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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If I use a ribbon cable with my PiTFT, is there a maximum length?

If I wish to detach my PiTFT screen from my Raspberry Pi (Model B) using a ribbon cable, is there a maximum length of cable I can use to prevent latency issues with the screen? I saw in the PiTFT ...
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1answer
17 views

GPIO HW PWM @ 143Hz and 20-80% duty cycle, with WiringPi's gpio utility

I've tried to find the solution from other threads but they all seem to miss the point to a certain degree, usually going into kHz and MHz, or into the SW GPIO territory that I don't need. I have a ...
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2answers
40 views

How many buttons at once?

I own Raspberry Pi 2 B and I wanted to create something like Novation's Launchpad. How many buttons can I connect through GPIO at once?
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3answers
16 views

SPI library installation error

I want to read and write RC522 RFID by using raspberry pi. For that I want configure SPI communication. First I enable SPI in raspi.config. After that I tried to download SPI-Py package to enable SPI ...
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6 views

Running Deamon Involving GPIO on Pi [migrated]

I have a deamon that monitors various things using the GPIO ports. I have used python to write the code for this using the RPi.GPIO module. I would like to ensure that the deamon is always running, ...
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32 views

External Watchdog Timer For Raspberry Pi B+ using 555 Timer IC

I want to make a External Watchdog Timer For Raspberry Pi B+ using 555 Timer IC. I find a Setup for Arduino and its code... int pulsePin = 2; int led = 6; unsigned long lastHeartbeat = 0; unsigned ...
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1answer
116 views

Controlling Servos with a Raspberry Pi

I am not sure if this will break my Pi, so I decided to double check In this image is a simple servo connection, I am still learning how servos work. I actually have two questions: If I decided ...
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14 views

GPIO Tripping Relay Without Setting Output

I have a simple circuit set up with a GPIO pin connected to a relay and a LED connected to the other side of the relay. The light is off normally, when I do GPIO.setup(23, GPIO.OUT) in the code the ...
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1answer
23 views

PHP controlling my led control script. Can't get it to work

I have made a very small script for my raspberry pi where I turn on the LED. import RPi.GPIO as GPIO import time GPIO.setmode(GPIO.BCM) GPIO.setup(21,GPIO.OUT) GPIO.output(21,1) time.sleep(5) ...
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21 views

Control the inclinometer with RS232 or UART

I have bought an inclinometer today to try some things. Inclinometer has two communication port; RS232 and UART. Which one should I select? Actually I tried both but none of them worked. I have ...
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26 views

Controlling many stepper motors (not necessarily simulataneously)?

I would like to have an array of N stepper motors, and "step" a subset of this array once per second. Being completely simultaneous is not a requirement as long as any subset (from 1 to N, averaging ...
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1answer
31 views

Raspberry Pi and iMac display

A customer at my work has donated us a iMac G5 because it didn't do anything. We want to test if the display is still working, but I'm not sure if it will work. Does someone know if it is possible to ...
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2answers
58 views

PHP or jquery to execute python scripts for GPIO

I want to use php or jquery to control gpio pins on my raspberry pi 2. I have apache installed. When i execute python files using LXTerminal, they work fine. I have made the .py files executable and ...
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0answers
33 views

How do you use GPIO output with RPi and Google Coder?

I am trying to set up the "Blinky Lights" project with Google Coder v0.9. I have used the code from the example project, unaltered, as well as setting up my breadboard exactly as the instructions ...
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1answer
37 views

How do you decide between communication protocols? [on hold]

I'm experimenting with using the raspberry pi as well as an FPGA, and I want to try making some program that runs on the pi but uses the FPGA for processing. When looking at the pi output pins I ...
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3answers
261 views

Powering Pi from Ni-MH batteries

I would like to power my RPi2 from the 5V GPIO pin via 4 Ni-MH rechargeable batteries (4.8V) but I'm afraid about peak current. Can it somehow produce more than 2.5A? Should I use a fuse to limit that ...
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1answer
39 views

PI 2 - GPIO pin stays HIGH even when I toggle ( in Java)

Hi my first Java program to control a LED has failed, the LED does not come on even though the pin state is continuously HIGH ? Heres the Java code :- final GpioController gpio = ...
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1answer
27 views

