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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Smartphone instead of Raspberry Pi… is it possible? [on hold]

I have been wondering whether it is possible to use cheap china smartphone, supplied with some peripherials for GPIO, instead of Raspberry Pi. I found this question after some googling, but no ...
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5 views

GPIO Threaded callback synconization [on hold]

I'm trying to make a simple python script that waits for a motion event and will turn on the monitor when it detects a rising edge. Once a motion event is triggered I want the script to wait 30 ...
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2answers
17 views

Securing GPIO groups vs gpio-admin

The project I am working on right now requires a webserver and some server side code to access the gpio pins. I know that the pins require root access and I need to secure them before I open it up to ...
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1answer
36 views

Momentary switch as GPIO input - Trouble with code and bouncing/floating

Update So this is now the code I'm running. It now works but is bouncing/floating. - I believe this can be controlled within the code itself by looking for an edge value as opposed to a high or low, ...
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1answer
22 views

Available GPIO Pins for Transmitter

I have a touchscreen that uses the following GPIO pins on my B+: PIN NO. SYMBOL DESCRIPTION 1, 17 3.3V Power positive (3.3V power input) 2, 4 5V Power positive (5V power input) 3, 5, 7, ...
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42 views

Raspberry Pi multiple NFC readers

I am building a Raspberry Pi B+ powered survey device. It would use NFC scanners for multiple choice questions. It should display a question on LCD screen and the user should have his NFC tag scanned ...
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28 views

Alarm System - Detect 2.5V or 5V

I'm a newbee in raspberry and would like to add a raspberry on my home system alarm. I have 4 zones, and checked the voltage on the four cables: 2.5V when nothing is detected and 5V when motion is ...
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1answer
37 views

How to run 2 servos with wiringpi2 on Raspberry pi 2

Hello I want to use 2 servo with different gpio pins. But Raspberry has one hardware pwm (GPIO 18). first of all I tried another pin to run servo and my code: wiringpi.pinMode(18,2) ...
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5answers
84 views

GPIO Pin Explanation

My Pi 2 kit came with the following GPIO pin reference card. In addition to showing all of the 5V, 3.3V, GND, and GPIO pin numbers, it has additional information on some of the GPIO pins like TXD, ...
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19 views

kernel Disabling IRQ #49

I am using the RPi_GPIO library in a python shell to read a raw wireless signal using the wait_for_edge() function in a loop like so: while True: GPIO.wait_for_edge(26, GPIO.RISING) print 'R' ...
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4 views

Can an RPi2 core be dedicated to one user-space app? [migrated]

Can an RPi2 core be dedicated to one user-space app, for the purpose of bit-banging GPIO without any interruptions?
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7 views

Java Audiostream stops after X times

im working on a raspberry pi project. it runs java code, wich opens a wav file and plays it. when i press the button quickly a few times it doenst play the sound anymore. UPDATE: the ...
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1answer
35 views

GPIO protection diodes, maximum input current

I'd like to use the Pi to measure AC frequency, and to keep the circuit as simple as possible, I wonder how much abuse the GPIO pins will handle. PIC and AVR microcontrollers have protection on all ...
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3answers
45 views

GPIO Signals Over Long Wires

I did some searching and found a few topics related to this, but most seemed pretty old and I didn't get a clear answer. My hardware/circuits knowledge is pretty basic, so please bare with me. I have ...
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1answer
87 views

Using PWM in a Windows 10 App with the Raspberry Pi 2

I am a newbie an I have succesfully use a RBG Led, and I emulated PWM by code but it is too slow (and in somehow the timer autostops), Then I watched that the standard libraries support GPIO.PWM but ...
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0answers
31 views

Keep state of GPIO pin

I've been following a guide for implementing GPIO pin control via a web interface running on my PI. The guide uses quick2wire-gpio-admin for controlling the GPIO pins and for serving the web page (my ...
2
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1answer
41 views

Help understanding + hacking spi-bcm2708.c

I'm an embedded software engineer who is not familiar with the linux driver model, but familiar with device drivers in general. I want to do something simple, namely, wiggling a couple GPIOs from ...
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3answers
116 views

Cannot open 12V Solenoid Valve

I am a beginner in DIY electronics, and I am attempting to control a 12V Solenoid valve from a Pi B2 connected to a 12V Battery and WiringPi Pin 1. I am using a 1kOhm Resistor between the gpio pin ...
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2answers
55 views

How to disable a GPIO pin?

