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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466 views

Raspberry Pi 3 B+ is not turning on

I've bought Raspberry Pi 3 B+ yesterday and it was working fine for... an hour. After that I accidentally touched the GPIO pins with the heatsink (it wasn't glued so... I accidentally moved it to the ...
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2answers
1k views

GPIO event handler triggers off rising and falling edges

I'm trying to set up a tachometer. I used a comparator IC to get a real clean signal on pin 21 but I'm getting iterrupts on the rising AND falling edges. #!/usr/bin/python3 import time import ...
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299 views

How to display gpsd.utc using paint or similar method

I am receiving reliable gps data from my Adafruit gps sensor. I would like to to show the gpsd.utc data across the screen so that it appears like a regular clock. I have the following code which shows ...
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371 views

How wiegand reader only read the 24 bit?

H10301 is the HID standard wiegand 26 format where preprogrammed to have 2 parity bits, 8 bits facility code and 16 bits card number. My question is, how do wiegand device convert a 40 bit ID into ...
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48 views

RPi.GPIO “flush” interrupts

Intro It seems to me that when one adds and event detection, then removes it and the adds it again, something strange happen: 1) an event is removed to the "detection list"; 2) the event happens; 3) ...
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2answers
347 views

PIR Module False Positivesq

All I am working with a PIR Module and a camera for a project to provide text messaging when motion is detected as well as taking a picture. I am seeing a large number of false positives from the PIR. ...
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1answer
89 views

RPi Zero: Two UART devices at the same time

I need to read UART data from one device, and send different data to the other device, all via raspberry pi zero. It has only one UART TX and one UART RX on GPIO pins, but I heard that it is possible ...
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1answer
474 views

GPIO Newbie, can i connect this Crazepony FPV Camera to the Raspberry Pi?

I am a complete noob when it comes to RPi and GPIO I want to connect 2xthis Crazepony FPV Camera 1.2G 1000TVL 1/4 CMOS 2.8mm Lens FOV170 Degree NTSC Mini FPV Camera to the RPi over GPIO pins, but don'...
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1answer
447 views

How to check for alive process in an infinite loop and use LED as status indicator?

Clearly I'm a beginner when it comes to setting up a script. I'm trying to check if a process is alive and running, and if so, switch on an LED. I need help with the following: Check if a process is ...
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2answers
471 views

Is it possible to use more than one audio card on GPIO?

I want to use more than one HiFiBerry Dac+ on a single Raspberry PI. It's possbile? to connect more than one audio card?
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1answer
416 views

How to connect two cameras to one Raspberry Pi?

I want to use two pi cameras (V2) at the same time for a project. There are a few ideas that came into my mind Creating a camera MUX: 14 pins of the CSI port are connected to a bread board, and two ...
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2answers
54 views

Can I use Rpi 3.3V power pin (pin number 1, not GPIO signal pin) to power a 5mW green laser pointer originally powered by AAA x 2 = 3V bateries?

Let's say I have a device powered by 2 AAA batteries in series (1,5v x 2 = 3v and 625 mAh). Is it possible to replace the 2xAAA battery with the 3,3v Raspberry PI GPIO output? Or the 0,3v may be an ...
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124k 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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8answers
3k views

Libraries for interfacing with the GPIO

What libraries are available for interfacing with the GPIO?
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1answer
59 views

Nested Else issue. Very Basic

This is the code I am using to operate a relay to open my garage and the garage status is checked by a magnetic switch. However there is an issue with the logic can someone help me please as I am ...
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1answer
67 views

Reading Bytestream from GPIO / External Interrupt and CLK

So I have an external master device which bangs out a byte stream (DOUT), it indicates the upcoming stream on an DRDY. The timings are given from the master on an DCLK line. These three lines (DRDY, ...
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1answer
44 views

GPIO input output pins behaviour

As I am new to the Raspberry Pi my question may look simple to people My code is : import RPi.GPIO as GPIO GPIO.setmode(GPIO.BOARD) GPIO.setup(7, GPIO.OUT) print (GPIO.input(7)) while(True): ...
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30 views

GPIO pin turns off immediately when switch is connected, turns back on when disconnected

I have no problem turning on and off pins on my rpi4 (using both gpio on the terminal and Gpiozero with python3) however when I connect a wire (which is connected to a switch) to the pin... it turns ...
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1answer
2k views

What pins are actually being used by my 3.5 TFT?

