Questions tagged [gpio]

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 designated function.

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MAX3232: Switch between RS-232 and TTL levels

Sorry in advance, electronics noob here! I need to make a proof of concept to get some data out of third party system which handles both RS232 and TTL levels. The computer/raspberry/arduino shall - I ...
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External Interrupt Peripheral Microcontroller

I'm using this ATSAME53N20A-AU microcontroller - Link I'd like to know what does the EIC and EXTINT peripherals would do? So, I went through the Appnotes - EXTINT and EIC I just want to know whether ...
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LED Current Draw Questions

I need a little help with understanding the current I'm working with. I have these LEDs, and trying to power them with an Arduino type board, a Wemos/Lolin D1 R1, based on an ESP8266. I measured the (...
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How to use a small board computer's gpio to close a switch on an external device

I'm using an Odroid XU4. It outputs 1.8V on the GPIOs. I have a USB2 Hub connected to it which has its own power supply (connected, alongside the Odroid to a pico PSU). Problem is, it has a physical ...
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Circuit to enable/disable ESP32 GPIO pins during bootstrap

I am developing an ESP32 board and I need to use all the GPIO pins of the ESP32. But I have some problems during bootstrap, since: some GPIOs emit a PWM signal which can affect the connected circuits;...
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Running a thermal camera (AMG8833) with an orange/raspberry pi but i2cdetect cannot detect any of the 2 cameras

I have bought 2 AMG8833 thermal cameras from different sellers. I tested both first with an orange pi zero and later with a raspberry pi zero. On the orange pi, I used the following GPIO pins and ...
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Is ESP32's GPIO25 Pin adc1 or adc2?

I am trying to design a PCB with ESP32 and a Lora module I want to use serial1 for Lora RX/TX communications. I saw a board which is using GPI35 to Lora RX and GPIO25 to Lora TX. But in same time ...
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Why is a resistor needed for the transistor base in this circuit?

I want to use a fan for my raspberry pi and want to switch it on and off. I have found a tutorial online which I want to summarize below: Components: the 5V fan (DC motor in the image) 680Ω resistor ...
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Why wouldn't an SPI SCK pin be a GPIO OUT pin too?

I have an ATtiny261 MCU. The pin diagram shows 2 digital out pins, PA1 and PB1. I've found a need for a 3rd output pin. From my (very) basic understanding of SPI, the clock is triggered on a rising or ...
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Can I drive a low-voltage MOSFET gate directly from a microcontroller?

We're working on this project for school where "reducing the number of components is essential". We need to operate a little brushed DC motor so we thought of using a simple low-side drive ...
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Why is my infrared receiver working on my Beaglebone Black but not my Raspberry Pi?

I have a TSOP4438 wired to GPIO pins of a Raspberry Pi Zero W and Beaglebone Black as shown in the diagram: I'm trying to use this to control my Pi with an old Roku remote. I initially tried this ...
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How can I test if a GPIO pin on a microcontroller has been damaged by ESD?

I need to test if a microcontroller's pins are damaged after hitting it with an ESD gun. The microcontroller I'm testing is the STM32H743. The only method I have come up with so far is to just Toggle ...
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Driving GPIO outputs with FPGA: How to guarantee outputs of pins are set at same time

I was recently asked a question by an interview. We were discussing a hypothetical device that needed to drive 8 GPIO outputs of the FPGA. I was asked how to reduce the influence of propagation delay ...
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Controlling flip/vane clock digits

I've obtained a vane/flip clock which has 4 digits, but the controller is long gone. I plan to control the clock using a Raspberry Pi and the usual relay boards you get for them - I've done something ...
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Can I Safely Use Serial1 of ESP32 with GPIOMATRIX?