Basically, I want to disable or off a GPIO pin whenever I execute a method in python. Anyone knows how to disable the pins?
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0answers
33 views

Led - Manual control of WS2801 chip

I'm wondering if there's a way to manually control a multicolour LED strip powered by a WS2801 chip, i.e. being able to type a bash command from raspbian or any kind of software control, something of ...
2
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1answer
108 views

Use an Android tablet display with Raspberry Pi

I want to use my old android tab (dead) display with Raspberry Pi. I am thinking of connecting screen via I/O ports of Raspberry Pi. I need to find display driver for tabs screen, as my Tab is dead, ...
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1answer
40 views

Raspi Type B with MQ sensors (updated)

Is there any other way to integrate raspberry pi with mq sensors?? I've been successful with one mcp3002 and one mq-2 sensor but is it possible to add another mq sensor (mq4,mq6) and should i provide ...
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1answer
48 views

ESC control by RPi B to manage brushless motors via python

This post may be similar to other ones, but they didn't solve my problem: I've gor four Hobbywing Skywalker 40Amp ESCs, to control four brushless motors (these ones) to make a quadcopter. I plugged a ...
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35 views

Raspberry Multiwii [closed]

I'm want build an quadcopter drone with a raspberry pi. So, the raspberry should send a control (throttle, pitch, roll ..) to flight control (Multiwii AIO Flight Controller w/FTDI) and that the fc ...
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0answers
22 views

Return from a gpio event

Finally I was able to fix this with a program that uses gpio.add_event_detect, but when I get the audio file I need to send it to another function and get text that that function return. This is my ...
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1answer
27 views

How to program an interrupt that is not dependent on GPIO? [closed]

You can program an interrupt so that the Pi can wait for something like a rising edge on one of its GPIO ports. But, can you program an interrupt for an event that is not GPIO dependent? For ...
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1answer
54 views

Raspberry Pi as slave

I am using a Pi compute module and wish to make two of them to communicate to each other. I have hooked up some slave I2C devices to it (RTC, Temperature sensor). So I don't think making Pi as slave ...
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1answer
77 views

Raspberry PI 2 Model B Not Detecting ds18b20 Sensor (Tested with Multiple Sensors)

I just wanted to ask some advices. I have tried everything I could find, including : /boot/config.txt add Line dtoverlay=w1-gpio,gpiopin=4 Update and Upgrade Updating firmware Buying new Sensors. ...
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0answers
52 views

WiringPi and CGI in Python

I want to be able to toggle a GPIO pin from from a web browser. I've found this forum topic (http://tiny.cc/d1eixx) and even the though code seems fine, it doesn't toggle the pin: #!/usr/bin/python ...
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1answer
147 views

A way to solder composite video directly to RPi B+ board?

I have a b+ newly purchased that I'm slimming down for a handheld build. Ideally, I'd like to be able to solder my composite video connection to the underside of the board like I could with a model ...
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1answer
53 views

Power over USB vs from Raspbery

If I connect a relay to Raspberry PI (Ground to Ground, VCC to 5v, and switch pin to one GPIO), when I write 1 on that pin, the relay switches on and off. But, if I connect the relay Ground and VCC ...
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1answer
53 views

Screaming Jelly Baby program problems

I am quite new to using the Raspberry Pi2. Currently I am trying to run the Screaming Jelly Baby program in Python by using the GPIO pins ...
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1answer
35 views

Modifying GPIO memory for one pin turns multiple on

I am attempting to write an API for interaction with the GPIO pins in a bare metal environment in C. However , sometimes when I attempt to turn on one of the GPIO pins it turns multiple on. Here is ...
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1answer
84 views

GPIO Voltage Thresholds

It is obvious, that 3,3 V is a HIGH, and 0 V is a LOW at a GPIO input pin. But I am looking for the exact voltage thresholds for the GPIO input pins. I have a Pi B+ and a Pi 2. Watching this video ...
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18 views

