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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GPIO button to control backlight on PiTFT

I've got an Adafruit PiTFT with the buttons on, so I have the potential to use the 4 GPIOs wired up to the buttons to control stuff. Now I followed the helpful tutorial, and have gotten the ...
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37 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 ...
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23 views

RPI with GPIO connector AND micro usb Power supply?

if I use both the GPIO connector and the micro usb does this double the Amper value and the voltage value or only the amper value ?
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34 views

Setup a led that blinks via php server

I wanted to blink or just lit up an LED on my Pi GPIO pin via a server/website. I've the resources like Pi, LED, php server etc. I just don't know how to code to connect my Pi to server and control ...
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38 views

Where to get / how to build a 50" / 1.25 m. long GPIO cable

I want to connect my 433.92MHZ transmitter to my Pi. The problem is, it's 50" away from my pi, and the only cables I can find online are 20 cm (8") long cables. I've thought about creating the cable ...
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32 views

How to get the state of a GPIO pin bash

how do I get the state of a pin and store it in a variable in a scipt?
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44 views

echo: write error: Operation not permitted

Running as root user yet I'm still not permitted to use this: echo "21" > /sys/class/gpio/export echo "out" > /sys/class/gpio/gpio21/direction echo "0" > /sys/class/gpio/gpio21/value
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32 views

how to interface raspberry pi and plc

am doing a project on controlling the plc by using raspberry pi. any one please suggest some sample coding and tutorial regarding this project. am already finished a coding part to connect a control ...
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38 views

/sys/class/gpio values only working if python gpio script was used before

i have a problem with the gpio sysfs files. when i use cat to get the values of a gpio pin it will always show 0. but after using a python script ( ...
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34 views

How to get the temperatur of 2 sensors in java, using an extension board?

There are several questions about getting the temperature but non of them covers a solution for java. I want to build al little weather station in java to gett temp values, unfortunatly i am not that ...
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56 views

Control GPIO from outside home network

I'm not exactly the most knowledgeable on the server-side aspects of how this kind of thing should/would work, but I do tend to pick things up pretty quickly. I've played around with WebIOPi and a ...
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61 views

Arcade buttons on GPIO, multiple buttons on the same ground pin

I have noticed that while hooking up arcade buttons to the GPIO set on the model b board that along with the joystick I should be able (by assigning certain GPIO pins to ground) to connect 7 other ...
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30 views

GPIO affected by audio playback

I recently found the PiFm project which sends a FM signal through a GPIO pin to effectively create a FM transmitter out of the Pi. A problem arises when you do a normal playback of a .wav audio file ...
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67 views

What GPIO pins are required to Power RPi? [duplicate]

We are using Raspberry Pi Model B: We used USB connector from PC - confirmed output - 5V, with 2 leads: Connected +5V to Pin 2 Connected GND to Pin 6 on connector - Inserted Ethernet cable ...
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2answers
44 views

How to bring out Status LEDs to be available on enclosure [closed]

We have developed a product based on Raspberry Pi and currently designing the enclosure. To enable users to understand the status of our device we would like to provide two LEDs. These LEDs would ...
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1answer
98 views

Looking for Raspberry Pi pinout image map showing all components

I'm looking for a link to a picture of a Raspberry Pi that has HTML pop-ups (mouseover and it tells you exactly what everything was depending on what you mouse was over). I can't remember what ...
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17 views

Raspbian crashing after servo.stop_servo()

I have a servo connected to my RPi and I try PWM.Servo's capabilities. The program below does what it should - but after execution it crashes system (it doesn't respond to any input, no animations, ...
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46 views

Powering multiple full-size bulbs

I'm working on a Pi project where I will need to have 4 lightbulb turn off and on based on schedule. The programming aspect is no problem but I'm guessing the GPIO pins are not powerful enough to do ...
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63 views

Connecting a bluetooth module to GPIO?

I got a bluetooth sensor from this Chinese company. Model is BC417. The module has six pins: KEY RXD TXD 5.0 3.3 GND I'm totally newbie about GPIO and sensors, only got that module and a few ...
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35 views

Raspberry Pi RetroPie GPIO Shutdown

I'm trying to make an arcade cabinet with my Raspberry Pi and I want to make a physical shutdown button for it. I can do this with the GPIO, I even wrote a python script to do it: import RPi.GPIO as ...
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73 views

Pro's 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 ...
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24 views

How to develop for Mikroe's click boards with free software only?

Hardware offer for the Raspberry Pi When looking for sensors, actuators etc, that are easy to use, one can spot that a Raspberry can host a Pi click shield - extension board for Raspberry Pi® with ...
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2answers
41 views

What servo motor and mechanism to move the whole Raspi, its camera and case?

