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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140 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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1answer
4k views

Controlling a brushed motor ESC from the Raspberry Pi

I've tried solutions from similar problems, but none of them gave me any usable results. I'm trying to control those http://www.ebay.com/itm/311177661450 electronic speed controls (ESCs) with ...
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2answers
275 views

Which GPIO pins on previous modela are equivalent to those on the B+ model?

The problem I am having is that the B+ model has more GPIO pins than previous models. I'm not sure of the exact number, I've not counted and I don't think it matters for my questions. You can see ...
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2answers
88 views

How to know if Raspberry is running

I'd like to implement an electronic circuit to be able to restart my raspberry Pi when it has been shutdown (without plugging in and out the USB charger, which will obviously remain plugged all the ...
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5answers
15k views

Can I use a DHT22 as a temperature sensor for my Pi?

Is it possible to use a cheap temperature sensor such as the DHT-22 with the Raspberry Pi? I have found Arduino drivers for this and many similar things, and would be comfortable porting the code to ...
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2answers
13k views

Driving PWM output frequency

After many hours of fruitless searching and reading, I still didn't have a complete understanding of how and why to output specific frequencies from the hardware PWM pin on the RPi without using ...
8
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1answer
6k views

Reading GPIO states using C

I've implemented this example to familiarize myself with basic GPIO programming in C. The code demonstrates how to write to GPIO pins but does not explicitly state how to read the state of pins. I ...
6
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4answers
21k views

RPi GPIO as a high-speed square wave generator

I'm trying to make RPi generate high-speed square wave through its GPIO pin. My code controlling GPIO output is based on this article The essential part of my code is the following: speed = 1000000;...
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3answers
9k views

Maximum current on each GPIO pin for Raspberry Pi 3 Model B

Anyone knows what's the maximum input/output current for the individual GPIO pins? Perfectly fine if someone is able to point me to the Broadcom BCM2837 datasheet, which I for some reason, cannot ...
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4answers
26k views

Raspberry PI and fingerprint scanner

How can I make Raspberry PI work with a fingerprint scanner like this? I found something for Arduino only (http://learn.adafruit.com/adafruit-optical-fingerprint-sensor) Are there any tutorials for ...
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3answers
18k views

Plug a 5 V fan to GPIO 1 and 2

Regarding to the following picture, I understand that I can plug a 5 V fan by plugging it in between pins 1 and 2. Is this right (+ on 1 and - on 2?)? My need: Plug a 5 V fan to run all the time the ...
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1answer
2k views

Zero-crossing activated relay

How could I go about programming a switch (based on solid-state relay or a triac) that triggers on zero-crossing power? For these not familiar with the subject: Switch 230V power on, when the sine ...
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3k views

What is the nominal GPIO Pin Output current?

What is the RPi GPIO Pin output current? I assume it's more than 10mA since it can drive LEDs without any problem but what is the spec?
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What is the best way to increase digital I/O lines on Pi?

In one of my projects I need six PWM outputs, 12 digital I/O and around six analog inputs to be controlled by a Raspberry Pi. What are some of the best options available to increase the I/O capability ...
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3answers
10k views

Is it possible to connect an LED directly to the GPIO of the Pi?

I was wondering if it is possible to connect an LED directly to one of the GPIO pins of the Pi? The reason I ask is that, I have read from many sources that if I am not using some sort of break out ...
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3answers
3k views

GPIO pin voltage is too low to energize relay

I am trying to toggle a small relay on and off. I have connected a GPIO pin and GND directly to the relay. I can hear the relay clicking, when I set the GPIO pin to HIGH. However, the relay only ...
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2answers
16k views

Automatically run a program as root for GPIO?

