A built-in self-test (BIST) or built-in test (BIT) is a mechanism that permits a machine to test itself. Engineers design BISTs to meet requirements such as:
*high
reliability
Reliability, reliable, or unreliable may refer to:
Science, technology, and mathematics Computing
* Data reliability (disambiguation), a property of some disk arrays in computer storage
* High availability
* Reliability (computer networking), a ...
*lower
repair cycle times
or constraints such as:
*limited technician accessibility
*cost of testing during manufacture
The main purpose of BIST is to reduce the complexity, and thereby decrease the cost and reduce reliance upon external (pattern-programmed) test equipment. BIST reduces cost in two ways:
# reduces test-cycle duration
# reduces the complexity of the test/probe setup, by reducing the number of I/O signals that must be driven/examined under tester control.
Both lead to a reduction in hourly charges for automated test equipment (ATE) service.
Applications
BIST is commonly placed in
weapon
A weapon, arm or armament is any implement or device that can be used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime, law enforcement, s ...
s,
avionics
Avionics (a blend word, blend of ''aviation'' and ''electronics'') are the Electronics, electronic systems used on aircraft. Avionic systems include communications, Air navigation, navigation, the display and management of multiple systems, ...
,
medical device
A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...
s,
automotive electronics, complex machinery of all types, unattended machinery of all types, and
integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
s.
Automotive
Automotive tests itself to enhance safety and reliability. For example, most vehicles with antilock brakes test them once per safety interval. If the
antilock brake system has a broken wire or other fault, the brake system reverts to operating as a normal brake system. Most automotive engine controllers incorporate a "limp mode" for each sensor, so that the engine will continue to operate if the sensor or its wiring fails. Another, more trivial example of a limp mode is that some cars test door switches, and automatically turn lights on using seat-belt occupancy sensors if the door switches fail.
Aviation
Almost all avionics now incorporate BIST. In avionics, the purpose is to isolate failing
line-replaceable unit
A line-replaceable unit (LRU), lower line-replaceable unit (LLRU), line-replaceable component (LRC), or line-replaceable item (LRI) is a modular component of an airplane, ship or spacecraft (or any other manufactured device) that is designed to b ...
s, which are then removed and repaired elsewhere, usually in depots or at the
manufacturer
Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a ran ...
. Commercial aircraft only make money when they fly, so they use BIST to minimize the time on the ground needed for repair and to increase the level of safety of the system which contains BIST. Similar arguments apply to military aircraft. When BIST is used in flight, a fault causes the system to switch to an alternative mode or equipment that still operates. Critical flight equipment is normally duplicated, or redundant. Less critical flight equipment, such as entertainment systems, might have a "limp mode" that provides some functions.
Electronics
Integrated circuit manufacturing
Built-In-Self-Test is used to make faster, less-expensive
integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
manufacturing tests. The IC has a function that verifies all or a portion of the internal functionality of the IC. In some cases, this is valuable to customers, as well. For example, a BIST mechanism is provided in advanced
fieldbus
Fieldbus is the name of a family of industrial computer networks used for real-time distributed control. Fieldbus profiles are standardized by the
International Electrotechnical Commission (IEC) as IEC 61784/61158.
A complex automated industrial ...
systems to verify functionality. At a high level this can be viewed similar to the PC
BIOS
In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the ...
's power-on self-test (POST) that performs a self-test of the
RAM
Ram, ram, or RAM may refer to:
Animals
* A male sheep
* Ram cichlid, a freshwater tropical fish
People
* Ram (given name)
* Ram (surname)
* Ram (director) (Ramsubramaniam), an Indian Tamil film director
* RAM (musician) (born 1974), Dutch
* ...
and buses on power-up.
Computers
The typical personal computer tests itself at start-up (called
POST
Post or POST commonly refers to:
*Mail, the postal system, especially in Commonwealth of Nations countries
**An Post, the Irish national postal service
**Canada Post, Canadian postal service
**Deutsche Post, German postal service
**Iraqi Post, Ira ...
) because it's a very complex piece of machinery. Since it includes a computer, a computerized self-test was an obvious, inexpensive feature. Most modern computers, including
embedded system
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 ...
s, have self-tests of their computer, memory and software.
Unattended machinery
Unattended machinery performs self-tests to discover whether it needs maintenance or repair. Typical tests are for temperature, humidity, bad communications, burglars, or a bad
power supply
A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a r ...