I have a 3.5 TFT and I used these instructions to get it to work with RetroPie on my Pi Zero W. The reason this is important is although there are schematics for this LCD panel, I'm not using any of ...
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537 views

WittyPi board keep turning off Raspberry

I have a Raspberry connected with the WittyPi board. Been strugling to get it running without it dead locking. I have followed the steps in Witty Pi's manual http://www.uugear.com/doc/...
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1answer
20 views

Does a hat designed for RPi 2 B still work on Rpi4 (GPIO compatbility)?

I'm now continuing the design of a PCB (Pi Hat) that I started with a RPi 2 Model B. Will a RPi4 accept this hat? TL;DR: Does a RPi4 accept a Pi Hat designed for RPi 2 B? Or is there a break in ...
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622 views

Help with 3.5" display

i have a 3.5" display that works perfectly but i don't know how to connect it to GPIO. I'm searching on internet, but i am finding nothing. how can i make it work? I need to force video output to GPIO....
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652 views

GPIO pins on a RPI3 on Arch

I have a RPI3 with Arch on it and I cannot access any of the GPIO pins. When using a python wrapper like gpiozero to turn a pin on I get an error like: /usr/lib/python3.6/site-packages/gpiozero/...
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2answers
820 views

FreeBSD, GPIO, physical memory adresses

First my Assignment: I'm a beginner with BSD and low level peripherals like GPIO etc. and I need to toggle Raspberry GPIO Pins from a C programm on BSD. I am Using this BSD Image i took from here: ...
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Apply 3.3V onto an output GPIO pin?

My question in short: Will I damage my Raspberry Pi 4 if I apply (its own) 3,3V onto a GPIO pin that is set to output mode? (With current limiting resistor, of course) I ask this question because ...
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1answer
29 views

Why don’t GPIO lines work for DS18B20 Sensor?

Recently, I bought a DS18B20 temp sensor to monitor my fermentation temp of my beer and assumed I could just hook up the power, ground and data to their respective pins on the Pi but I could never get ...
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2answers
702 views

Interfacing with a 24V IO device

I have a UR10 industrial robot arm that I'd like to communicate with using it's IO board with my Pi 3B. I would like the arm to perform a pick and place routine after I detect that some operation is ...
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2answers
54 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 ...
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1answer
25 views

Signal from GPIO 14pin during raspberry pi booting

I'm doing an IoT project. I had a problem related to GPIO pin 14. Even though I solved the problem, now I have questions about pin 14. the question is below. During booting, relay connected to 14pin ...
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5answers
5k views

DS18B20 w1-gpio Device Tree gpiopin NOT = 4

I have a HAT which blocks GPIO4 so I cannot use the default pin for the temperature sensor, but I just cannot get it to work on another pin! I just get lots of 00- instead of 28- in /sys/bus/w1/...
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3answers
56 views

Voltage dropped significantly on GPIO 4 with a relay coil

I have a Raspberry PI 3 B+, and when I activate the GPIO 4 as output and checking agains a multimeter I get its 3.3V as expected. If I connect the GPIO4 to one end of a coil (http://www....
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1answer
726 views

Connect TFT Display with jumper instead of ribbon cable?

I wanted to rebuild this RPi Zero Project: https://learn.adafruit.com/pigrrl-zero/overview But instead of paying 50(!) Dollars for a 2.8 Inch TFT i wanted to get some other lcd... I do still need ...
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1answer
26 views

Is my ClusterHat faulty or my RPi GPIO fried?

