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18 votes

USB card as my default Audio Device

With Raspbian Jessie and newer (Stretch, Buster, Bullseye), changing the default audio device is simpler than it used to be. Now, simply use this command to list your alsa-detected sound cards, and ...
semitones's user avatar
  • 431
8 votes

Raspberry Pi 3 audio input?

That is correct, there is no audio input. The Pis generate analogue audio output using simple pulse width modulation (PWM) which is an efficient way to make output audio, but in the case of the Pi, it ...
Matt's user avatar
  • 966
4 votes
Accepted

Generating alternating current from GPIO – is it a misuse?

While the suggested schematics may (or may not) work it is indeed a lot of effort to save the ground wire (just as joan's answers points out). Don't think of GND as a third pin. It's not a GPIO pin, ...
Ghanima's user avatar
  • 15.9k
4 votes
Accepted

GPIO Voltage tolerance for input

There are no formal published data, but the following summarises what I have been able to discover. Electrical Specifications of GPIO I would NOT apply 3.6V to a GPIO pin, but if the voltage does not ...
Milliways's user avatar
  • 60.3k
4 votes
Accepted

UART RX stops reading data after working correctly

Check if you have disabled the login prompt on /dev/serial0. What you see may be due to two processes (your script and getty) reading from the same port. Login prompt on serial port can be disabled ...
Dmitry Grigoryev's user avatar
4 votes
Accepted

Why is pull up resistor preferred over pull down for the matrix keypad?

In general the reason electronic engineers prefer pull-ups to pull-downs is that in silicon N type (NPN bipolar or N-channel FET) transistors are better than P type transistors (PNP bipolar or P ...
Peter Green's user avatar
  • 6,486
3 votes
Accepted

Wireless USB Touchpad not working as mouse. Why?

I found the answer to this problem in the following topic: https://unix.stackexchange.com/questions/231139/libinput-touchpad-is-dead-around-the-perimter Summary: Create a new file /etc/modprobe.d/...
Omid1989's user avatar
  • 662
2 votes

Raspberry Pi 3 audio input?

You can use one of those USB sound cards, or if you don't want to hog up USB ports but don't mind using the GPIO pins, you can use the Cirrus Logic Sound Card (audiophile-grade hardware though, fairly ...
Maxthon Chan's user avatar
  • 1,051
2 votes

Generating alternating current from GPIO – is it a misuse?

Seems to be a lot of effort to save a ground wire. The GPIO may be toggled millions of times a second. Thinking about it the lines will be floating so you'll need to enable the internal pull-downs ...
joan's user avatar
  • 71.1k
2 votes
Accepted

Using a remote control without Lirc

Since your remote already sends normal keyboard commands, I'd recommend something simple that maps keypresses to play sound files. The following simple Python script will do that. It uses termios to ...
Anon Coward's user avatar
2 votes
Accepted

GPIO input voltage from sensors - need clarification

The Pi's GPIO are all 3V3. There appears to be limited protection for higher voltages such as 5V but the advice will always be use a level converter (such as a voltage divider) if you can. If you ...
joan's user avatar
  • 71.1k
2 votes
Accepted

Can the rpi get audio input through usb?

USB audio is standardized and for the most part those little adapters with the familiar "green stereo in, pink mic out" 3.5mm jacks that you can buy online or in stores for $10 will work (if you are ...
goldilocks's user avatar
  • 59.1k
2 votes

Set up C-media USB soundcard for microphone input on Raspberry Pi 2 with Raspbian Jessie

I've finally solved this issue on my side. I hope this ends up being the problem you had too... The problem was the microphone plug. I was unaware there are two kinds out there: 3-pole, and 4-pole. ...
R Porter's user avatar
  • 121
2 votes

Wireless USB Touchpad not working as mouse. Why?

I am not sure this counts as a specific answer but as you are using a Logitech "Unifying" receiver you may like to get the Solaar utility from its Github site or an older version from the solaar ...
SlySven's user avatar
  • 3,621
2 votes

How can I determine if a given touchscreen is compatible?