GPIO's firing every ~3 milliseconds

I'm currently building a project using adafruits arcade buttons, and seem to be having a bit of an electrical problem. Using a Raspberry Pi 2 , and after confirming that wires aren't touching in ...
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1answer
14 views

Trying to shortcircuit a computer motherboard pin with the Raspberry Pi

So I'm working on a project which requires me to compile the kernel of my desktop machine at the office. But I do a lot of work at home using SSH. As the kernel is very delicate, it causes a lot of ...
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31 views

Connecting multiple devices with UART

So, I have the following components: Gertbot SparqEE Shield My aim is to connect these to a Raspberry Pi Model B+, so that they can work together. There are no issues when I connect these ...
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2answers
63 views

Read status of power led using sysfs

I want to read the status of GPIO35 on a Raspberry Pi 2 Model B using the sysfs on Raspbian with a 4.0.8-v7+ kernel. I can access other GPIO pins using /sys/class/gpio but the two leds are already ...
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2answers
71 views

How to connect a 24V input to my GPIO?

I have read on this website : http://www.ramge.de/powermonitor/doku.php?id=pulse_meter that I need a 200 Ohm resistor to connect a 24V input to the GPIO. I know that RasPi need a voltage between 2 ...
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2answers
40 views

Rotary encoder/monitoring multiple pins with Raspberry Sharp

I'm using Mono and the Raspberry Sharp library to try and decode the output of a rotary encoder. Raspberry sharp: https://github.com/raspberry-sharp/raspberry-sharp-io Rotary encoder data sheet: ...
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1answer
49 views

BCM 2835 library vs WiringPi library

What is the best library of these two? What are deference of these two libraries?
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1answer
22 views

TFT Buttons on SainSmart 3.2" LCD

Has anyone gotten the buttons to work on the SainSmart 3.2" TFT screens for Raspberry Pi? I have some ideas to make them call commands or Python scripts, but don't have any documentation from ...
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1answer
36 views

Strongly typed language for the Raspberry Pi? [closed]

I would like to know if there is a matrix somewhere that list the languages that could be used on a Raspberry Pi. I've a broad experience in C# and a not to bad knowledge of Java. For my first weeks ...
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5answers
60 views

need an opinion for portable power [closed]

I know opinion questions are frowned upon in the maker world (too many right answers and all) BUT I'm working on a pi powered security bot. I've got most of the prototyping and programming done (using ...
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1answer
18 views

AdaFruit PiPlate(LCD+Keys) + PWM port + DS18B20 temp sensor

I would like to know if it is possible to use at the same time, the Adafruit LCD+Keys + the PWM port(to control a MOSFET) + one temperature sensor (DS18B20) and its oneWire protocol? I was concerned ...
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1answer
81 views

Raspberry Pi 2, PIR project, all pins always get GPIO.HIGH value

I folowing this tutorial https://bhavyanshu.me/tutorials/raspberrypi-to-detect-movement-using-pir-motion-sensor-hc-sr501/11/21/2014/ and a little bit simplified my code. #!/usr/bin/env python # ...
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23 views

My Pi2 doesn't cognize One-Wire

I'm using Raspberry Pi 2 with Gentoo. I tried to use Digital Thermometer(DS18B20) with 1-wire so I prepared: login as: qwpo1030 Using keyboard-interactive authentication. Password: ...
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3answers
49 views

Is it possible to control a stepper-motor with javascript?

So I have seen some examples, how you can control servo-motors with javascript, but we use 2 stepper-motors for our project and these use an extra library in python. So is there a way to control them ...
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37 views

Light an LED in parallel with trigger switch

I have an old vintage camera that I gutted and put a raspberry pi into, similar to this project. I want to light an LED housed in the old flash housing when I hold down the button, as well as running ...
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0answers
22 views

Constant communication between raspberry pi and android device [closed]

I am a newbie to raspberry pi and I looking to define a webservice that will make the consistent communication between raspberry pi and android application. I am using its GPIO to control the ...
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1answer
42 views

Need 1 more 5v Pin - what to do?

