Embedded software

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Embedded software is computer software, written to control machines or devices that are not typically thought of as computers, commonly known as embedded systems. It is typically specialized for the particular hardware that it runs on and has time and memory constraints. [1] This term is sometimes used interchangeably with firmware. [2]

Contents

A close-up of the SMSC LAN91C110 (SMSC 91x) chip, an embedded Ethernet chip SMSC LAN91C110 ethernet chip.jpg
A close-up of the SMSC LAN91C110 (SMSC 91x) chip, an embedded Ethernet chip

A precise and stable characteristic feature is that no or not all functions of embedded software are initiated/controlled via a human interface, but through machine-interfaces instead. [3]

Manufacturers build embedded software into the electronics of cars, telephones, modems, robots, appliances, toys, security systems, pacemakers, televisions and set-top boxes, and digital watches, for example. [4] This software can be very simple, such as lighting controls running on an 8-bit microcontroller with a few kilobytes of memory with the suitable level of processing complexity determined with a Probably Approximately Correct Computation framework [5] (a methodology based on randomized algorithms). However, embedded software can become very sophisticated in applications such as routers, optical network elements, airplanes, missiles, and process control systems. [6]

Operating systems

Unlike standard computers that generally use an operating systems such as macOS, Windows or Linux, embedded software may use no operating system. When they do use one, a wide variety of operating systems can be chosen from, typically a real-time operating system. Code for embedded software is typically written in C or C++, but various high-level programming languages, such as Java, Python and JavaScript, are now also in common use to target microcontrollers and embedded systems. [7] Assembly languages are often used too, especially in booting and interrupt handling. Ada is used in some military and aviation projects.

Differences from application software

Embedded system text user interface using MicroVGA MicroVGA TUI demoapp.jpg
Embedded system text user interface using MicroVGA

Most consumers are familiar with application software that provide functionality on a computer. However embedded software is often less visible, but no less complicated. Unlike application software, embedded software has fixed hardware requirements and capabilities, and addition of third-party hardware or software is strictly controlled.

Embedded software needs to include all needed device drivers at manufacturing time, and the device drivers are written for the various hardware devices. These device drivers, called BSP (Board support package), form the layer of software containing hardware-specific drivers and other routines that allow a particular operating system (traditionally a real-time operating system, or RTOS) to function in a particular hardware environment (a computer or CPU card), integrated with the RTOS itself. The software is highly dependent on the CPU and specific chips chosen. Most embedded software engineers have at least a passing knowledge of reading schematics, and reading data sheets for components to determine usage of registers and communication system. Conversion between decimal, hexadecimal and binary is useful as well as using bit manipulation. [8]

Web applications are often used for managing hardware, although XML files and other output may be passed to a computer for display. File systems with folders are typically used, however SQL databases are often absent.

Software development requires use of a cross compiler, which runs on a computer but produces executable code for the target device. Debugging requires use of an in-circuit emulator, and debugging hardware such as JTAG or SWD debuggers. Software developers often have access to the complete kernel (OS) source code.

Size of the storage memory and RAM can vary significantly. Some systems run in 16 KB of Flash and 4 KB of RAM with a CPU operating at 8 MHz, other systems can rival contemporary computers. [9] These space requirements lead to more work being done in C or embedded C++, instead of C++. Interpreted languages like BASIC (while e.g. Parallax Propeller can use compiled BASIC) and Java (Java ME Embedded 8.3 [10] is available for e.g. ARM Cortex-M4, Cortex-M7 microcontrollers and older ARM11 used in Raspberry Pi and Intel Galileo Gen. 2) are not commonly used; while an implementation of the interpreted Python 3 language – MicroPython  – is however available expressly for microcontroller use, e.g. 32-bit ARM-based (such as BBC micro:bit) and 16-bit PIC microcontrollers.

Communication protocols

Communications between processors and between one processor and other components are essential. Besides direct memory addressing, hardware level common protocols include I²C, SPI, serial ports, 1-Wires, Ethernets, and USB.

Communications protocols designed for use in embedded systems are available as closed source from companies including InterNiche Technologies and CMX Systems. Open-source protocols stem from uIP, lwip, and others.

See also

Notes

  1. ↑ For more details of MicroVGA see this PDF.

Related Research Articles

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<span class="mw-page-title-main">Embedded system</span> Computer system with a dedicated function

An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is embedded as part of a complete device often including electrical or electronic hardware and mechanical parts. Because an embedded system typically controls physical operations of the machine that it is embedded within, it often has real-time computing constraints. Embedded systems control many devices in common use. In 2009, it was estimated that ninety-eight percent of all microprocessors manufactured were used in embedded systems.