I know there is an interesting Pan & tilt from openelectronics but my project is to move (to pan only) the whole raspi and camera with its waterproof case (# 500 gr) It 's for an outdoor site. as ...
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46 views

May I connect directly to GPIO headers without stripboard

I wish to install a thermo and a humidity sensor on my Raspi but I have no place for a stripboard or veroboard in my waterproofcase. So I would like to know whether I can connect them directly on the ...
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34 views

Some help on GPIO

Hi guys I would like you to tell me how to control 2 fans mounted in parallel from GPIO pins. I saw some electric diagrams using NPN transistors and protecting resistors/led but I can't really figure ...
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34 views

Debugging problem with GPIO serial pins

I've been trying to run a port of a small RTOS called ChibiOS on my Raspberry Pi, and am having trouble with the serial communications. Specifically, when I use a UART connected at 3.3V to the GPIO ...
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388 views

What are the usage of extra available holes in model B

Despite some research on the web, I cannot find the options available from these "opportunity" holes on the Rpi. I probably do not use the proper words to identify them. What is the name for this ...
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48 views

Pi4J - Changing GPIOs from and to Input, Low and High

I am trying to create something which uses Charlieplexing, and to use it, I need to be able to turn GPIO Pins to and from different states (Low, High and Input) from what I understand from this video: ...
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111 views

Live video streaming embedded in a web page [closed]

I have created a web page to have both live video streaming and some button controls to control the robotic arm interfaced to the RPi GPIO pins. For button controls, I used php coding. The php coding ...
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2answers
112 views

Power the Raspberry Pi via the 5v Pin

I tried to power my Raspberry Pi via the GPIO header, but it didn't work. I powered it with exactly 5v, but it won't boot, but the Status LED "ACT" is on. It's darker then normal, but it's on. I think ...
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92 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 ...
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40 views

How do you use the GPIO status registers? (e.g. GPEDS0)

I'm having some trouble trying to figure out how to use the GPIO status registers. These are used to set up monitoring of some event (e.g. GPIO input rising, falling, etc.) and then you read the ...
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78 views

GPIO.add_event_detect fires callback multiple times and on wrong signal edge

I'm trying to make an interrupt based matrix keypad reader that is loosely based off of this library. However, I'm getting some really weird effects when trying to use GPIO.add_event_detect in that: ...
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48 views

Transistor or optoisolator when dealing with the GPIO pins and an external power source?

I am using the pi as a switch to short the pins on my motherboard to turn on my computer. I see many people use an optoisolator to do this to protect the board. What purpose does the isolator serve as ...
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49 views

L.E.D controlled by IF STATEMENT from variable

I want to control some L.E.D's through the GPIO ports depending on the value of "variable1" which will become a raw input. The problem is, if variable1==70 then both led 12 and 16 with light, but only ...
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47 views

How can I control the PWM via the sysfs

I want to set the PWM for some tests with a tricolored LED. I want to be able to set it up via the sysfs interfaces but I'm having a very hard time finding any information on how to do this. What is ...
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52 views

I2C with zener protection isn't working

I wanted to put some protection on my PI's pins and chose the zener voltage protection one, as described here. I used TZX3V3A zener diodes and 330 ohms resistors. Like this : Then i tried to ...
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46 views

Generating CW from GPIO

I'm working on a project whereby I want to use the Pi to send some morse code (CW) over FM by feeding the CW signal into the mic input of a handheld radio I've stripped down. The idea stems from this ...
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83 views

GPIO pins are always HIGH

I recently have started delving into using the GPIO on my raspberry pi and when I got to the input section of adafruit's tutorials I noticed something wrong. For some reason when I execute the python ...
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129 views

How to use 2 x MCP23017?

I need to control 32 L.E.D's individually, now looking through the forum, the common solution is to use MCP23017 chips, as they can control 16 l.e.d's. With that in mind, I would require two chips. ...
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Cant get GPIO input working

I have my Pi set up using a Powered USB Hub. I have followed all the directions to create a mini arcade following the Adafruit tutorial. But none of the controls on the right side of the board work. ...
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43 views

multiple PWM for led control

I'm creating a musical instrument based on capacitive sensors and I want to add some color to it. I would like to use PWM controlled LEDs because I want to make them dim and fade away nicelly. My ...
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1answer
25 views

Logic State non-responsive

I need the raspberry Pi to respond to some buttons. I'm writing this in Pure C, using the wiringPi library. As such, I thought it prudent to use the gpio utlitily to make sure my pins were sane ...
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3answers
96 views

Control 18 LEDs individually? (17 GPIO pins)

Note: I have read Controlling many LEDs with few GPIO pins, but I can't buy additional parts (Degree project) The end result is to make a noughts and crosses grid with 2 LEDs per grid cell. This ...
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49 views

Analog to Digital converter

Can I connect a ADC0804LCN to a raspberry pi ? http://pdf1.alldatasheet.com/datasheet-pdf/view/77309/INTERSIL/ADC0804LCN.html
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24 views

Can the GPCLKn be used to provide an accurate clock signal for external microcontrollers and logic?

I have a hardware project based on an AVR microcontroller which must be clocked at 13.875 Mhz. The crystal for this is relatively expensive and quite difficult to obtain compared to the other ...
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76 views

Can't read/write to GPIO as non-root after export

This is driving me crazy. I do this: cameron@raspberrypi ~ $ gpio export 18 out Then here's the output of sudo ls -lL /sys/class/gpio/gpio18: -rwxrwx--- 1 root gpio 4096 Mar 8 10:50 ...
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90 views

Disable i2c in Raspberry Pi

I want to disable the i2c in raspberry pi, so that I can use it as GPIOs. I commented the lines in the /etc/modprobe.d/raspi-blacklist.conf, but not working.
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181 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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85 views

C and C++ Library and where is it located actually?

I'm trying to understand a few simple blocks about programming the Raspberry Pi. My questions are as follows.... I've work on a number of micro-controllers out there and have always used their ...