Well, I had the same problem and had to find out that this question is a rather hard one. This blog entry introducing the official 7" RPi display explains some of the most important keywords involved ...
Fantilein1990's user avatar
2 votes
Accepted

PyAudio does not detect my microphone connected via USB audio adapter

I'm updating this answer to include the discussion from the comments and flow more like a troubleshooting guide for future readers. Make sure your USB device is compatible with your microphone. Some ...
Jon Musselwhite's user avatar
2 votes
Accepted

3.5" TFT Calibration Problem

Shuffling config files around (e.g. renaming /usr/share/X11/xorg.conf.d/10-evdev.conf to /usr/share/X11/xorg.conf.d/45-evdev.conf) will only matter if these files have conflicting duplicate options, ...
Dmitry Grigoryev's user avatar
2 votes

aplay/arecord device order changes every reboot

For anybody interested in the solution to this problem when two devices have the same snd_ identifier: In alsa-base.conf, use the vid and pid attributes on options (they both accept comma-delimited ...
Chris Manning's user avatar
2 votes

Error when connecting more than ten USB devices on Raspberry Pi 4

The theoretical limit for USB is 127 devices. But, that is not really true. First of all, the limit of 127 may not be 127, but 96. Yes it looks like a USB 1.1 hub in your log and the 96 limit is for ...
Ljm Dullaart's user avatar
  • 2,521
2 votes

How to overwrite the inputs in Retropie for specific emulator/rom?

You should be able to start the game and then bring up RetroArch's RGUI menu using Select+X On that menu use D-pad Up and Down buttons to highlight Controls and press A to open that. Then select ...
RedGrittyBrick's user avatar
2 votes
Accepted

How can I use a GPIO input pin for a 12v circuit?

When the button is pressed the red side of the button will be at 0V. But when the button is released it will go to 12V and fry your RPi. Also 0V for the power plug can differ from 0V for the RPi. If ...
Goswin von Brederlow's user avatar
2 votes

Most compatible/supported I2C based touchscreen to emulate?

There are many touschscreens for the Pi that use an I2C interface. Pimoroni's HyperPixel uses a FocalTech FT6236. Datasheet for the controller. AdaFruit's PiTFT 2.8" uses a FocalTech FT6206. Both ...
Phil Robinson's user avatar
2 votes

Simulating a Keypad with Raspberry PI

I'm pretty sure your lock doesn't react to a voltage level, otherwise it would be useless: connecting it to a charging capacitor will sweep through all possible voltage levels and inevitably open your ...
Dmitry Grigoryev's user avatar
2 votes
Accepted

Simulating a Keypad with Raspberry PI

The keypad looks like it uses a voltage divider to generate a voltage signal. One resistor stays constant while the other resistor is connected when its corresponding button gets pushed. Depending ...
Abel's user avatar
  • 287
1 vote

Camera not in /dev/ how to create one

The command you are looking for is mknod However, the creation of special device files is not for the faint of heart. Make sure you know exactly what you are doing. For further reading: mknod ...
RubberStamp's user avatar
  • 1,399
1 vote
Accepted

Are there any buzzers that work natively with 1 Model As?

Strange that you have such a hard time finding one, I did use a search engine with "piezo 15mA" and the first two hits where 15mA/1.5volt piezo buzzers. And a caution, your circuit can break your ...
MatsK's user avatar
  • 2,811
1 vote

Use USB microphone as input, but keep internal sound card as output

Since December 2020, Pulse is added to stock Raspberry Pi OS, so you could just upgrade your system and select default input and output devices (called sink and source respectively) in PulseAudio ...
Dmitry Grigoryev's user avatar
1 vote

Connecting digital output device directly to pi's gpio

Per joan's comment below the answer, you can't use 5V logic with a Raspberry Pi's GPIO pins. They're only 3.3V tolerant and have no over-voltage protection, so if you exceed 3.3V you're quite possibly ...
goobering's user avatar
  • 10.7k
1 vote

Raspberry PI 3 reading input value with push button

If the other side of the switch is connected to ground, then a "pull_down" function would automatically give you a false result because the pull down resistor is also connecting to ground, effectively ...
GCass's user avatar
  • 31
1 vote
Accepted

What do I need exactly

Try the Foundation guides https://www.raspberrypi.org/help/ the Hardware Guide deals specifically with needed hardware.
Milliways's user avatar
  • 60.3k

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