I've been using a ClusterHat (1RPi + 4 PiZeroes) and all has been well until recently. The PiZeros boot off the RPi's SD card using the ClusterHAT-2018-10-09-lite-1-usbboot boot image, and when I ...
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1answer
55 views

Using Normal GPIO Pins as I2C (required)

We are attempting to use the Raspberry Pi as an embedded software platform. We are writing this in python, but currently we have it wired up to use 3 separate I2C busses. We have two of them wired to ...
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1answer
20 views

Addressing PCA9865 Servo Driver

Although not directly related to the Raspberry Pi, the piece of hardware I'm attempting to understand can be utilized by the Pi and it's a relatively basic concept that I'm looking for more ...
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1answer
3k views

Help reading audio data from I2S microphones

Using the Adafruit I2S MEMS microphone breakout board and the Raspberry Pi 2B, I am trying to read in stereo input using PyAudio and pass the data through a FFT to analyse. However I am not able to ...
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0answers
26 views

Oled Display doesn't work properly

Im using my Raspberry Pi zero W For an project with an Oled display and i can't get it to work properly I Installed Adafruit and tried the examples. It didn't work and i tried an other example but ...
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1answer
505 views

How do I connect two wires to one GPIO pin?

I plan to have a display (4-Wire SPI TFT LCD Display Module 240x320) connected to a Pi Zero: I know that to connect the display I need to wire the screen to the Pi like so: Display--------Raspberry ...
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2answers
32 views

do RPi3 3.3/5V pins output constant voltage even if the RPi power supply is changing voltage?

I want to power my RPi with a lithium ion battery. The RPi will be powering some devices which require constant voltage to power them. If I use a battery as supply for the RPi (which changes as it ...
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2answers
126 views

Different voltages across circuit when 3v3 to ground than when 3v3 to GPIO in

I have built a small Morse code key that consists of a push button, a 3v buzzer and an LED. When I connect the positive side to 3v3 and the negative side to ground, the key works. I push on the button,...
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2answers
399 views

Using Transistors and the GPIO, can someone please check my math?

I've done a couple of new schematics, this is my first time doing this, I was wondering if somebody could double check my math? Powering the RGB LED straight off the GPIO pins: Using the 5V rail and ...
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1answer
32 views

Run a code without being on the physical machine

I have some devices (i.e. leds) that I need to control on a Raspberry Pi, but I was thinking if there is a way in which I can put the code in a server, and then when the raspberry Pi receives a ...
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1answer
3k views

Reading HC-SR04 echo with wiringPiISR()

The following code works with the busy wait, but if I replace the while loop with a call to wiringPiISR() it always returns 0 for the distance. I also tried calling wiringPiISR() before raising the ...
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3answers
71 views

Controlling a led button and receiving input from that button

Ok, I have a button with a small 24v Led inside. My goal is to control the light depending on the state of the button. Quick press: toggle start/pause --> light on/off Long press (1500ms) --> reset -...
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1answer
589 views

Raspberry Pi - Press for on / Press for off switch

I've begun tinkering with using electronics and am also new to using Python. I was wondering if someone could help me please? What I'm trying to achieve is to use an on/off switch to run a motor - ...
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1answer
63 views

GPIO PWM. ESCs still run different after calibration

I’m putting a quadcopter together. I’m using a python script to calibrate the ESCs... they beep like a blinking led when I give them power. Then I run the calibrate script and they give me the proper ...
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1answer
112 views

How to hook up multiple devices with sda pins?

I am building something with raspberry pi. I am using the 16x32 led matrix as well as the port expander (MCP23017). Both use the SDA and SCL pins. I am having trouble hooking it up. I realize this may ...
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1answer
499 views

Use Adafruit Motor HAT and GPIO

How can I use the Adafruit Motor HAT and RPI GPIO at the same time? I just need an extra tall stacking header, or there is something I missing? My goal is use the Motor HAT and some LED and HC-SR04 ...
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1answer
160 views

Raspberry pi 3B+ won't boot, solid red light

My Pi won't boot, I was coding my Pi when my friend came and wanted to see a movie from the Pi, I shut it down normally and close the power supply, then changed the SD card that had kodi on and tried ...
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1answer
2k views

GPIO doesn't work, error: “Error when trying to open pin 11”

I connected a LED to pin 11 as per this guide. And this works in the terminal to turn it on and off: gpio mode 0 out gpio write 0 1 gpio write 0 0 But when I try to use pi-gpio, with this code as ...