Tagged Questions

GPIO is an acronym for general purpose input/output. The term is typically applied to a pin on a microcontroller (or other device) that may be changed between an input and output under software control. It can be used for an application defined purpose, as opposed to being constrained to a single ...

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28 views

MCP2200 - which GPIOs for DTR, DCD, DSR and RI?

Due to the recent controversy surrounding FTDI, I'm looking for a replacement for future designs. I'm looking very hard at the MCP2200. The only thing I can't figure out is that they have several GPIO ...
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1answer
57 views

How could this GPIO-controlled LED status blinker be improved?

I'm building a simple circuit to drive an LED status indicator in a project built around a RPi. The circuit takes its power from the same source as the RPi and is connected to one of the RPi GPIO ...
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1answer
51 views

Using GPIO mode in SIM908

I'm working on a SIM908 module using GPIO mode (my rx pin contact is lost when soldering). I have interfaced it with a PIC16F73 and while using GPIO mode I'm not getting any response. I have included ...
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49 views

How can I use the OSC2 pin as normal IO on a pic32mx150f128b?

Everything else works well, the CPU runs at 40 MHz, UART works, GPIO works; the OSC1 pin works as GPIO as well. But I cannot use OSC2 as GPIO. I am using the Fast RC oscillator with divide-by-N and ...
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0answers
38 views

Remotely Toggle Relay

A while back I decided I wanted to get into electronics, after which I bought a number of components to get me started, along with the Raspberry Pi and breadboard I already had. I am now wanting to do ...
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1answer
29 views

Connecting GPIO and SPI signals via cable

There is a requirement in one of our systems to transfer signals from one board to another board in the same system. The signals are GPIOs and SPI lines from I.MX6 processor and it is in 3.3V ...
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2answers
66 views

Connect an ATmega328 to a Raspberry Pi

I've been stuck on this problem for a couple of months now and haven't had much luck finding the exact information that I need. So, I'm currently working on a project to make a handheld raspberry pi, ...
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1answer
39 views

Can features like ADC and PWM on a pin be considered as functions/configurations of a GPIO?

this is more or less a question about wording. I am designing an API and need to figure out whether or not the namespace name used is correct or needs to be refactored. The namespace is called GPIO ...
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3answers
185 views

Is there a GPIO IC that has a parallel interface?

Sorry if this is an obvious question, I come from a software background and don't know the names for a lot of components. I am designing some custom hardware based around a W65C02S processor (a modern ...
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2answers
98 views

Can a digital input having internal pull up resistor drive a load?

simulate this circuit – Schematic created using CircuitLab I am working on MC56F8006 DSC . On power up or reset the default state of all GPIOs is inputs with internal pullups enabled. I ...
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1answer
89 views

GPIO interrupts in alternate mode

Are the interrupts in GPIO module triggered (high to low edge, low to high edge, low level or high level) when GPIO is operating in alternate mode functionality?
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1answer
173 views

Can I loop two GPIO pins on an Arduino/ATmega328?

I'm playing around with some wheel encoder sensors and an Arduino. The sensor needs a bit of debouncing, so that got me wondering how the microcontroller core is seeing the input. That is, what does ...
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1answer
78 views

GPIO Pin configurations [duplicate]

I went through the data sheet of STM32F4 and found the pin configuration of GPIOs. I dont understand the difference between these configurations. • Input floating • Input pull-up • Input-pull-down • ...
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0answers
59 views

Spurious interrupts using switches on a Raspberry Pi

I have two switches connected to GPIO pins on a raspberry pi. One side of each switch is wired to +3.3v. The other side is connected to an input pin via a 330 Ohm resistor, and each input pin has a ...
1
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1answer
145 views

Two or more different regulators connected to one battery

I want to make batteries provide power to both a micro controller (Raspberry Pi) and a 4x4 LED matrix. A simple circuit diagram is shown below. (only one LED is drawn in the fig. But regard it as LEDs ...
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0answers
50 views

Parallel Write On External Clock on STM32

I am using 8 GPIO pins on an STM32F407 for a parallel write to an external device (FT232H). The parallel write is synchronous, ie. I have to synchronize my data to a clock provided. According to the ...
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3answers
137 views

How to wire 12 cameras to trigger simultaneously

In the documentation of a camera it says: "To activate a GPI trigger, momentarily short pin 2 to 1." But I have 12 cameras and I want to trigger 12 cameras at the same time, how should the ...
0
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1answer
37 views

Configure GPIO pin for infrared interface (IRTIM) of STM32F030x4/x6/x8

I have a problem for use infrared interface (IRTIM) of my MCU. When I saw in Reference manual I could find this: Now, when I search for find GPIOx_AFRx register, I cannot find this register in ...
0
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1answer
38 views

SX1509 Analog to Digital Converter?