I am trying to use ESP32 with a Lora module and HMI display in a same project. So I need 2 UARTS. I have connected Lora module (e32 900t20d) to RX2 (GPIO16), TX2 (GPIO17). Also I want to connect my ...
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A few basic questions regarding MCU pins

I'm using a tm4c123g tiva launchpad, but I believe these questions are general. If a pin is set to output, what does it mean to "apply a different voltage on it"? This is followed by ...
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EEPROM with GPIO [closed]

Trying for a while now, but I cannot find an EEPROM memory with some address bit mapped to a GPIO. Or from a different angle, a GPIO expander with an EEPROM memory to save the config. Do such devices ...
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Reducing signal voltage with pull-down resistor

I have a signal that is really high compared to the inputs of a microcontroller and i have to step it down a bit.... Can I use a pull down resistor between the signal and the GND? Will this step down ...
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Using a SP3T switch to connect 2 GPIO and the GND pin of an MCU

I tried looking for an answer for several days, but didn't have any success, so I thought I would ask here. I apologize in advance if this was already answered, and that I was not able to find it in ...
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2 answers
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Protecting MCU digital input with 300m wires

I need to protect the inputs and a 3.3V MCU (ESP32) from damage (eg lightning) and noise with a switch connected at the end of a cable that can be hundreds of meters long. Based on the schematic (Fig ...
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Minimum current required to toggle GPIOs on STM32 microcontrollers

While GPIOs on controllers (STM32F and L series with respect to this question) are voltage driven, do they require a small amount of current? If so, what is the minimum amount of current that is ...
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MCU GPIOs internal pull-ups with external voltage divider

I am designing a board based on STM32F7 with a dozen of Digital inputs that need to be 12V tolerant. On the first design, I was using a voltage divider to have the right logical high detection when ...
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First attempt at a circuit design for Raspberry Pi

The last time I did any electronic design myself was about 12 years ago, I'm hoping to turn this schematic into a PCB and solder it all up eventually but I am so out of my depth trying to relearn this ...
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Can high GPIOs sink current?

The DRV103 has an input, which sources a constant current. A Resistor is used to configure the parameter associated but it is also possible to apply a voltage, if it can sink that current (A few µA). ...
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STM32 - two-way bus gpio configuring

I need to connect stm32 to a two-way bus. Then I have to read/set bus state (it doesn't matter - using interrupts or not) to get/transmit some pieces of data from the bus. This is a custom bus (8-12 ...
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LED wired to GPIO in an unconventional way

I was looking at a schematic for an existing board, and I was surprised to see that this LED was wired up to a GPIO pin (LED1 label), but as if the current was gonna go to ground "inside" ...
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3 answers
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How to trigger a physical button on an external device with a Raspberry Pi's GPIO by shorting the circuit

I'm very new to electronics so this is probably a very simple question. I have a TV decoder that I want to control the "UP" button with via a Raspberry Pi I have on hand. The "UP" ...
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Why would a digital input require a pulldown instead of a direct connection to the input voltage?

I've seen datasheets for certain ICs recommend using a 100 kOhm (or so) pulldowns or pullups for setting configuration inputs. What could be a typical reason for this? Normally I would just tie the ...
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Connecting Nexys to breadboard

I want to connect Nexys 4 DDR FPGA board to a circuit on a breadboard (using pins on the "PMOD header"), but I am a bit worried about accidentally damaging the FPGA: like, for example, by ...
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ULN2003 Relay Driver (recurring problem)

There are 7 relays on the board and a ULN2003 relay driver to control these relays. The BCM pins to the relay driver are marked in yellow below. BCM pins are IO pins from Jetson Nano Development Kit. ...
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Grounding GPIO with separate PS to relay (not relay board)?

I am trying to control a 12 VDC Bosch Automotive relay with an RPi. I am using a separate 12 VDC power supply to trigger the relay. The RPi is using GPIO18 which is connected to a 1k resistor, which ...
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How to receive input signal on Raspberry pi GPIO from transistor emitter

I'm trying to build a simple circuit that allows a Raspberry Pi to detect AC voltage in piece of wire inductively. I have the following circuit which basically uses an antenna wrapped around the wire ...
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Where are the GPIO pins on Digilent Basys 3 FPGA Board?

I do not have a great understanding of electronics circuits and their fabrication. So please pardon me for the noob-ness of this post. In one article that I am reading now, they have attached wires to ...
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How to add LEDs to a microcontroller's GPIO pins, without affecting the normal pin behaviour?