How “security” is addressed when connecting pi with wireless transmitter and wireless switch

(I'm new here please forgive me if asking this question is not in line with the etiquette) Michael described how to control 433MHz receiver with Pi However, these Elro receivers require the pairing ...
3
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1answer
65 views

RGB LED is not lighting up

I connected an RGB LED(common anode) via the GPIO, and tried to get it to light up, but for some reason when I run the command, the LED does not light up. Here's the code I'm using import RPi.GPIO ...
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44 views

How can I trigger a bash script to run when a GPIO button is pressed?

I am doing a project with my raspberry pi where it will take a picture out a peep hole in my door and email me when the door bell is pressed, how can I set this up?
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30 views

Determining correct J3 jumper setting on Compute Module IO Board

The Raspberry Pi Compute Module Development Kit Quick Start Guide says that prior to using the kit, the IO bank voltage jumpers (which power the GPIO banks) should be checked. However, I can find no ...
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1answer
36 views

How to make a remote pigpiod socket call?

The pigpio GPIO library seems to provide a mechanism to invoke the pigpiod demon remotely using TCP/IP sockets. However, there appears to be some details missing. For example: Do we use a TCP or ...
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1answer
27 views

The Current in mA at 3.3 V When Using the Internal Pull-up Resistors

I'm using RPi.GPIO in Python 3. If I do GPIO.setup(24, GPIO.OUT, pull_up_down=GPIO.PUD_DOWN) GPIO.output(24, 1) will then a current flow internally from the pin to ground even if it is not ...
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1answer
94 views

Understanding the library from MCP3002 ADC chip

can somebody explain to me about this mcp3002 library used in analog to digital conversion?? It has some connection to my first question here. # botbook_mcp3002.py - read analog values from mcp3002 # ...
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42 views

Gpio state can't be changed when connected to a DC motor or led

I am using the pi4j library to control the gpios on the raspberry pi B, but I ran in the following problem: when I start a pi4j example like ControlGpioExample.java then the led(with resistor 220 ohm) ...
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2answers
142 views

Can we determine the mode of a GPIO pin?

As I understand it, the mode of a GPIO pin can be INPUT or OUTPUT (and I think there may be other modes such as PWM and I2C). I believe that the mode of a pin is a global and that if two applications ...
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1answer
100 views

How to Connect 9 Volt RS232 to Raspberry Pi GPIO

I am trying to connect RS232 Port to Raspberry Pi using PL2303 USB To RS232 Converter and PL2303 USB To RS232 TTL Converter These Both connect at /dev/ttyUSB0 I try minicom command to read ...
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1answer
164 views

how to connect RS485 Port to Raspberry Pi?

I have a battery controller which give Voltage of battery via RS485 Half Duplex Transmission using RJ45 port. we can connect this device to windows pc using these cable/convertors. When we ...
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1answer
30 views

gpio export works, but gpio write wont

It seems that I am missing something or I have mis-configured something. I have a garage door opener connected to a relay to my GPIO. If I use gpio export 17 out the circuit will complete and the ...
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26 views

Troubleshooting MCP23017 based display

I am having trouble getting characters to display on my Adafruit 16x2 blue/white monochrome LCD + keypad. I am wondering how best to isolate the problem as either hardware or software. It shows up in ...
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1answer
244 views

Problems Regarding Raspberry Pi Project with MQ-2 Gas Sensor

Recently I have been learning Python implementations on Raspberry Pi's GPIO system. I'm interested in wireless sensor network examples and decided to make a fire alarm system using MQ-2 sensor as the ...
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2answers
52 views

How to have a Raspi trigger a Remote Control physically

I have a Remote Control for my windows shades and I would like to be able to trigger them using some software using a web interface or an android app. As I am an enthusiast programmer I would like to ...
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1answer
64 views

ruby on rails in RPI

I want to control my RPI from my phone, so I decided that the RPI will host a site. I'm familiar with ROR and I saw that there is GPIO gem (pi piper). Should I work with ROR or learn Django and use ...