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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MCU GPIO input pin state copying/buffering as another pin output in real-time?

I was wondering about the following: generally, in MCUs, are there typically facilities for "real-time" copying/buffering an input pin's state to another (output) pin? Typically, I would set ...
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Can I use a capacitor to smooth out 5v from an Atrix Lapdock USB to Raspberry Pi via GPIO? [migrated]

I have created the Raspberry Pi Laptop project using an Atrix Lapdock and Raspberry Pi 3B. I am wanting to do a overclock that might require an overvoltage. Can putting a cap on the 5v pin that I'm ...
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Input pin of Microcontroller [duplicate]

I am using this S32K142 microcontroller. Can someone tell me , how is the input pin of the microcontroller would be? Can someone tell me how, if a GPIO is configured as an input pin, how would it be ...
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Configuration of Used Microcontroller Pins [closed]

I am using S32K142 64-pin Microcontroller. I want to configure the IO pins in RUN Mode, Sleep mode and Reset mode. For used pins, say IO, I2C and SPI pins, output pins, please tell me what should I ...
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1answer
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Microcontroller IO pin configuration I2C

I'm using this Microcontroller S32K142 64 pin. In the reference manual, I can see a lot of pins which I assume to be Output only are mentioned as Input / Output. For example, the Microcontroller is ...
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RESET in Microcontroller [closed]

I'm using this Microcontroller S32K142 64 pin. I want to understand to whether the RESET pin is Input or Output from the Microcontroller. I checked the Microcontroller Reference Manual, it is given as ...
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How does a Microcontroller Start and What would be the state of GPIO pins during Initialization

I am using S32K142 Microcontroller 64-pin. I am finding some difficulty in reading the reference manual of the controller. I want to know how does the microcontroller initially starts and are there ...
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1answer
33 views

GPIO signals from Raspberry, read by Arduino

I'm working on a program on Arduino to control the Raspberry. My plan is using a button to make Raspberry Pi 4 switch on by pressed button (if i pressed a button for 3 seconds, raspberry will switch ...
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48 views

USB switch controlled by GPIO

I would like to find a USB extension cord with a switch, a bit like the picture below, but instead of a manual switch, I would like to control it by GPIO of RPi. I thought it would be easy to find but ...
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1answer
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ESP32's GPIO pins won't respond

I connected three LEDs to 3 GPIO pins in the ESP32. They used to blink as expect previously. But now, they don't. The code is as follows. ...
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DMA multiplexing on an STM32H7

Goal On my current project I have connected a multiplexer (4051) on 8 adcs that I read from a single pin on my stm32h7. I would like to sequentially change the three gpio's connected to the mux ...
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1answer
54 views

STM32 external 5V pullup

I have an STM32G031K8 Nucleo development board and was thinking about interfacing it's GPIO with an old BCD-to-Seven-Segment Decoder integrated circuit (SN74LS47N). This is a 5V part... and while I ...
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4answers
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Is it possible (with reasonable effort) to use ethernet hardware to provide point-to-point digital I/O bridge?

I'm interested in designing a "simple" circuit that would bridge digital inputs or outputs over a distance with relatively low latency. The idea is to take several pins from a GPIO bus like ...
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How to drive an open drain/collector?

I'm connecting a Digi XBee radio to a Kinetis microcontroller and would like to know how to control reset. The XBee datasheet describes the reset pin 5 as both input and open drain output: ...
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4answers
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What is the best way to add a LED indicator to an open-drain sensor that's read with a GPIO?

I'm designing a circuit around a QRD1113 optical proximity sensor. Its output is open-drain, and I'm implementing a 10k pullup. The signal is ultimately read by a GPIO on a RPI. I'd like to add a ...
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1answer
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Microcontroller States

I'm using this S23K142 Microcontroller - 64 pins. I just want to know (in general as well as with respect to this microcontroller) how many states does this Microcontroller have? By states I mean, ...
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1answer
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Microcontroller pin out configuration upon power up

I have this S32K142 microcontroller, in the 64 pin package. I have 2 SPI interfaces, 1 I2C interface, 2 UART interfaces, 6 ADC inputs, a few GPIO and PWM output requirements. My question: On initial ...
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1answer
57 views

Voltage to GPIO pins

Interested in Embedded Systems, I'm coming from Computer Science background. There is a thing that I can't get my head around for awhile about pins of GPIO. Let's say that we have a port which is ...
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3answers
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Getting glitches on GPIO using a MOSFET as a logic level converter

I need to connect an Event Detection pin (pin of the NXP NTAG 5 component) to a GPIO of the NXP i.XM6 processor. The problem is that the NTAG 5 pin has a logic level of 5V and the GPIO has a logic ...
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Protect ESP32 GPIO from ESD events, resets on inputs!

I'm working on a product that uses the ESP32 WROOM module. There are 6 exposed pins that user can touch, shown by the header attached. There is a piece of plastic that slides across a plastic ...
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4answers
990 views

My shift register is working when I use LEDs, but not a solenoid

I'm trying to operate a solenoid push pull motor with a shift register. It works fine with LEDs, but when I try to use the shift register to trigger my solenoid it doesn't work. I suspect it's a power ...
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1answer
81 views

Will these 100 ohm resistors protect my GPIOs from power surges?

