143:
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127:
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magnitude of the process control signal. For example, when controlling light intensity, the light may be dimmed by reducing the GPIO duty cycle. Some analog processes require an analog control voltage. In such cases, it may be feasible to connect a GPIO, which is operated as a PWM output, to an RC filter to create a simple, low cost
294:(or mechanical or solid-state relay), a GPIO may be used to control high-power devices such as lights, solenoids, heaters, and motors (e.g., fans and blowers). Similarly, an input buffer, relay or opto-isolator is often used to translate an otherwise incompatible signal (e.g., high voltage) to the logic levels required by a GPIO.
59:
GPIOs have no predefined purpose and are unused by default. If used, the purpose and behavior of a GPIO is defined and implemented by the designer of higher assembly-level circuitry: the circuit board designer in the case of integrated circuit GPIOs, or system integrator in the case of board-level
328:
Although GPIOs are fundamentally digital in nature, they are often used to control analog processes. For example, a GPIO may be used to control motor speed, light intensity, or temperature. Usually, this is done via PWM, in which the duty cycle of the GPIO output signal determines the effective
185:
Like IC-based GPIOs, some boards merely include GPIOs as a convenient, auxiliary resource that augments the board's primary function, whereas in other boards the GPIOs are the central, primary function of the board. Some boards, which are classified usually as multi-function I/O boards, are a
115:
In some ICs, particularly microcontrollers, a GPIO pin may be capable of other functions than GPIO. Often in such cases it is necessary to configure the pin to operate as a GPIO (vis-à-vis its other functions) in addition to configuring the GPIO's behavior. Some microcontroller devices (e.g.,
297:
Integrated circuit GPIOs are commonly used to control or monitor other circuitry (including other ICs) on a board. Examples of this include enabling and disabling the operation of (or power to) other circuitry, reading the states of on-board switches and configuration shunts, and driving
142:
341:
GPIO interfaces vary widely. In some cases, they are simple—a group of pins that can switch as a group to either input or output. In others, each pin can be set up to accept or source different logic voltages, with configurable drive strengths and
68:
Integrated circuit (IC) GPIOs are implemented in a variety of ways. Some ICs provide GPIOs as a primary function whereas others include GPIOs as a convenient "accessory" to some other primary function. Examples of the former include the
286:
GPIOs are used in a diverse variety of applications, limited only by the electrical and timing specifications of the GPIO interface and the ability of software to interact with GPIOs in a sufficiently timely manner.
353:
peripheral, or through dedicated IO port instructions. Some GPIOs have 5 V tolerant inputs: even when the device has a low supply voltage (such as 2 V), the device can accept 5 V without damage.
107:
ICs usually include GPIOs. Depending on the application, a microcontroller's GPIOs may comprise its primary interface to external circuitry or they may be just one type of I/O used among several, such as
317:(SPI) bus; these are usually used to facilitate serial communication with ICs and other devices which have compatible serial interfaces, such as sensors (e.g., temperature sensors, pressure sensors,
213:, or combinations of these, may be used to buffer and condition the GPIO signals and to protect board circuitry. Also, higher-level functions are sometimes implemented, such as input
182:
Many circuit boards expose board-level GPIOs to external circuitry through integrated electrical connectors. Usually, each such GPIO is accessible via a dedicated connector pin.
243:
302:(LED) status indicators. In the latter case, a GPIO can, in many cases, supply enough output current to directly power an LED without using an intermediate buffer.
158:
346:. Input and output voltages are usually, but not always, limited to the supply voltage of the device with the GPIOs, and may be damaged by greater voltages.
325:. Taken to the extreme, this method may be used to implement an entire parallel bus, thus allowing communication with bus-oriented ICs or circuit boards.
290:
GPIOs usually employ standard logic levels and cannot supply significant current to output loads. When followed by an appropriate high-current output
186:
combination of both; such boards provide GPIOs along with other types of general-purpose I/O. GPIOs are also found on embedded controller boards and
255:
126:
267:
116:
Microchip dsPIC33 family) incorporate internal signal routing circuitry that allows GPIOs to be programmatically mapped to device pins.
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309:
communication interface. For example, two GPIOs may be used to implement a serial communication bus such as Inter-Integrated
Circuit (
231:
120:(FPGA) extend this ability by allowing GPIO pin mapping, instantiation and architecture to be programmatically controlled.
