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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Signaling using GPIO pulses [closed]

I have a time pulse signal from UBlox ZED F9P. I need to signal multiple devices from this pin. How should this be done without overstressing this pin? Additionally, connect a LED to this pin.
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Simplest method to reliably detect small currents

I am trying to detect when there is a current in a given circuit using only a digital input and basic components (e.g. diodes, resisters, transistors); current is intermittent and power is small, 40-...
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Why does the voltage drop when I connect an 8 ohms 1 watt speaker, specifically the source to the circuit is GPIO pin output voltage?

This circuit I am using to drive a speaker is acting strangely. Case 1: When I connect the 3.3 volts source from the Nucleo board it works fine as expected (in terms of the sound.) When I check the ...
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How to lock the GPIO pin using LCKR register in stm32f10x series?

I am facing the problem of not able to lock the GPIO pins even after using the LCKK bit sequence to initiate the lock but facing some unknown issues. My references are from HERE, page number 174 The ...
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Logic circuit for not accidentally driving a GPIO output

I am developing a system which will have several devices attached to it. I will have a massive software running on it which controls all of the devices and communicates with different units. One of ...
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GPIO Boundary Address confusion

Background I'm currently digging into STM32L0 series and I stumbled something I couldn't answer. According the the datasheet page 58 we can see all the peripherals are clumped into a section of 512 MB,...
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Can an I2S speaker and microphone share the same I2S clock? What about word select?

If one is very tight on GPIOs, could an I2S TX and RX share any pins? Edit: The device I was thinking of was the ESP32, connected to an I2S microphone and speaker, for example SPH0645 and MAX98357A.
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Using a Raspberry Pi Zero W GPIO to unlock an electronic lock

I want to build a safe that can only be opened via an HTTP POST request. In order to do this the safe will contain a Raspberry Pi Zero W hosting a simple ExpressJS server that listens to these ...
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How to protect a GPIO pin with a long input wire from transients?

I am building a custom doorbell system that will support multiple doorbell buttons and annunciators. I am using an Adafruit Feather and a couple of FeatherWings for each unit. The project can be ...
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What components are inside a port expander, how does it work? (Are they tiny MOSFETs?)

Do port expanders use MOSFETS internally to switch the pins high/low? My project is using a Raspberry Pi and a MCP 23017 port expander to sink some current (to GND through the port expander) from a ...
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What can cause this pin to return to 1 V after connecting it to the Jetson Nano?

I am working on a project where I make a HAT for the Jetson Nano dev kit. (essentially a pi4 with GPU) I am powering the JN with my HAT, which provides 5V to pin 2&4 of the JN. I have a few ...
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Will these optocoupler configuration work to tri-state high voltage GPIOS?

I am trying to control an array of LEDs that require a very high voltage due to the high impedance of the connections (there is no option to change that). Since the charlieplex configuration makes use ...
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Difference between low output GPIO and input GPIO

I have been trying to figure out some details of the GPIO handling. I dont really know anything about electro engineering and am pretty much working with common sense all the time. While researching ...
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ESP8266 Relay with 2N2222 transistors

I have a problem using ESP8266-01 with a relay. I would like to control a 110 V light using a 5 V relay. Here is the circuit I made: I am sure that the code is correct, because when the relay's pins ...
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I/O expander alternative

I am designing a PCB that controls 16-relay or more using micro-controller, but micro-controller does not have enough pins.I searched google and find solution of this problem is I/O expander, but that ...
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Switching a PAM8610 sound amplifier board with a Raspberry Pi or Wemos Di mini GPIO

I'm a complete novice. I want to be able to switch a PAM8610 sound amplifier board, which runs on 12VDC, with a GPIO that outputs 3.3VDC. I know I need some sort of relay. The board draws around 2A ...
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Interfacing DS1302 - is the schematic I found correct?

On the following website there is a project of a 7-segment clock, which uses DS1302 as RTC. The DS1302 is connected to the microcontroller in the way that I don't really understand. Can someone please ...
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Is it possible to add GPIO pins to an old desktop/laptop for use as a development board?

