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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52 views

Would a capacitor between base and emitter make relay amplifier less noisy?

I have a single transistor relay amplifier driven by GPIO output of Raspberry PI. The amplifier works reliably and is not causing any immediate problems. Still, if I leave the relay flipping on/off ...
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1answer
29 views

How to use analog mode GPIO pin(not ADC input channel) for ADC?

I want to use a GPIO pin which is configured to be "Analog Mode" for ADC. I am working on STM32L073 series microcontroller. The pins with ADC input channels are used already. So I need to choose ...
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AT91SAM7S512 Oscillator, GPIO, & Reset questions

I just need some clarification of my circuit Oscillator: So for my circuit I want to be able to program it via USB, the datasheet gets a bit confusing to me tho. If I read the datasheet correctly I ...
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42 views

zero cross detection using linux GPIO in C

I am trying to make an AC dimmer and need zero cross detection using GPIO in C, I am using beagleboard. I have seen others using python on RPi so it should be doable but, it seems that GPIO reading ...
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1answer
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What is the use of 5V pins on Raspberry Pi GPIO?

On a Raspberry Pi, GPIO pins are 3V3 tolerant. And there are two 3V3 pins that we can use to play with GPIO (driving LEDs or sensing Buttons). But what is the purpose of the two 5V pins? edit: I am ...
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Can I drive 3.75 V / 370 ohm coil relay from Raspberry PI GPIO output?

I have discovered that there are relays like these available on the market that trigger at 3.75 V and have coil resistance above 370 ohm. I assume this would mean about 14 mA or about that might be ...
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2answers
97 views

What makes a input GPIO pin so sensitive?

I know that an input pin has a high impedance, but how a high impedance makes such pin be so sensitive? According to https://forum.arduino.cc/index.php?topic=454553.0 -- #4 mentioned If the input ...
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6answers
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Is a pull up/down resistor really necessary?

Logical reading (1 or 0) of a micro-controller input GPIO pin may float if it is neither connected to VCC nor GND; someone said it is because of surrounding RF interference. When a floating GPIO ...
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1answer
70 views

Routing signal and power lines using MCU

I got an MCU (STM32F103C8T6) and a special device The device has 2 main lines of interest: ID and VCC. The VCC is 3V3 tolerant and takes around 100-250 mA depending on mode. And ID is used for ...
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Can I use a voltage regulator to bring high voltage down to 3.3V GPIO input for ESP32?

I have a button connected to the power rail of my project and I want to know when it's pressed with an ESP32 chip. Since the input voltage (6.5V to 15V) is higher than the maximum rating of the ESP32 ...
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2answers
60 views

1-channel GPIO from industrial PC over RS232 port

I am ordering a computer based on 4x4-R1000V motherboard (Ryzen Embedded, https://www.asrockind.com/overview.asp?Model=4X4-R1000V) for an industrial application. I need a 1-channel GPIO (0 for zero, >...
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RFM69 hat for RPI get stuck because of noise caused by missing ground

I built a RFM69 hat for a Raspberry Pi 3 B+. It works perfectly as long as I do not use the GPIO to switch on the relay that drives a solenoid valve. Unfortunatelly a lot of times the switching cause ...
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6answers
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Circuit to limit a set of outputs so that only one is on

Background: I have a set of irrigation control valve solenoids (24V ac) that I control via a set of mechanical relays with the GPIO pins of a microcontroller (ESP32). The power supply does not have a ...
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1answer
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ESP32 - Can I safely use GPIO ADC2 pins for non-adc use while using WiFi

According to ESP32 design guidelines; ADC2 GPIO's should not be used when using WiFi due to conflicts. (or used with restrictions) This affects GPIOs 2,12-15 and 25-27. Suppose I use don't use any ...
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1answer
92 views

Two switches and two LEDs using 8051

I am trying to work around a circuit and my requirement is as follows: - There are two inputs and two outputs. Each input controls an individual led. I am writing a code for this requirement using a ...
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1answer
38 views

GPIO Button setup with switching power supply

I have a small board with 8 GPIO's, I previously had 4 buttons connected thus used 4 as inputs and 4 as outputs. I use a 10k pull-down resistor for each button. I don't have a resister pre input to ...
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95 views