First off I have only very basics of electronic understanding, so I welcome any help that I can get. I use a Touchscreen on my Pi that occupies all 5V and 3.3V pins. I also want to use a 433 ...
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2answers
125 views

How to read Analog 5V sensor ouput with Digital 3.3V GPIO?

I bought the "Sunfounder Sensor Kit" for Raspberry Pi 2, but the whole content is made for Arduino (5V). I have bought ADC, Level Shifters but I am stuck because I think I certainly miss a simple ...
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1answer
22 views

Access the display from a python app running as a service

Problem: The code below can't access the display when running as a service. I have my raspi hooked up to a touch screen monitor in the kitchen and I've attached a Passive Infrared sensor to the ...
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1answer
102 views

Is it safe to leave stuff connected to the GPIO pins when the Pi is powered off?

I am asking about stuff that would be within the normal operating limits when the Pi is on, i.e. 3v3 level voltages at small currents, when the pi is shut down (but still powered), and also when the ...
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1answer
45 views

using GPIO Reading from 4 inputs give me non accurate output

I am trying to read from 4 inputs to get an integer value but when I test my code the actual value does not match the expected My Code: import RPi.GPIO as GPIO import os, time i=0 ...
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2answers
83 views

Plug a 5V fan to GPIO 1 and 2

Regarding to the following picture, I understand that I can plug a 5V Fan by plugging it in between pins 1 and 2? This is right? (+ on 1 and - on 2?) My need : Plug a 5V fan to run all the time ...
0
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1answer
39 views

Connect usb camera to gpio pins

Is there a way to connect usb camera to gpio pins? The reason doing so is the inconvenient location of usb ports, hence my custom box for raspberry pi needs to be expanded just for usb connectors. I ...
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2answers
38 views

send gpio commands from rpi python script to another rpi

it is possible to control the Gpio of a raspberry pi connected by WiFi by another raspberry pi by a python script? I need to Connect\disconect some electric loads of my house switchboard, controled by ...
3
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1answer
110 views

Importing RPi.GPIO

I am just writing some code for a Raspberry Pi robotics project. Since I don't have a Pi set up as a workstation, I am using a Google Drive notepad to do write it in, which recognises Python syntax ...
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26 views

Controlling Stepper Motor Responding Strangely

I'm attempting to simply move a small stepper motor over GPIO using a Sparkfun Easy Driver. This Stepper motor is the one I'm attempting to use. I'm using similar code and configuration to that shown ...
4
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1answer
117 views

Hacking my alarm clock, how can I use it's built in display with my raspberry pi?

I'm looking into hacking my digital alarm clock to be able to control it with my Raspberry Pi A+. It has a typical 4 digit screen (7 segment) with two dots in between. The screen has a brand and ...
0
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1answer
49 views

wiringPiSetupSys - input pin state does not change

I try to port my GPIO project from quick2wire to WiringPi. My aim is to read the state of a photocell connected to pin 24 of my raspberry pi (model B, revision 2). My code (python 3) looks like this: ...
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95 views

Best way to use Raspberry Pi as a 5-drive NAS with RAID 5

What I've got: The 40-pin 528 MB B+ Raspberry Pi Five SATA hard disk drives 1) Is it best to use the four USB ports or find some kind of adapter for the 40-pin GPIO? 2) What do I need to ...
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1answer
30 views

Connect 2 different sensor to same ground

Can I connect 2 different sensors to same ground pin? Here's how I pictured it. Sensor1 and Sensor2 are ground of sensor 1 and 2.
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2answers
102 views

Why are some GPIO pins HIGH when the Raspbeery Pi boots up

I have an easy circuit wired up, with a 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 ...
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0answers
60 views

Specify interrupt in devicetree overlay

I have created a devicetree overlay to add an MRF24J40 transceiver to Raspberry Pi. The interface of the transceiver is SPI and an interrupt request. After some trouble the device finally appears in ...
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1answer
77 views

Not able to use Raspberry pi as a FM transmitter

I have refered to this video https://www.youtube.com/watch?v=6smyUoLugsg .The problem is, in it he has used a Raspberry pi (first model). I tried the things he told me but it wouldn't work. I urgently ...