I purchased this product: https://www.sparkfun.com/products/11502 I've wired it up to 5 membrane pressure sensors which provide variable resistance depending on the pressure exerted. However I'm not ...
0
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1answer
58 views

pwm or gpio for pled display on beagle bone? [closed]

Wondering which adafruit bbio library i should use. I know nothing. My sense is that GPIO will be simpler to communicate the display info to the screen. The screen is a 128x32 adafruit pled
5
votes
3answers
125 views

Dump Flash Memory through a single GPIO pin

I'm working with Infineon's XMC4500 Relax Kit and I'm trying to extract the firmware through a single GPIO pin. My very naive idea is to dump one bit at a time through the GPIO pin and somehow ...
0
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1answer
103 views

How does a stm32f chip set its GPIO speed? (hardware, not register setting)

The speed of GPIO of a stm32 chip is set by register of OSPEEDR. It shows: 00: Low speed 01: Medium speed 10: Fast speed (50MHz in library) 11: High speed (100MHz in library) My guess is ...
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0answers
52 views

Communications between ArduPilot Mega and BeagleBoneBlack

I am trying to send complex control commands from BeagleBoneBlack(BBB) to ArduPilot Mega(APM) 2.5, such as loitering and acquire GPS location. The documentation on APM is somewhat dated and vague. I ...
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1answer
243 views

Beaglebone Black GPIO pins not working

I plugged a simple LED circuit that I've tested elsewhere into the Sys_5V (pin p9_7) and GND (pin p9_1). Then I tried p9_23 GPIO and set it to digital high it didn't work either. Why also: Sys_5V ...
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0answers
129 views

GPIO in device tree

My board has 3 GPIOs, namely gpio0, gpio1 and gpio2. Each of them have 32 pins. They were ...
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2answers
93 views

Would driving transformer with MCU's GPIO cause durability issue?

For making isolated power supply, I would like to drive a transformer with two GPIO's of a MCU. The center tab of the primary will be connected to Vcc. And each end of the primary will be toggled ...
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4answers
164 views

How to drive LED when sinking current to MCU?

Hopefully a simple one. Should I always control by writing to the GPIO digital output? Or should I always leave it low and then tri-state the output? LED turns on when MCU pin sinks current: In ...
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2answers
488 views

How to create USB toggle switch controled by GPIO

I have Raspberry Pi setup as NAS. The storage is external HDD powered through USB. I would like to encase this whole thing in some nice box and still be able to easily use the HDD, without ...
0
votes
3answers
372 views

Understanding GPIO analog and digital

I'm trying to understand GPIO, and have read a bunch of different blog posts and I think I'm close to getting it, but still struggling with a few things. I've seen a few reference to GPIO only being ...
1
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3answers
514 views

Proper usage of a MOSFET to control USB

On the RaspberryPi.SE it was suggested that one can use MOSFET BS170 to switch a USB device on and off by a GPIO pin (3.3V). I need to get 500mA to power a GSM dongle; the voltage drop should ...
1
vote
1answer
149 views

Is it possible to get input from a 10x10 grid of switches using an arduino board? (Uno, Mega, etc.)

I'm more of a software guy but I'm working on a prototype of a game that will use a pressure sensitive 10 by 10 grid. This will require 100 switches just for the grid. The closest I've found to off ...
1
vote
3answers
312 views

Drawbacks of using single-ended communication over differential pairs

I recently bought a ZYBO FPGA board only to find out that there are exactly six regular single-ended GPIO lines wired to the FPGA. In contrast to that, 18 differential lines are available. The board's ...
0
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0answers
106 views

Xilinx Spartan3-E FPGA input impedance and input leakage current for the GPIO pins

I am trying to use one of SPARTAN3-E FPGA GPIO pin as an input to ADC. I want to know the input impedance and the leakage current for GPIO? Should I just connect my circuit's Vout to GPIO pin or ...
1
vote
1answer
49 views

Interfacing GPIO pins between a uC and RS-485 tranceiver

uC: EM357 datasheet RS-485 IC: sp3078e datasheet Two input pins on the sp3078e need to go high at the same time when I'm sending bytes. I'm using a single output pin on the EM357 to drive both of ...
3
votes
2answers
388 views

Cannot get a digital square wave on oscilloscope from the GPIO of the Raspberry Pi?