There are many projects online that make use of old computers by turning them into servers etc. I wanted to know if it's possible to turn an old pc/laptop into an x86 development board like the Udoo ...
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STM32 HAL_GPIO_WritePin not working

I am using an NUCLEO-F411RE and try to use the GPIO with HAL. Its the first time i am facing this problem. I initialized the GPIO Pins like this: ...
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Gateworks5910 + TI CC1352 Radio reboot SoC

I am a beginner in embedded systems programming, so forgive me if this is the wrong place to ask, but I could really use some direction. I have a Gateworks 5910 running Ubuntu Linux, which has a TI ...
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Maximum current on gpio header pins (not on device) [duplicate]

I have a lot of low current devices in need of 5V or 12V power. So far I have been using cable connectors like this: The problem is that by "a lot" I am talking about 15-20 devices ...
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Is it generally OK to ignore the current in and out of a MCU pin when analyzing circuit external to the MCU?

From here, I see below illustration about the pull-up resistor. And the article says: With a pull-up resistor, the input pin will read a high state when the button is not pressed. In other words, a ...
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How to detect load is connected to a MOSFET?

How can I detect a load is connected to a MOSFET and report that back to the MCU? So the MOSFET can be ON or OFF, but I need to know in both situations if there's something connected or not. NOTE: if ...
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How do I control a 12V relay with a 1.8V microchip?

Background I have a 12V power supply that is connected to a switching regulator to get a 1.8V power signal. I have a microchip running at 1.8V and want to control a 12V relay via GPIO. The relay is ...
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85 views

GPIO output with pull down resistor

I am using an STM32 microcontroller. I need to have a GPIO output which needs an external pulldown so some relays stay in the right state when the MCU is not running yet. It seems the open drain mode ...
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Transistor circuit design review

I have a customer requirement where we have to design a GPIO controlled switch. We are using NPN transistor, where when the GPIO is high(3.3V) transistor is enabled and it acts as closed switch, when ...
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1answer
122 views

How to add hundreds or thousand I/O pins to a microcontroller?

Suppose that there is a normal microcontroller with i2c port (for example Arduino or Raspberry pi) that we want to extend its i/o ports to hundreds or even thousands. What ways are there to extend ...
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Will this circuit damage my Raspberry Pi GPIO?

I'm making a circuit te be able to shutdown my Raspberry Pi after the shutdown sequence is complete to avoid sd card corruption. The circuit looks like this: A little explanation: The battery input ...
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1answer
50 views

Ideal circuit for opto-isolated push button input

I'm trying de design isolated and robust push button circuit. I have to take precautions for glitching, debouncing and etc. I want to use opto isolator. I draw a simple schematic but I'm not sure if ...
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66 views

Dual control of relay

My current problem, as a noob, is kind of an OR problem. If you feel the urge to call me an idiot or any other choice name. Pleace feel free but I would appriciate if you can explain why. Still trying ...
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ESP32 using Arduino: Internal Pull-ups don't work on GPIO25 or GPIO32

I'm programming a custom ESP32 board using Arduino where GPIO25 and GPIO32 are connected to pogo pins via short 5mm traces and to nothing else. The goal is to poll for a short between them as part of ...
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How many analog inputs can be read and how many digital inputs can be read from STM32F4 discovery board?

I am using STM32F4 discovery board,exact part no. of controller is STM32F407VGT6. The kit has 3 ADCs each of 12 bit and each ADC has 16 channels.I want to read 40-50 analog inputs.Is there some way to ...
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Powering 5V Laser with Raspberry Pi 4 GPIO Pins

I am powering a 5V, 5mW laser that draws ~30mA (KY-008) with a GPIO on my Raspberry Pi 4. From my research, GPIO pins have a voltage output of 3.3V, so I'm not supposed to be doing this. Unfortunately,...
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Can I operate TLC5947 24-Channel, 12-Bit PWM LED Driver by just manipulating GPIO pins on Jetson Nano?