I am designing a circuit for a microcontroller that has a few 3.3V GPIO pins. I heard from somewhere that adding small resistor of around 100 ohms in series with the GPIO, will add some additional ...
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1answer
48 views

SI5351 I2C clock generator breakout board not detected on raspberry pi 3

I've recently bought a SI5351A I2C breakout board on Aliexpress (This listing) for a project. I was trying to test the board using a simple breadboard, a couple of jumper wires and my raspberry pi 3 (...
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3answers
174 views

Monostable circuit with 1 hour high output

I want to build a monostable circuit (a circuit with one input as a pushbutton), that will output logic '1' when the pushbutton is pressed for one hour (with the least error possible) then go back to ...
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1answer
79 views

STM32L1 GPIO pin configuration - Power supply current increase due to pin with open-drain setup

Setup I have an STM32L151 mcu(application processor) and on its PB5 pin I have a peripheral (SARA-N3) connected. The requirements for the peripheral are that the pin is configured as an open drain ...
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1answer
40 views

ESP32-Cam GPIO remote control and video feed

Is it possible to control the ESP32-Cam GPIO from the web? Just like a "normal" ESP32 can create a website with buttons that turn on and off certain GPIOs Was wondering because I can't find ...
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3answers
103 views

Configuring the unused pin in CPU

I have just started designing the embedded systems. While designing the CPU and thinking from the reliability point of view I actually had few curiosities For the unused pins which are tied up to Vcc ...
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Level shifting 3.3v to Rail Voltage(up to 36V) using a bi-directional level shifter

I have the above circuit which is able to convert Vin to 3V3. Any IO pin of the MCP23S17 can be connected to D_OUT on the level shifter. D_IN can be used for either input or output signals. The ...
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1answer
78 views

Can I drive a motor directly with GPIO pins?

I have a Raspberry Pi Zero with a DC motor attached (directly) to gpio. According to the Raspberry Pi Foundation: The operating voltage of the GPIO pins is 3.3v with a maximum current draw of 16mA. ...
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1answer
46 views

STM32 Input Pin not working

i try to implement an input which is reacting on an high impedance 3.3V on PC14. My Configuration looks like this. ...
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6answers
1k views

Optocoupler with the same power supply

Often in MCU boards I see optocouplers even when the power supply is the same on both sides. Example: simulate this circuit – Schematic created using CircuitLab Here +3V3 and +12V have the same ...
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STM32 F103 GPIO software toggling too slow for 20 microseconds state change?

I'm designing an ESC for my hobby project but I got stuck on current chopping. I want to toggle a pin every 20 us and want to use a timer interrupt for this. On the oscilloscope I can see that timer ...
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1answer
77 views

Pressing one key in a button matrix reads all keys in that column

I'm using an MCP23017 IO Expander to make a button matrix (4x4). ...
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1answer
56 views

Pi Zero / GPIO Pins / +12V Power and Sharing Ground

I need a sanity check on my schematics before I pay for JLCPCB to make my PCB board. Goal: To have my Pi Zero fire a pyro charge in a model rocket. Setup: GPIO-20 Sends a signal to the MOSFET Gate, ...
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1answer
39 views

RaspberryPi touch sensor using transistor

I built the following circuit. When I touch the rogue transistor base wire and GPIO is outputting, the LED lights up (still not quite sure why, so if someone could explain this, that'd be helpful, too....
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3answers
88 views

Low resistance current limiting on GPIO pin

I'm trying to find a good solution for protecting the GPIO pin of an ATmega32u4 in short circuit conditions. Normally I would just use a simple resistor but that isn't the best option for this use ...
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1answer
47 views

Can you control a motor's general speed by oscillating from 3.3V to 0V?

I'm doing a project where I will take a Raspberry Pi Zero and build a model RC plane with two small DC drone motors. The frame of the plane houses a battery, the Pi Zero, and the two motors (in the ...
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3answers
122 views

Can a raspberry sink 5V

I'm using a raspberry pi to program an atmega328p. During my tests I was using 3.3V to power the avr and it was pretty straightforward, whenever a program is about to be written I pulled low pin 1 (...
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1answer
47 views

Input impedance of GPIO pins vs. current protecting resistor

Novice here. I have read that the input impedance of GPIO pins on a microcontroller might be in the order of 20 megohm. I’m trying to understand why we then might need a current limiting resistor with ...
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1answer
73 views

GPIO pins unintentionally all high on custom PCB (Arduino Due MCU - ATSAM3X8EA)

I made a custom PCB, using the ATSAM3X8EA which is the same as for the Arduino Due board. When I connect the power (the two holes on the far right), even before uploading any code, the LED (PC25) goes ...
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3answers
81 views

Basic Questions About a Simple Circuit (GPIO-Controlled Relay on RaspberryPi)

I want to control an 8-port Sainsmart relay from a Raspberry Pi (via the GPIO pins) and I'm trying to understand a couple of things about the suggested circuit for integrating the two. Here is the ...
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1answer
133 views

Unable to toggle an LED with STM32 Blue Pill

I'm a beginner, and I'm using an STM32 Blue Pill board for the first time. I completed a basic tutorial on how to activate the PC13 pin (on-board LED), but now that I'm trying to get an external LED ...
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42 views

Pigpio control of SG90 servo is imprecise on Raspberry Pi

I'm in the process of trying to build a laser turret using two SG90 servos, a laser diode and my Raspberry Pi. I've come to realize that the pigpio library I'm using to control the servo seems a bit ...
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3answers
110 views

Trying to understand push-pull output mode and open-drain output mode in a MCU's GPIO pin

I have a MCU (STM32H7xx) whose GPIOs, when configured as output, can be configured either as open-drain or push-pull. Before seeing this, I though that open-drain meant hihg-Z, however I don't see how ...
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2answers
95 views

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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4answers
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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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1answer
47 views

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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1answer
58 views

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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1answer
41 views

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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37 views

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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