Questions tagged [gpio]

GPIO stands for General Purpose Input Output and can be used to receive and send digital signals to and from simple electronics from the Raspberry Pi.

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25
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2answers
41k views

Power a 5V relay from GPIO pins

I have a bank of relays (5) that I'm looking to run from my Pi. I'm using 5V TE Connectivity relays, powered by Sparkfun's high power relay kits, which use a NPN transistor to trigger the relay. So ...
116
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9answers
307k views

How do I supply power through the GPIO?

I have seen some examples of people powering their Raspberry Pis by wiring a DC "barrel plug" style power supply to the 5V and GND GPIO pins. What considerations should be taken when doing something ...
64
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5answers
156k views

What is the maximum current the GPIO pins can output?

What is the maximum amount of current that can be pulled from a single GPIO pin? Does the maximum current decrease if current is being pulled from multiple GPIO pins? From my research, I've found: ...
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1answer
9k views

What are the Electrical Specifications of GPIO pins?

What are the Electrical Specifications of GPIO pins; current limits and voltage levels?
4
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1answer
4k views

How to use Arduino devices with Raspberry Pi?

I bought "RFID RC522" & "GY-NEO6MV2", and I need a useful guide for both of them in order to use them with Raspberry Pi 3 Model B. I also want to know if there is a guide or a course for using ...
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4answers
27k views

Raspberry Pi 3 model B "dtoverlay=gpio-shutdown"

To my /boot/config.txt on Raspberry Pi Model B I added: dtoverlay=gpio-shutdown,gpio_pin=3,active_low=1,gpio_pull=up Right now nothing happens when i shorten GPIO#3 with ground. What else needs to ...
1
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1answer
991 views

How to tap / tee / fork / stack the Rpi GPIO pins covered / blocked by a HAT / pHAT / bonnet?

I have a blinkt pHat that covers the entire GPIO pin array and I'm trying to trigger changes to the LED array after an external prompt. I expected to use a momentary switch connected to the GPIO pins, ...
104
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5answers
241k views

Can I use the GPIO for pulse width modulation (PWM)?

Can I use the GPIO as a pulse-width modulation output? If so, how would I go about doing it and how many concurrent, distinct PWM outputs can I have?
44
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7answers
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Access GPIO pins without root. No access to /dev/mem. Try running as root!

I've made a python script using the RPi.GPIO library. I need to run it without root but I get this error when running it with "python ./script.py": No access to /dev/mem. Try running as root! I've ...
48
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1answer
140k views

What are the min/max voltage/current values the gpio pins can handle?

I want to start using the GPIO pins but I am worried about short circuits or using too much amperage and frying my raspi. What are the Min/Max Voltage and Current values rasppi can handle? What is the ...
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2answers
585 views

Run the program in the laptop and use the raspberry gpios, PWM to control servos

I'm working with face tracking and I want to activate some servomotors depending the motion of my face. For facetracking I'm using, an usb cam, opencv and dlib. Now results the raspberry can't run my ...
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3answers
60k views

Can I get audio input through the GPIO

The Pi has a standard 3.5mm audio jack, but this cannot be used for audio input However, we've got a load of GPIO pins on various interfaces. Would it be possible to recieve analog audio into the Pi ...
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3answers
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Control Hardware PWM frequency

I'm using the hardware PWM output with wiringpi. It provides the function pwmSetClock that should make it possible to change the frequency. (https://projects.drogon.net/raspberry-pi/wiringpi/functions/...
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3answers
30k views

Why are some GPIO pins HIGH when the Raspberry Pi boots up?

I have an easy circuit wired up, with an LED connected to pin 18 on the BOARD reference. I run a simple program to put pin 18 to HIGH, which turns the LED on, and then a couple of seconds later, I set ...
8
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1answer
3k views

GPIO callbacks in any language

I know the linux kernel has a language agnostic GPIO interface through /sys/class/gpio which can be manipulated with echo, cat, etc. How can this be used to create event driven callbacks ...
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2answers
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Controlling many LEDs with few GPIO pins

I successfully completed my hardware "hello world" using this guide: http://www.raspberrypi-spy.co.uk/2012/06/control-led-using-gpio-output-pin/ Now I'd like to move on to bigger and brighter things,...
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3answers
1k views

