serial interfaces or parallel interfaces. Signup and view all the answers

What is the purpose of a module in embedded systems?

A module comprises a bunch of electrical components compiled together to form a part of a system that caters to a particular function. It varies depending on how it deals with I/O interfaces, how it is used as requirements, and how it responds to certain exceptions. Signup and view all the answers

What are the three main components of an infrared receiver?

An infrared (IR) transmitter consists of an infrared LED array, which functions as a luminophore, and a PN junction made of a special material with high infrared radiation efficiency, which is usually GaAs. The infrared receiver is a semiconductor device used for translating infrared light signals into electrical signals. The core component of it is a PN junction made of a special material. Signup and view all the answers

Bluetooth wireless technology operates in the ISM band from 2.4 to 2.485 GHz.

True (A) Signup and view all the answers

What are the two main purposes of a GSM/GPRS module?

The GSM (Global System for Mobile Communication) is a digital cellular technology used for transmitting mobile voice and data services. It is also sometimes referred to as 2G, as it is a second-generation cellular network. GSM supports outgoing and incoming voice calls, SMS or text messaging, and data communication (via GPRS). The GPRS (General Packet Radio Service) is a wireless packet data service that is an extension of the GSM network. The GPRS radio resources allocator allows the provision of multiple radio channels to a single user in order to ensure a high data user rate. GPRS offers direct Internet Protocol (IP) connectivity in a point-to-point or a point-to-multipoint mode and provides packet radio access to external packet data networks (PDN). Signup and view all the answers

Wi-Fi is an Ethernet replacement.

True (A) Signup and view all the answers

What are the advantages of wireless technology?

Extended Access. The absence of wires and cables extends access to places where wires and cables cannot go or where it is too expensive for them to go. Cost Reduction. The absence of wires and cables brings down cost. Mobility. Wires tie you down to one location. Going wireless means you have the freedom to change your location without losing your connection. Flexibility. Extended access, cost reductions, and mobility create opportunities for new applications as well as the possibility of creating new solutions for legacy applications. Signup and view all the answers

What is the purpose of an interrupt in embedded systems?

An interrupt is a mechanism for pausing execution of whatever a processor is currently doing and executing a pre-defined code sequence such as interrupt service routine (ISR) or interrupt handler. Hardware interrupt - external hardware changes the voltage level on an interrupt request line. Software interrupt - the program that triggers the interrupt by executing a special instruction or by writing to a memory-mapped register. Signup and view all the answers

What is the main difference between an interrupt and an exception?

Exception - where the interrupt is triggered by internal hardware that detects a fault, such as a segmentation fault. Signup and view all the answers

Atomic operations are guaranteed to complete without being interrupted by other events.

True (A) Signup and view all the answers

What is the purpose of an interrupt controller in embedded systems?

It is the logic in the processor that handles interrupts. It supports some interrupts and priority levels. Each interrupt has an interrupt vector, which is the address of an ISR or an index into an array called the interrupt vector table that contains the addresses of all the ISRs. Signup and view all the answers

Study Notes

Interfaces and Mechanisms

Embedded systems integrate computing and physical actions, interacting with the outside world via interfaces.
Interfaces connect humans, the environment, phenomena, and machines, enabling input, processing, and output.
Physical I/O interfaces handle input/output operations, requiring knowledge of hardware details like programming the device and data transfer.
Pulse Width Modulation (PWM) efficiently delivers variable power to devices by rapidly switching between high and low voltage levels at a fixed frequency.
General-Purpose Digital I/O allows software to read or write voltage levels (high or low), representing logical 1 or 0, for outputs or inputs.
Serial interfaces sequentially transmit bits over a single wire, efficiently using pins and wires.
RS-232, a standardized serial interface protocol created by EIA, is used to connect teletypes to modems, with slower transmission rates.

Common I/O Interfaces

Mechanism: The sender and receiver agree on a transmission rate. The sender sends a start bit, followed by data bits, and one or two stop bits. The receiver's clock synchronizes with the sender's to recover the bit sequence.
USB (Universal Serial Bus) enhances plug-and-play functionality for peripheral devices, allowing hot-swapping.
Joint Test Action Group (JTAG) or IEEE 1149.1, a boundary-scan architecture, is a testing interface for circuits.

Parallel Interfaces

Parallel interfaces use multiple lines to transmit bits simultaneously.
IEEE-1284 is a parallel printer interface specification with bi-directional, asynchronous communication at speeds exceeding 1MBps.
Buses enable communication among multiple devices in contrast to point-to-point interconnections.

I/O Modules

I/O modules are collections of electrical components designed for a particular function.
They handle specifics depending on the type of input/output interface and how they are used as requirements.
Modules handle errors and exceptions. They are also flexible with new or old applications based on need.
Examples of wireless I/O modules include Infrared (IR) transmitters/receivers, Bluetooth, Global System for Mobile Communications (GSM) and General Packet Radio Service (GPRS) modules, and Wi-Fi.

Interrupts and Exceptions

Interrupts: A mechanism pausing a processor's current task to execute pre-defined code (Interrupt Service Routine-ISR). This handles incoming hardware or software requests, or exceptions.
Hardware Interrupts: External hardware signals cause a voltage change on an interrupt request line.
Software Interrupts: The program triggers the interrupt by executing specific instructions or writing to memory registers.
Exceptions: Interrupts triggered by internal hardware faults such as segmentation faults.
Programmable Interval Timer (PIT): A PIT is a hardware component that counts down from a set value and generates an interrupt when the value reaches zero.

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Description

Explore the critical interfaces and mechanisms in embedded systems that facilitate interaction between computing and the physical world. This quiz covers topics like PWM, digital I/O, and serial interfaces, focusing on their roles in input and output operations. Test your understanding of how these components communicate and operate within various applications.