ENVIRONMENT: Running "Raspbian" on Model_B Raspberry Pi (Revision 2) w/ ribbon expanding the GPIO out onto a Breadboard as shown in the following image. SETUP Here is a close up of the GPIO ...
4
votes
2answers
963 views

Does driving an microcontroller's GPIO when it is powered off weaken the chip?

We are using the LTC5800-IPM microcontroller in a project. The way our design is now, the IC's GPIO pins will sometimes be driven high (to 3.3V) or low when it is powered-off. Will this weaken the ...
2
votes
3answers
174 views

Does a clamping current specification under Absolute Maximum Ratings imply that less current is OK?

I have an application where I want many small signal relays driven by an I/O expander chip. In this case, I have selected the Microchip MCP23017 (Datasheet) as an I2C to GPIO expander. I have also ...
1
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0answers
136 views

MSP430 GPIO behaviour on power off

I have a simple circuit which contains an MSP430 connected to a DAC8551. I'm using PORT1 so have implemented a bit-banging approach instead of using the USCI module (bad, I know). I've noticed a ...
3
votes
1answer
347 views

GPIO on PIC16F887 not working

I've set the PIC16f887 on both external crystal 20MHZ and internal oscillator 4MHZ, neither of them ever worked with the following code: ...
1
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1answer
113 views

Use voltage regulator instead of zener to protect GPIO

I've read several articles about protecting 3.3v GPIOs from unregulated over voltage, all of which involve using a zener diode, a diode for reverse protection and resistors in some fashion. example 1 ...
2
votes
1answer
90 views

Frequency Sensitivity of GPIO Pins

When reading from a GPIO pin, at what frequency do the crests and troughs of a wave begin to blend together to the point that the CPU can no longer distinguish between them? I assume the answer ...
0
votes
1answer
68 views

Reduce voltage to read buzzer with GPIO

Using the GPIO on a BBB I'm attempting to detect a change in voltage coming from a DC source that drives a buzzer when the machines cycle is complete. I've located the DC connections from the machines ...
0
votes
1answer
145 views

problems using atmega644pv jtag pins as gpio [closed]

I've been trying to use port C pins on an atmega644pv as gpio, and have been running into some trouble. as far as i can discern, it seems like the middle four pins (PORTC 2,3,4,5) are stuck in a high ...
0
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4answers
256 views

GPIO/PCIe programing

I want to connect a PCIe 16x 3.0 GPU card to a Raspberry pi. I don't mind lo loose bandwidth, i just want to use the core GPU capabilities. So, the only idea that came out to my mind is to use the 26 ...
-1
votes
1answer
455 views

How to wire/interface a 4x3 membrane keypad

I followed this example to wire my keypad to my STM32F4 Discovery board. However any way I read data on the pins I keep getting same data which leads me to believe I wired something wrong. Here is ...
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votes
2answers
324 views

internal circuitry of IO ports in MCU [closed]

Could anyone share the internal circuit(transistor level circuit) of GPIO section in a microcontroller? I am curious to see how a pin can serve as both input or output(of course only one at a time). ...
0
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1answer
103 views

Raspberry pi with direct relay

I have a very back to basics question. I've been using a 5v relay with the raspberry pi. The relay trigger is connected directly to an output pin and the other side is connected to the ground of the ...
0
votes
1answer
96 views

Is this circuit a viable implementation? [duplicate]

Following on from an earlier question where the implementation was flawed, can anyone advise if the below is a viable implementation of a circuit to handle a matrix keypad? The idea is that one ...
1
vote
1answer
97 views

2 logical inputs on the same circuit

Is the below a valid circuit implementation and are there any things to watch out for? It's a simplification of the larger circuit but the crux of it is that I need to sink current into two GPIO input ...
2
votes
3answers
1k views

Max switching frequency of GPIO pins of modern cheap FPGA

How can we estimate maximum switching frequency of GPIO FPGA pins? What is maximum data rate achievable when connecting two FPGAs together without using of integrated high-speed transceivers? Or when ...