117:
577:
349:
A GPIO pin's state may be exposed to the software developer through one of a number of different interfaces, such as a
357:
A GPIO port is a group of GPIO pins (often 8 pins, but it may be less) arranged in a group and controlled as a group.
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A "versatile interface adapter", which combines 20 GPIOs with other general-purpose interfaces (
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41:
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210:
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Board-level GPIOs are often given abilities which IC-based GPIOs usually lack. For example,
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56:) board which may be used as an input or output, or both, and is controllable by software.
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ALC260 IC, which provides eight GPIOs along with its main function of
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86:
17:
399:
249:
GPIO interface for
Hewlett-Packard Series 80 computers (HP 82940A)
90:
27:
User-controllable digital signal pin on an integrated circuit
364:GPIO pins can be configured to be input or output
305:Multiple GPIOs are sometimes used together as a
261:Ethernet interface to 48 GPIOs (Sensoray 2410)
237:Network router with three GPIOs (Banana Pi R1)
112:I/O, counter/timer, and serial communication.
313:), and four GPIOs can be used to implement a
8:
474:Oracle Java ME Embedded Developer's Guide
416:
227:
122:
209:inputs, high-current output drivers,
7:
463:
461:
132:Parallel bus interface to 24 GPIOs (
493:"GPIO – Raspberry Pi Documentation"
377:Output values are writable/readable
370:Input values are readable (usually
40:) is an uncommitted digital signal
426:Raspberry Pi – The Complete Manual
380:Input values can often be used as
93:. An example of the latter is the
25:
367:GPIO pins can be enabled/disabled
73:, which interfaces 24 GPIOs to a
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157:
141:
125:
469:"General Purpose Input/Output"
273:Color coded GPIOs (top) on an
118:Field-programmable gate arrays
81:ICs, which interface GPIOs to
1:
360:GPIO abilities may include:
48:or electronic circuit (e.g.
34:general-purpose input/output
384:(usually for wakeup events)
331:digital-to-analog converter
315:Serial Peripheral Interface
594:
533:FreeBSD gpio(3) API manual
521:GPIO framework for FreeBSD
168:with 29 remappable GPIOs (
538:FreeBSD gpioctl(8) manual
553:Linux Kernel Doc on GPIO
526:5 September 2017 at the
424:White, Jon, ed. (2016).
64:Integrated circuit GPIOs
497:Raspberry Pi Foundation
395:Programmed input/output
558:LinuxTV GPIO Pins Info
543:FreeBSD gpio(4) manual
223:pulse-width modulation
188:Single board computers
77:bus, and various GPIO
75:parallel communication
548:ALSA Development List
405:Special input/output
300:light-emitting diode
170:Microchip Technology
83:serial communication
578:Integrated circuits
166:PIC microcontroller
150:MOS Technology 6522
479:Oracle Corporation
442:Imagine Publishing
46:integrated circuit
351:memory-mapped I/O
323:motor controllers
275:Asus Tinker Board
211:optical isolators
178:Board-level GPIOs
16:(Redirected from
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428:(7th ed.).
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528:Wayback Machine
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105:Microcontroller
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573:Computer buses
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515:External links
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477:(8 ed.).
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451:978-1785463709
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438:United Kingdom
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337:Implementation
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319:accelerometers
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225:(PWM) output.
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85:buses such as
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110:analog signal
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500:. Retrieved
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200:Raspberry Pi
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33:
31:
29:
430:Bournemouth
372:high or low
307:bit banging
219:signal edge
172:PIC24FJ256)
99:audio codec
567:Categories
502:3 November
411:References
196:BeagleBone
134:Intel 8255
71:Intel 8255
524:Archived
389:See also
217:, input
215:debounce
190:such as
79:expander
481:. 2014.
434:England
192:Arduino
95:Realtek
60:GPIOs.
448:
321:) and
292:buffer
198:, and
44:on an
400:SGPIO
282:Usage
91:SMBus
504:2016
446:ISBN
382:IRQs
89:and
54:MPUs
50:MCUs
38:GPIO
18:GPIO
311:I²C
87:I²C
42:pin
569::
495:.
471:.
460:^
440::
436:,
432:,
333:.
202:.
194:,
164:A
101:.
32:A
506:.
454:.
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152:)
136:)
52:/
36:(
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