Microcontroller vs Microprocessor [Driving External Hardware] [duplicate]

I went through a video on Youtube [2:42], that described "key difference" between a microcontroller and microprocess, apart from other differences, is that "microcontroller has a strong I/O capability ...
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1answer
85 views

Running a N channel MOSFET from 3.3V MCU

I am trying to run a low side switch with the 3.3V GPIO output of the Raspberry Pi (3.3v MCU), and for the particular transistor I’m using (IRF520) the 3.3V is barely enough to turn it on - is there ...
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1answer
47 views

PWM Mosfet (and help identifying the right one)

I am building a project to control a 12 V, 10 A heating system from a Raspberry Pi. I have identified that I need to use a MOSFET transistor and I will control the output by using pulse width ...
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1answer
113 views

Boosting current to trigger 3v relay

I should start off by saying that I'm really new to this electronics engineering thing and I really have no idea what I'm doing. I am working on building a display stand that turns some LEDs on/off ...
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0answers
19 views

How do I model CDM in Hspice

I am trying to model CDM (250V)so that I can check my RC clamp circuit using Hspice . If you have any model please share .
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2answers
71 views

How to calculate current into GPIO pin after voltage division

I want to use my Raspberry Pi as a remote power management device to turn my home server on and off. I would also like to monitor whether the server is on or off by using the power LED pins on the ...
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1answer
74 views

why the voltage at the gate terminal is 1.8V irrespective of the 3.3V pull up? [closed]

[![the output of my GPIO is 1.8V which is pulled up to 3.3V using a 4.7K resistance and that gpio is connected to the gate terminal of a P-channel mosfet, when i measure voltage across the gate ...
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3answers
67 views

Driving RGB LED using GPIO

I am trying to drive this RGB using the GPIO of STM32F072. The GPIO can source around 25mA and the LED consumes around 20mA. Would there be any issues?
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Using internal pullup, pulldown resistors to find floating IOs

I want to find at runtime if a GPIO is floating (nothing connected to it). I assumed I'd find tons of answers on Google, but maybe I'm searching wrong. My approach has been to: enable the internal ...
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3answers
160 views

Microcontroller - GPIO [closed]

I have a digital input to a microcontroller in the +5V Domain. This digital input is connected to the Microcontroller. The output of the Microcontroller is connected to an LED Initial LED Logic : ...
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1answer
21 views

Eagle: Alternative to Pinswap for GPIO expander

I'm working on a PCB which is basically multiple MCP23017 GPIO expanders driven from I2C. As I layout the board (in EAGLE), I frequently find places where using different IO pins would avoid vias and ...
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1answer
84 views

Driving NPN with Raspberry Pi

When driving an NPN transistor using the GPIO output on a raspberry pi I assume no protection is needed on the GPIO side of the circuit? So nothing would really be needed beyond this to drive the ...
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4answers
357 views

Why would you enable pullup for a GPIO pin in push-pull mode?

In this STM32L486xx HAL User Manual (note: 36 MB!) is an example for GPIO configuration to power an external LED on page 53. The code lines that are confusing me are these two: ...
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1answer
133 views

fpga gpio pins as uart pins (tx and rx)?

I am trying to use fpga de2115 and (ftdi ft232rl usb to serial) to communicate with pc. Can the tx/rx pins from the adapter be connected directly to the fpga gpio pins? The board has rs232 port , but ...
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0answers
41 views

BeagleBone Black Pins Stuck on High

I have written a function in C++ that uses the kernel mmap function to toggle the value of GPIO pins. This works fine for many other pins, but I tried to use it on ...
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1answer
65 views

Emitter follower for parallel LED switch

I’m trying to confirm that the solution posted in https://electronics.stackexchange.com/a/60868 will work for my application. I have four yellow LEDs with a 2v drop (yellow) and 30mA max current I’...
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1answer
45 views

NodeMCU GPIO pin interrupt [closed]

When using NodeMCU, I want to toggle the state of GPIO pin, using a physical switch. When the switch is pressed, the switch state should toggle from low to high, or high to low. I know I need to use ...
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0answers
42 views

ESP8266 vs ESP32 and WakeUp vs Reset

Maybe it's my fault but I kinda dislike the design of the ESP8266 when it comes to wakeup from deep sleep via an interrupt. AFAIK (without an external circuit) the ESP8266 can not distinct between a ...
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2answers
85 views

TMS320F280049C: Unwanted pulse on GPIO during power on/off

I'm using the TI TMS320F280049C microcontroller. While testing its GPIO behavior during power on/off, I found a high to low transition on GPIO pin, on every power on/off. I'm checking the waveform ...
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1answer
119 views

Does the drive strength of a GPIO pin alter with change in temperature?