Rpi UART control IR Remote HDMI switch problem

I've been reading about how to use the GPIO to toggle a button on a thing I've taken apart. It's like this: Amazon I watched a video of a guy using an opto-coupler, what are the basics here? I'm ...
12
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1answer
11k views

Raspberry pi GPIO input pins give random values

I've been playing a lot with the Raspberry Pi lately. But I have a problem. When I set up an input pin to check whether electricity is sent to it or not, it gives me rather unstable answers. A few ...
23
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2answers
18k views

How can I control a 12V motor? [duplicate]

I would like to control (switch) some 12V DC motors using the GPIO pins. I do not have (or want to use) an expansion board. Nevertheless, I think this should be possible using a transistor switch (and ...
2
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1answer
9k views

I2S Recording combined with I2S Playback

I have a Raspberry Pi Zero and I am using the Adafruit I2S MEMS Microphone together with the ADAFRUIT I2S 3W CLASS D AMPLIFIER BREAKOUT - MAX98357A. I did follow the two respective tutorials and I ...
2
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4answers
754 views

program my robot with python

initially my question was about how to fix my code. You informed me that usage of that python class will not work with my setup of one motor. I agree and I want to instead use the GPIO library to ...
2
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2answers
4k views

How to check if SPI is enabled and functional on Raspi 3b+?

I have run raspi-config and enabled SPI and also verified that /boot/config.txt contains the line: dtparam=spi=on However, when I run lsmod | grep spi I get the following: spidev ...
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2answers
535 views

How can Rpi use a matrix key pad to read multiple, up to 256 keys / buttons?

I would like to build an organ pedal board and use Raspberry Pi as signal processor. The pedal board will have 32 inputs, one for each key. I am planning to use magnetic sensors (like A3144), which, ...
149
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1answer
408k views

What is the difference between BOARD and BCM for GPIO pin numbering?

When using the RPi.GPIO library in Python you have to call import RPi.GPIO as GPIO and then GPIO.setmode(GPIO.BOARD) or GPIO.setmode(GPIO.BCM) What is the difference between these two options?
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3answers
24k views

What is the power on state of the GPIOs?

What is the state of the GPIOs when power is applied? eg High, Low, Hi-Z? Also does any OS change the state of any GPIOs when it loads? Hopefully not.
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2answers
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Pi as a USB client

I am looking for a way to have the Pi act as a USB client and masquerade as a flash drive. I have seen lots of suggestions, however most of them are old (1+ years) by now and vague/incomplete - I ...
10
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3answers
9k views

Creating halt/wake button?

I have rigged up a wake-from-halt button using pins 5 and 6. These two pins, when connected, will reset power and reboot from halt. I want to use this same button, if I can, to run a command that, ...
12
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3answers
31k views

How to output audio signals through GPIO?

Is there any way to output audio signals through GPIO and is there any disadvantage with this way?
24
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1answer
28k views

DS18B20 not listed in /sys/bus/w1/devices

I'm starting work on a fermentation monitor using the Adafruit temperature sensing tutorial, a RPi B+ running Raspbian, a 4.7 kOhm resistor and a DS18B20 to which I've soldered male breadboard pins. ...
5
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1answer
4k views

Do I need a current limiting resistor in series with a magnetic door sensor?

I'm building an alarm system and I'm using a magnetic door sensor, conected to ground and a pin of the gpio set up with an internal pull-up resistor. As far as I know, this means that the pin will be ...
6
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4answers
8k views

How can I control the red LED again

I just acquired the latest Pi-3. In the Pi B+ and Pi 2 it was possible to access both the red and green LED through /sys/class/leds/led0 and /sys/class/leds/led1. After setting up the Pi 3, I have ...
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1answer
685 views

How to use a stackable Rpi relay HAT to control 220V AC mains power?

So I want to wire two DHT22 sensors (5V) to a Pi and also control a lightbulb with 220V. As a plus this should be very compact and I don't want to solder or use breadboards/jumper cabling. I looked ...
45
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6answers
24k views

How to measure temperature?