It is often written that Neopixels are not directly controllable by manipulating GPIO pins on SBCs because the precise timings cannot be met, especially when from user space. I need somehow to drive ...
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Why does Basler GPIO need to have an external powersource + resistor to its GPIO output

Background We are usingzBasler camera with an output trigger. The camera output gpio is 3....
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1answer
48 views

Closing a circuit when a GPIO pin is low

I have a GPIO pin that reports when an accessory is connected to the device: the pin is high when there is no accessory and low when an accessory is connected. When an accessory is connected, I would ...
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2answers
315 views

How to interface UART servo? (LX-224HV)

I am trying to interface a RaspberryPi (2B) GPIO-UART to the this serial servo (Hiwonder LX-224HV), as a first step before to switch the Raspberry by an ARM MCU (STM32F407ZE on custom circuit). The ...
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73 views

Floating input pin with external pull-up

I would like to improve the performance of my push buttons, which sometimes don't respond when pressed. They have external pull-up resistors and have been initialised as floating input pins. Does not ...
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3answers
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Connection of two open drain outputs to control common LEDs by PIC32MZ

I want to use this Single Cell Li-Ion Battery Charger (MCP73833). The pins STAT1 STAT2 and /PG are an open collector outputs and it will be connected to low power LEDs as shown in the schematic. If I ...
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Setting up UART with STM32L4RGTx

The prompt here is to debug the issue with UART setup on the STM32 chipset. I've followed a couple of online blogs to understand and setup the UART interface. I want to transmit (only) a dataframe (...
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Driving a speaker with a 3.3 V processor

I got this design off of the internet and it is not working. I am trying to drive a PKLCS1212E4001-R1 with a MMBT2222A-7-F. The 3.3 V of the STM32L0 is not enough to turn on the BJT transistor. ...
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Microcontroller default state problem

I have a Microcontroller - S32K116 - 48 Pin IC. - Datasheet - Reference Manual I have a Voltage divider (for input voltage monitoring purpose) connected to the Pin 16 (PTC3) of the Microcontroller. ...
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309 views

Do the MCP23S17 GPIO pins need protection against latch up ESD within this circuit?

I wrote about this system before. I will focus my questions now on "ESD protection" direction. I have an SPI based system in which a Raspberry talks with a GPIO expender device using SPI ...
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ESP8266 with ultrasonic sensor, booting custom circuit and using gpio0, gpio2 pins for echo and trigger - would this set-up work?

I am designing a circuit from scratch with an esp12 module. For booting the esp8266, the GPIO0 and GPIO2 need to be pulled up to Vcc (3.3V) and GPIO15 needs to be pulled down to GND. I added to my ...
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159 views

How can I make a half-duplex UART to TTL converter for communicating to a servo with a HC04 and a HC126?

I have been trying to configure this circuit for some amount of time. I am using a HC04 chip and a HC126 chip. The HC04 is an inverter chip. The HC126 is a buffer gate. I found that for the servo ...
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118 views

Why is the MCP23S17 device getting too much hot suddenly and randomly Raspb 4A?

Circuit is a Raspberry Pi 4A SPI master node talking with one MCP23S17 device: datasheet. I'm testing the singlest circuit version in a protoboard. We are using A bank GPIOs for reading, and B bank ...
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89 views

EL wire and Raspi- is it safe and possible?

sorry for all of these questions, but I just want to check before I break anything accidentally :P I want to connect EL wire to my raspberry pi and control it via GPIO, but was wondering about the ...
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Can we drive an led from output port of TCA6424ARGJR IC?

I am using TCA6424ARGJR IC so from its output port 24 I need to keep an led, which glow when there is high. Can we drive an led from output port of TCA6424ARGJR IC? I have connected as shown in IMG.
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270 views

How to protect GPIO from back current? Diode? [closed]

After frying a Rpi with this montage 6 months ago: I followed advice from kind users here and modified the wiring to this back in February: It has been working fine for 6 months and suddenly ...
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Help replacing a physical joystick for motor control with a LabView program

I'd like to start by acknowledging the similarity of this question to this one, but I really need a more basic, step-by-step explanation. I am trying to help a student in my lab design a program to ...

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