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<span class="mw-page-title-main">PIC microcontrollers</span> Line of single-chip microprocessors from Microchip Technology

PIC is a family of microcontrollers made by Microchip Technology, derived from the PIC1650 originally developed by General Instrument's Microelectronics Division. The name PIC initially referred to Peripheral Interface Controller, and is currently expanded as Programmable Intelligent Computer. The first parts of the family were available in 1976; by 2013 the company had shipped more than twelve billion individual parts, used in a wide variety of embedded systems.

In-circuit emulation (ICE) is the use of a hardware device or in-circuit emulator used to debug the software of an embedded system. It operates by using a processor with the additional ability to support debugging operations, as well as to carry out the main function of the system. Particularly for older systems, with limited processors, this usually involved replacing the processor temporarily with a hardware emulator: a more powerful although more expensive version. It was historically in the form of bond-out processor which has many internal signals brought out for the purpose of debugging. These signals provide information about the state of the processor.

JTAG is an industry standard for verifying designs and testing printed circuit boards after manufacture.

Nucleus RTOS is a real-time operating system (RTOS) produced by the Embedded Software Division of Mentor Graphics, a Siemens Business, supporting 32- and 64-bit embedded system platforms. The operating system (OS) is designed for real-time embedded systems for medical, industrial, consumer, aerospace, and Internet of things (IoT) uses. Nucleus was released first in 1993. The latest version is 3.x, and includes features such as power management, process model, 64-bit support, safety certification, and support for heterogeneous computing multi-core system on a chip (SOCs) processors.

Nios II is a 32-bit embedded processor architecture designed specifically for the Altera family of field-programmable gate array (FPGA) integrated circuits. Nios II incorporates many enhancements over the original Nios architecture, making it more suitable for a wider range of embedded computing applications, from digital signal processing (DSP) to system-control.

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V850 is a 32-bit RISC CPU architecture produced by Renesas Electronics for embedded microcontrollers. It was designed by NEC as a replacement for their earlier NEC V60 family, and was introduced shortly before NEC sold their designs to Renesas in the early 1990s. It has continued to be developed by Renesas as of 2018.

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XMC is a family of microcontroller ICs by Infineon. The XMC microcontrollers use the 32-bit RISC ARM processor cores from ARM Holdings, such as Cortex-M4F and Cortex-M0. XMC stands for "cross-market microcontrollers", meaning that this family can cover due to compatibility and configuration options, a wide range in industrial applications. The family supports three essential trends in the industry: It increases the energy efficiency of the systems, supports a variety of communication standards and reduces software complexity in the development of the application's software environment with the parallel released eclipse-based software tool DAVE.

<span class="mw-page-title-main">ESP8266</span> System-on-a-chip microcontroller model with Wi-Fi

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References

  1. ↑ "Stroustrup on C++ for embedded (bottom p.2)" (PDF). Retrieved 9 December 2012.
  2. ↑ Emilio, Maurizio Di Paolo (2014-09-01). Embedded Systems Design for High-Speed Data Acquisition and Control. Springer. ISBN   978-3-319-06865-7.
  3. ↑ "I.C.S. on embedded software". Archived from the original on 22 March 2013. Retrieved 22 July 2013.
  4. ↑ "Embedded Systems Methods and Technologies". Archived from the original on 29 October 2013. Retrieved 9 December 2012.
  5. ↑ Alippi, Cesare (2014), Intelligence for Embedded Systems, Springer, ISBN   978-3-319-05278-6 .
  6. ↑ http://ptolemy.eecs.berkeley.edu/publications/papers/02/embsoft/embsoftwre.pdf [ bare URL PDF ]
  7. ↑ Mazzei, Daniele; Montelisciani, Gabriele; Baldi, Giacomo; Fantoni, Gualtiero (2015). Changing the programming paradigm for the embedded in the IoT domain. Internet of Things (WF-IoT), 2015 IEEE 2nd World Forum on. Milan: IEEE. pp. 239–244. doi:10.1109/WF-IoT.2015.7389059.
  8. ↑ "Stroustrup on embedded software". Archived from the original on 3 February 2013. Retrieved 9 December 2012.
  9. ↑ "Example of embedded CPU" . Retrieved 9 December 2012.
  10. ↑ "Java ME Embedded". Oracle Technology Network.
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