What can I connect to the RPi to measure temperature? I think devices connected to the I²C or SPI would make most sense. Here is a question about DHT-22 and other 1-wire devices. But at this stage it ...
29
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5answers
32k views

Circuit to safely power-down Pi

I want to use my Pi as an XBMC server in the car. The XBMC docs say that you should always use the shutdown command before disconnecting the power. I've been thinking that it should be possible to ...
30
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4answers
34k views

How can I use I2C to talk to sensors?

How can I talk to digital sensors over the I²C interface? Hardware: Which pins on the Raspberry Pi's GPIO can I use? Software: What I²C libraries are available?
33
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3answers
38k views

Why is a resistor needed for LEDs?

While looking for a basic task to get familiar with the Raspberry Pi and its GPIO pins, I decided that driving an LED sounded simple enough. While investigating how to go about this task I've noticed ...
11
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2answers
17k views

PiGPIO Library Example for Bit-Banging a UART

The PiGPIO library http://abyz.me.uk/rpi/pigpio/index.html mentions that one of it's features is "software serial links using any user gpio". I take this to mean that you can use it to generate a ...
9
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2answers
2k views

How to detect what kind of HAT or GPIO board is plugged in - if any?

I am setting up some Raspberry Pis for use in demos to colleagues, in order to show off capabilities of the Pi itself, and of some of the add-on boards that are available. I would really like to be ...
11
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5answers
20k views

How can I wire this SD card reader to RaspberryPi?

I need to add a second SD card reader to my Raspberry Pi for the project www.samplerbox.org (the RPi will be embedded in a box, so I need a user-SD-card reader). Here is what I would like to use: ...
10
votes
5answers
15k views

How can I turn an GPIO to its alternate function?

I want to use the altenate function of GPIO 4 namely the GPCLK0 function. How can one set a GPIO to its alternate function? Many alternate functions are summarized here: elinux-wiki The best would ...
11
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3answers
15k views

LIRC won't transmit (irsend: hardware does not support sending)

I’m trying to control an IR HVAC unit in my house with a Raspberry Pi 2 and an infrared shield (see here: http://bit.ly/29iC0lr). I followed the instructions on the IR shield product page with tips ...
4
votes
3answers
6k views

Multiple GPIO Buttons vs Matrix Keypad

I've seen a tutorial here that shows me how to do this: But what I want to do is like this: I want to have multiple buttons and distinguish between them. The graphic I painted depicts the desired ...
2
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3answers
7k views

Power USB device over Raspberry Pi GPIO Pin

For an embedded system I need to be able to switch certain USB devices on a RPi on and off without physically disconnecting them. The whole setup will be in an enclosed casing. My idea now was to ...
9
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1answer
16k views

What are the ID EEPROM pins and what can they be used for?

I understand that it's a type of ROM, but is there more to it? How can it be used for?
4
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3answers
10k views

Is the gpio readall command compatible with RPi 4?

It's already a while since I got my Pi 4, but never used the gpio readall command until yesterday. I have run into an interesting error. pi@raspberrypi:~ $ gpio readall Oops - unable to determine ...
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2answers
1k views

Rpi3B SSD1306 OLED I2C Interface Problem

I know there are similar questions, but none of them helped me out. I have a Raspberry Pi 3 Model B Rev 1.2 and Raspbian 10 installed. I try to connect an 0.91" Oled display (Hardware Details) which ...
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2answers
139 views

Slight dip on the GPIO 5v line when LEDs are on

I have my raspberry pi set up to do two main things: control 16 LEDs via 16 transistors each connected to an out pin. The LEDs are collectively fed the 5V from the GPIO. power a chip also on the 5V ...
36
votes
1answer
71k views

Pros and Cons of a Pi Cluster?

I have seen a lot of posts asking how to build a "supercomputer" or cluster with Raspberry Pis, but I have found very little with the pros and cons of actually making a network of Pis. I am interested ...
31
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9answers
3k views

Libraries for interfacing with the GPIO

What libraries are available for interfacing with the GPIO?
29
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3answers
9k views

How can I use the GPIO pins as digital outputs?

I've read that the Raspberry Pi has a number of input and output pins. How can I switch them? (from Python?) What voltage logic? Do I need pull-up or pull-down resistors? Do I need to switch the pins ...

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