. For example, power systems or batteries are often under stress, and can easily overheat or fail. So, they are often tested.
Often the communication test is a critical item in a remote system. One of the most common unattended system is the telephone concentrator box. This contains complex electronics to accumulate telephone lines or data and route it to a central switch. Telephone concentrators test for communications continuously, by verifying the presence of periodic data patterns called frames (See
SONET
Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diode ...
). Frames repeat about 8,000 times per second.
Remote systems often have tests to loop-back the communications locally, to test transmitter and receiver, and remotely, to test the communication link without using the computer or software at the remote unit. Where electronic loop-backs are absent, the software usually provides the facility. For example,
IP defines a local address which is a software loopback (IP-Address 127.0.0.1, usually locally mapped to name "localhost").
Many remote systems have automatic reset features to restart their remote computers. These can be triggered by lack of communications, improper software operation or other critical events. Satellites have automatic reset, and add automatic restart systems for power and
attitude control
Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc.
Controlling vehicle ...
, as well.
Medicine
Medical devices test themselves to assure their continued safety. Normally there are two tests. A
power-on self-test
A power-on self-test (POST) is a process performed by firmware or software routines immediately after a computer or other digital electronic device is powered on.
This article mainly deals with POSTs on personal computers, but many other embed ...
(POST) will perform a comprehensive test. Then, a periodic test will assure that the device has not become unsafe since the power-on self test. Safety-critical devices normally define a "safety interval", a period of time too short for injury to occur. The self test of the most critical functions normally is completed at least once per safety interval. The periodic test is normally a subset of the power-on self test.
Military
One of the first computer-controlled BIST systems was in the U.S.'s
Minuteman Missile
The LGM-30 Minuteman is an American land-based intercontinental ballistic missile (ICBM) in service with the Air Force Global Strike Command. , the LGM-30G Minuteman III version is the only land-based ICBM in service in the United States and r ...
. Using an internal computer to control the testing reduced the weight of cables and connectors for testing. The Minuteman was one of the first major weapons systems to field a permanently installed computer-controlled self-test.
Specializations
There are several specialized versions of BIST which are differentiated according to what they do or how they are implemented:
*
Programmable built-in self-test (pBIST)
* Memory built-in self-test (mBIST) - e.g. with the Marinescu algorithm
[Marinescu, M., 1982. Simple and Efficient Algorithms for Functional RAM Testing. 1982 IEEE Test Conference, Philadelphia, (Nov.). IEEE Computer Society, pp. 236-239.]
*
Logic built-in self-test Logic built-in self-test (or LBIST) is a form of built-in self-test (BIST) in which hardware and/or software is built into integrated circuits allowing them to test their own operation, as opposed to reliance on external automated test equipment.
...
(LBIST)
* Analog and mixed-signal built-in self-test (AMBIST)
* Continuous built-in self-test (CBIST, C-BIT)
* Event-driven built-in self-test, such as the BIST done to an aircraft's systems after the aircraft lands.
* Periodic built-in self-test (C-BIT/P-BIT)
* Interrupt-driven built-in self-test (IBIST) or user/operator-initiated built-in self-test (I-BIT, or O-BIT)
* Power-up built-in self-test (PupBIST, P-BIT)
* Automatic built-in self-test (ABIST)
See also
*
Built-in test equipment
Built-in test equipment (BITE) for avionics primarily refers to passive fault management and diagnosis equipment built into airborne systems to support maintenance processes. Built-in test equipment includes multimeters, oscilloscopes, discharge ...
*
Logic built-in self-test Logic built-in self-test (or LBIST) is a form of built-in self-test (BIST) in which hardware and/or software is built into integrated circuits allowing them to test their own operation, as opposed to reliance on external automated test equipment.
...
*
Embedded system
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 ...
*
System engineering
Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their life cycles. At its core, systems engineering utilizes systems thinking ...
*
Safety engineering
Safety engineering is an engineering discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering/systems engineering, and the subset system safety engineering. Safety en ...
*
Watchdog timer
A watchdog timer (sometimes called a ''computer operating properly'' or ''COP'' timer, or simply a ''watchdog'') is an electronic or software timer that is used to detect and recover from computer malfunctions. Watchdog timers are widely used in ...
References
External links
Hardware Diagnostic Self Tests- A Brief general overview of the capabilities and benefits of BIST by Analog Devices.
{{DEFAULTSORT:Built-In Self-Test
Test equipment
Integrated circuits
Maintenance