I have a Raspberry Pi running Raspbian that I want to auto-login and then automatically run a program that uses the GPIO as root. I have auto-login working as per this website. What is the best way ...
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1answer
572 views

GPIO Temperature Sensor not Recognized

I recently tried to connect a temperature sensor (http://www.adafruit.com/product/381) to my RasPi via the GPIO, with a 4.7k (2Watt) resistor connecting the power and data (Source: http://www.cl.cam....
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1answer
1k views

gpio /value file appears with wrong permissions momentarily [closed]

My son is implementing a server on a raspberry pi that allows control of the gpio pins via a network connection. He has discovered a very strange bug. First, the OS being used is raspbian, a version ...
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1answer
5k views

8x8 matrix of buttons

It is possible to connect 8x8 matrix of buttons to the Pi using 16 GPIO pins, 8 for rows and 8 for columns? What are possible alternatives of doing this?
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4answers
5k views

How to control a Traxxas XL-5 ESC directly from the GPIO?

I am trying to control the ESC (Electronic Speed Control) of my Traxxas RC car with my raspberry pi (rev.2). I have been looking through the internet and while I can find some projects that seem to ...
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1answer
11k views

Do all GPIO pins have a internal pull-up/pull-down resistors?

So question is: Does all Raspberrys GPIO have a internal pull-up/pull-down resistor which can be enabled from program, in my case Java language with PiJ4? I have Raspberry Model B+.
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RPi as a Sound Level Meter?

For my daughter's science fair project (Computer Science and Math category), she'd like to use the RPi to go around and measure whether different loud sounds are above the threshold of pain and are ...
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3answers
7k views

How to detect whether there is voltage between two points via GPIO?

I'd like to detect whether an external device is switched on or off. I found two pins where there should be 5V between in the first case, but the voltage may vary a bit and I don't wont to break the ...
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4answers
29k views

How does python GPIO bouncetime parameter work?

I have a simple Python script that is observing two GPIO pins, I've set the bouncetime parameter to 500ms, but I get multiple (almost always 2) calls to my callback, usually 3 or 4 ms apart. This is ...
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3answers
6k views

Connect sim800 to Raspberry PI (RX, TX)

I've been trying to connect my sim800L to my Raspberry pi 3 model B (rasbian) but without success... I'm at the very first step, and since I'm new to Raspberry pi, I don't understand very well how it ...
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2answers
4k views

How fast can GPIO pins toggle?

I'm currently using Python's RPi.GPIO module to toggle some pins, and I want to know how quickly it can do this. I need the pins to be toggled on the schedule of a ~50 mhz FPGA clock, which I'm ...
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3answers
250 views

Multiple GPIO Buttons

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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1answer
129 views

Raspberry Pi 3b+ do not detect DS18b20 on 1Wire

Problem: The new raspbian kernel does not detect the DS18b20 sensor over the 1wire bus. This is due to the Device Tree that was added to Kernel 3.18.8 What hardware used: Raspberry Pi 3b+ Kernel: 4....
2
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1answer
248 views

Lirc - interference from power line

IR remote stops working after switching lights (or other electrical equipment) in the same room. The service of the lirc returns to normal after some time without doing anything. There are ...
2
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1answer
1k views

How to get MCP23s08(8 bit I/O expander) working with GPIO on Raspberry Pi?

I have an MCSP23s08( 8-bit SPI I/O expander) and a Raspberrypi. Does anyone know what I need to plug where to get them to communicate?I want to read data from MCP23s08 and write it to GPIO pins of ...
2
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2answers
2k views

GPIO input connected to garage door button

I would like to connect the garage door's button to a GPIO input on my Pi. I want to be able to trigger actions when someone pushes the button. I am able to read the status of a basic switch using ...
2
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1answer
673 views

Is there a way to make a RP3-B act as a USB gadget/periferal?