In low temperatures the functionality of the I2C is being affected, but the slave is working properly and the temperature is also within limit of slave. For that reason I suspect the drive strength. ...
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1answer
56 views

Strange STM32L476RG GPIO behaviour when leaving STOP mode 2. Is it a silicon bug?

Before I enter the stop mode 2 I save all the GPIO MODER, OSPEEDR and PUDPR registers, configure pins as analogue (to save some power) and enter the STOP mode 2. When I exit the stop mode (I use RTC ...
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1answer
38 views

Simulating pad button press with GPIO rPI3

So, i have very limited knowledge when it comes to electrical components. I have a decent amount of programming experience however. I am trying to simulate a button press (big middle button in linked ...
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2answers
136 views

How to connect MCU input pin with LED and Button?

I want to connect a LED and Push button on the GPIO input pin of a MCU, STM32F103 so that when the push button is pressed then the state of LED indicates the button is pressed. Is it possible to ...
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1answer
109 views

Digital inputs problem [duplicate]

I'm designing a digital I/O module which isolated with optocouplers. I'm done with the outputs, but having a confusion about input side. I will have some switches and sensors to read as inputs, but ...
3
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1answer
468 views

Why should I use a pull up/down resistor for a GPIO output pin?

I know there are lots of similar questions and read them, but I need a simpler and clearer answer. I understand why and how to use a pull up/down resistor when using a button (GPIO input). But while ...
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1answer
146 views

GPIO over voltage input protection

I want to design a circuit that can protect GPIO of the microcontroller from high voltages.the GPIO connects externally to mechanical switch. So my approach was to use zener diode to clamp the high ...
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3answers
86 views

Single GPIO for optocoupled input and output

I want to use a single GPIO pin as optocoupled input and output (at random discretion). Will the following scheme work for any possible combination of input and output? Especially when optocoupler 1 ...
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3answers
202 views

Sinusoidal wave output from a GPIO

I think the question is not particularly MCU/board specified but I will be trying it on STM32F4-DISC board. I was thinking of how to output a nice sinewave from a normal GPIO output pin, but I was ...
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3answers
97 views

Using GPIO to control multiple leds via transistors

I'm trying to control 16 LEDS with the GPIO ports of a Raspberry Pi using transistors. All 16 can potentially be illuminated together. I'm trying to figure out if I can use approach B to save PCB ...
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2answers
84 views

Atmel AVR cutting down the power

This might be a straight forward question: An AVR gets its power from a regulator which can be turned off with a digital low level input. However on a spike (digital high followed by digital low) the ...
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0answers
37 views

Configuring GPIO directions for I2S interface

I am working on integrating a WM8731 audio codec chip with an AM335X processor. This is my first time working with I2S and I want to make sure I understand it correctly for configuring GPIO directions....
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0answers
73 views

Flaky GPIO on ESP8266, how do I solve it?

I have an ESP8266 where I took one of the GPIO pins, configured the pullup on the input, then connected it to one lead of a 15m cable and the other lead to the ESP8266 ground. The problem I have is ...
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1answer
60 views

safe negative voltage divider to GPIO pins

this question comes from this other, trying to implement the folloging circuit to measure a -3V battery pack (2xAA) (I've to measure in that way, cannot swap or move GND): Digital PIN 6 will be set ...
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1answer
52 views

stm32cubeMX difference between Gpio_output and Gpio_input [closed]

I will use L476RG to connect with a battery power board, battery board will use two Gpio ports to ONLY send out info, such as battery is full, battery is in charge, and so on, now the question is, in ...