For educational purposes, I have to design a simple ATtiny24 based development board and add some LEDs to its IO ports for better demonstration of digital inputs or outputs. Despite being educational, ...
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3 answers
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What is gpio bank?

embedded and BSP newbie here. Recently I found a term named "gpio bank", but I cannot find good resources from google. What's it? difference of gpio bank and gpio controller? difference of ...
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What is the input and output current of the GPIO pins of a microcontroller?

I am trying to find the current sunk and sourced by the GPIO pins of the STM32G030 (STM32G030x6/x8). It says on page 40 of the datasheet: The output current sunk by any I/O and control pin When it ...
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Decoupling Capacitor on GPIO instead of connected directly to battery

I am building a device that is for most of the time in sleep mode. When woken up, I am sending some BLE signals and use a LED. To support the battery I have a 2u2F capacitor. But because my battery is ...
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GPIO is too senstivie

I've encountered a weird problem and I'm not sure whether it's actually a problem or everything's ok. But going straight to the point. I've got Raspberry Pi Zero W, one of its pins is configured as ...
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How to use GPIO on STM32 (F103VET6) as a kind of of output battery?

After I learnt how to blink LEDs on the board, I came up with the idea of making a LED matrix. The schematic is like this: But I could not figure out how to light it! Every LED can be lighted under 2....
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Does XC8 have a particular way to set or clear GPIO pins?

I'm using MPLAB X and XC8 to compile a simple project for the PIC16F886. To manipulate the GPIOs, what I'm doing is ...
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What GPIOs in NodeMCU are usable

I am running out of usable GPIOs in my NodeMCU esp8266 board. I'm making a car. For the car I use L298N motor driver with 4 gear motors. The pins of L298N motor driver is connected as like this, 1.ENA ...
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Why does Raspberry PI reduce input voltage on GPIO Pin?

We have a cadence/pace sensor for a bike, and we want to retrieve the "sin" by plugging it to a GPIO Pin of a Raspberry PI. The signal "sin" has a voltage that varies between 0 and ...
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3 votes
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PWM use in dsPIC3EV - XC16

I'm learning to use dsPIC33EV and XC16 for a project where I need 4 PWM outputs, but I'm not sure if the PWM outputs of this uC are independent because they are named like PWM1H and PWM1L. Can I use ...
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Reading wrong values from GPIO when connected with a 1 MΩ resistor

I'm trying to re-implement the Arduino Capacitive Sensing Library. In the process, I need to read one GPIO's state with another GPIO. The board I'm using is a ESP-01S with the ESP8266 microcontroller. ...
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Wiring to control 12V relay (SRD-12VDC-SL-C) manually

I am trying to use Raspberry pi to control a 12V relay. Before doing that, I try to do it manually. Below is my wiring based on reference 1 and reference 2. In this wiring, the PWR light is on. ...
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Understanding peripheral multiplexing on MCU pin

I'm creating a board using an ATSAMS70 microcontroller, and found out in the datasheet that the I2S data out pin (which I'll be using) was multiplexed with another pin I wanna use, which is the SD ...
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Calculate resistor value for GPIO pin on Raspberry Pi for input mode

I want to place a 4-way DIP switch to enable setting the "operation mode" for my Pi project. The GPIO pins will be in "IN" mode with "PullDown" flag enabled. How do I ...
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Trying to control 20 loads using MOSFETs and Raspberry Pi GPIOs (NOT WORKING)

I have twenty 12V/450mA Solenoid Valves that I am trying to control using RFP30N06LE MOSFETs (n-type) as switches controlled by a Raspberry Pi 4B+. The gate threshold voltage of the MOSFETs are ...
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Best way to provide clean 5 V to multiple Raspberry Pis

I am trying to power about 20 Raspberry Pis at once using the GPIO pins. Each Pi has about 15W power requirement (3A @ 5V). So 20 Pis would have about a 300W power requirement. There are a few ways to ...
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ULN2003 relay driver

I designed a Raspberry Pi shield PCB. There are 6 relays on the board and a ULN2003 relay driver to control these relays. The BCM pins to the relay driver are marked in yellow below. When two relays ...
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