I have a Raspberry Pi 3 (Model B) that I would like to act as a USB gadget or OTG peripheral. Some sources state (without proof) that the USB_ID line is not connected properly, to allow any software ...
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1answer
2k views

Needs some ideas to trigger silicone rubber buttons

I would like to remote control the HVAC in the house. As a first not so intrusion attempt (rather than install relay and everything), I'm thinking to attach some GPIO pins to the controller panel and ...
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1answer
6k views

How to get pin addresses on a MCP23017

Recently I purchased a few MCP23017. I've been reading up on them and I've gotten a few lights to turn on and such. I am having a problem trying to understand how to figure out the register address ...
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2answers
3k views

Permissions on /dev entries

I'm waiting for my Pi. From reading the tutorials and books on doing i/o on the Pi I'm getting the impression that linux makes entries in /dev on the fly, which is nice, but they're owned by someone ...
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3answers
2k views

rPi2 model B v1.1 smoke comes out near power port

I am trying to control 2 motors using the E-gizmo Motor driver shield but suddenly smoke comes out near the power port of the raspberry pi 2 so I immediately unplugged the power supply. After that, I ...
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1answer
6k views

Differences in GPIO between Raspberry Pi 2 B and 3 B

Is there any difference in the GPIO layout between Raspberry Pi 2 B and 3 B? If yes, please provide the differences.
3
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1answer
265 views

TMP36GZ/DS1822 Temperature Sensors not outputting any values

I am trying to connect a temperature sensor to my Raspberry Pi using this tutorial for Windows IoT Core. I have connected all of the wires and MCP3002 correctly, but I cannot read in any values from ...
3
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1answer
393 views

How long to wait after shutdown to cut power

I am working a problem that seems to be fairly popular with the Raspberry Pi community. In essence, I am designing a circuit that will utilize a DS3231, a 555 timer, and a load switch to cut power ...
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2answers
2k views

Raspberry pi GPIO extension

I recently started using rasperry pi. I am trying to do some home automation and controlling toy car motors. I am able to control the motors and 2 plug points. I wanted to control more servo motors. ...
2
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2answers
666 views

Strategy for controlling one Pi's outputs from another Pi's inputs via network

Im trying to use two Pi's as a bridge to trigger a garage doors button from an automation system that uses its own GPIO. My thoughts where give them each a static address and script one to ssh into ...
2
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1answer
7k views

I short circuited 5v & gnd of Rpi

Accidentally I short circuited 5v & gnd of R-pi, since then my R-pi is not working. How can I make it start again by means of replacing some IC or power regulator or anything ? Please help.... ...
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2answers
1k views

How to operate a cooling fan using GPIO pins, RaspPi2

I have little to no experience with any form of computer software coding/editing but I have managed to get EmulationStation working (sort of) on my Raspberry Pi 2. I have a bought a fan and plugged it ...
2
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1answer
2k views

Force detection of GPIO device connection/disconnection

How do I force the system to detect a GPIO device has been connected or disconnected? For instance, I'm playing with the DS18B20 temperature sensor, and I noticed that immediately after connecting it,...
2
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4answers
4k views

Use RPi as a LIN Master to control slave nodes

I am trying to use the RPi as a LIN Master to communicate with a number of slave nodes on the LIN bus. I can send the correct bytes, starting with the sync byte of 0x55, and then the node ID, the ...
2
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2answers
2k views

/sys/devices/virtual/gpio dissapears after installing RPi.GPIO on Archlinux ARM

...tinkered a bit with GPIO and Piface Digital. It was all ok until I had installed RPi.GPIO via pip. After that the directory /sys/devices/virtual/gpio disappeared and never showed up again. I had it ...
2
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1answer
619 views

LED resistor question

I'm fairly new to electronics and I'm in the process of creating a IR Birdbox using a Pi Zero and IR Camera. I have a quick question regarding the correct usage of Resistors for IR LEDs (Or any LEDs ...
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4answers
583 views

Where exactly are these GPIO pins located on Raspberry PI 2 Model B?

I am having hard time understanding the Raspberry PI 2 Model B's PINOUT. I have RTC Module I want to use with my PI, but no matter what I do there seems to be NO response at all from RTC. I even ...
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1answer
579 views

GPIO Voltage tolerance for input

I have not been able to find the input tolerance on I/O pins, especially on the Input pins. If I apply a voltage 3.6v (3.3v +0.3) on an input will it be dangerous or is it ok ? Does somebody have a ...