Single-board microcontroller: Difference between revisions

Revision as of 10:16, 19 May 2018

Revision as of 14:28, 11 October 2018

Line 1:

{{Refimprove|date=June 2011}}

[[Image:Mck glamor 320.jpg|thumb|right|The [[Make Controller Kit]] with an Atmel AT91SAM7X256 ([[ARM architecture|ARM]]) microcontroller.]]

A '''single-board microcontroller''' is a [[microcontroller]] built onto a single [[printed circuit board]]. This board provides all of the circuitry necessary for a useful control task: a [[microprocessor]], [[input/output|I/O circuits]], a [[clock generator]], [[RAM]], stored program memory and any necessary support [[integrated circuit|IC]]s. As such, they are a kind of [[System on a chip|System on a Chip]] (SoC). The intention is that the board is immediately useful to an application developer, without requiring them to spend time and effort to develop controller hardware.

As they are usually low-cost, and have an especially low capital cost for development, single-board microcontrollers have long been popular in education. They are also a popular means for developers to gain hands-on experience with a new [[processor family]].

Line 14:

}}</ref> made it practical to build an entire controller on a single board, as well as affordable to dedicate a computer to a relatively minor task.

In March 1976, [[Intel]] announced a single-board computer product that integrated all of the support components required for their [[8080]] microprocessor, along with 1 [[kilobyte]] of RAM, 4 kilobytes of user-programmable ROM, and 48 lines of parallel digital I/O with line drivers. The board also offered expansion through a bus connector, but could be used without an expansion card cage when applications did not require additional hardware. Software development for this system was hosted on Intel's [[Intellec MDS]] microcomputer development system; this provided assembler and [[PL/M]] support, and permitted [[in-circuit emulation]] for debugging.<ref>[http://www.dvq.com/docs/brochures/intel_sbc_80_10.pdf Intel SBC 80/10 Single Board Computer brochure], 1976</ref>

Processors of this era required a number of support chips to be included outside of the processor. [[RAM]] and [[EPROM]] were separate, often requiring memory management or refresh circuitry for [[Dynamic random access memory|dynamic memory]]. I/O processing might have been carried out by a single chip such as the [[Intel 8255|8255]], but frequently required several more chips.

A single-board microcontroller differs from a [[single-board computer]] in that it lacks the general-purpose user interface and mass storage interfaces that a more general-purpose computer would have. Compared to a [[microprocessor development board]], a microcontroller board would emphasize digital and analog control interconnections to some controlled system, whereas a development board might by have only a few or no discrete or analog input/output devices. The development board exists to showcase or train on some particular processor family and, therefore, internal implementation is more important than external function.

Line 25:

It was common to offer access to the internal bus through an expansion connector, or at least provide space for a connector to be soldered on. This was a low-cost option and offered the potential for expansion, even if it was rarely used. Typical expansions would be I/O devices or additional memory. It was unusual to add peripheral devices such as tape or disk storage, or a CRT display

Later, when [[#Single-chip microcontrollers|single-chip microcontroller]]s, such as the [[8048]], became available, the bus no longer needed to be exposed outside the package, as all necessary memory could be provided within the chip package. This generation of processors used a [[Harvard architecture]] with separate program and data buses, both internal to the chip. Many of these processors used a [[modified Harvard architecture]], where some write access was possible to the program data space, thus permitting in-circuit programming. None of these processors required, or supported, a Harvard bus across a single-board microcontroller. When they supported a bus for expansion of peripherals, a dedicated I/O bus, such as [[I2C|I²²C]], One-wire or various serial buses, was used.

== External bus expansion ==

Line 147:

== See also ==

{{Portal|Electronics}}

* [[Comparison of Singlesingle-board microcontrollers]]

* [[Single-board computer]] ([[Comparison of single-board computers|Comparison]])

* [[Comparison of single-board computers]]

* [[Microprocessor development board]]

* [[Embedded system]]

* [[Programmable Logiclogic Controller|PLCcontroller]]

* [[Arduino]]

* [[Make Controller Kit#Make Controller Kit|Make Controller Kit]]