Questions tagged [electronics]

Use this tag for questions related to how to use control electronics from the Raspberry Pi, and how to control the Raspberry Pi from electronics.

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5
votes
1answer
4k views

Do I need a current limiting resistor in series with a magnetic door sensor?

I'm building an alarm system and I'm using a magnetic door sensor, conected to ground and a pin of the gpio set up with an internal pull-up resistor. As far as I know, this means that the pin will be ...
29
votes
5answers
28k views

Circuit to safely power-down Pi

I want to use my Pi as an XBMC server in the car. The XBMC docs say that you should always use the shutdown command before disconnecting the power. I've been thinking that it should be possible to ...
32
votes
4answers
17k views

Using Raspberry Pi without a Linux OS?

I'm interested in using the Raspberry Pi as a pure embedded CPU unit, for the development of embedded applications. Since the Raspberry Pi has a powerful CPU with quite a bit of memory, it makes an ...
8
votes
3answers
8k views

Powering a 3-12V water pump on raspberry pi

I've got a 3-12V water pump, a raspberry pi, a relay (5V 10A/120VAC, and a breadboard power supply supply 3V-5V. The questions are : Is it possible, to rspi to breadboard power supply usb, and a ...
8
votes
5answers
11k views

How can I turn an GPIO to its alternate function?

I want to use the altenate function of GPIO 4 namely the GPCLK0 function. How can one set a GPIO to its alternate function? Many alternate functions are summarized here: elinux-wiki The best would ...
6
votes
3answers
10k views

How fast is GPIO+DMA? Multi I2S input

I want to connect multiple I2S ADCs to RaspberryPi and record multi-channel audio. I calculated that it requires copying GPIO input port to RAM at 3072kHz (or every 0.33µs). I want to do it using DMA. ...
4
votes
3answers
4k views

I am getting ghosting/bouncing on my digital input

I am meassuring data pulses from my electrical meter, giving me one pulse per Watt used. I have 4 electrical meters connected to my Raspberry Pi model B. I have connected them directly like this (no ...
0
votes
1answer
4k views

Controlling a brushed motor ESC from the Raspberry Pi

I've tried solutions from similar problems, but none of them gave me any usable results. I'm trying to control those http://www.ebay.com/itm/311177661450 electronic speed controls (ESCs) with ...
0
votes
2answers
85 views

How to know if Raspberry is running

I'd like to implement an electronic circuit to be able to restart my raspberry Pi when it has been shutdown (without plugging in and out the USB charger, which will obviously remain plugged all the ...
10
votes
5answers
5k views

What is an easy way to electromagnetically shield a Pi?

My friend and I are working on a Civil War telegraph project, and we incorporated a Pi into the project, for reading and displaying the received code from the key. My friend created a period correct ...
5
votes
3answers
4k views

Calculating resistor value for transistor

I'm creating a circuit with an infrared led and a transistor connected to a gpio pin. I'm currently using 5v with a 40 ohm resistor (four 10 ohm resistors chained) but I'm not sure what resistor to ...
4
votes
4answers
4k views

Logic converter for relay module or extra resistors and transistors?

I would like to use a 8 channel relay of SainSmart for house automation: http://www.sainsmart.com/8-channel-dc-5v-relay-module-for-arduino-pic-arm-dsp-avr-msp430-ttl-logic.html This Relay module ...
0
votes
1answer
542 views

Long length of wire off of GPIO pins

I am building a circuit with the Raspberry Pi that requires a button about fifty feet away from the central circuit. I am planning on using speaker wire for the connection from the Pi to the button. ...
11
votes
6answers
14k views

GPIO: Why wire button to ground rather than +3.3v?

In most examples I've seen of wiring buttons to GPIO inputs, the button is wired so that when closed, a circuit is completed between the pin and ground, producing a low input on the pin. A pull-up ...
4
votes
1answer
6k views

Connecting a standard telephone through GPIO

I am wondering if you can interface a standard, RJ11 telephone through GPIO, and input an output through the phone, even using asterisk to connect to voip. The phone I have is a GE model number ...
0
votes
1answer
226 views

Do I need a resistor for a 3v3 led? [duplicate]

Begginer question, if the output voltage of the raspberry pi is 3.3v and my led voltage is 3.3v, do I still need a resistor? As far as I understand, if the voltage is the same you don't need to add a ...
5
votes
2answers
3k views

Electrical characteristics of GPIO

Is there a spec sheet anywhere which lists the electrical specifications for the varios GPIO pins on the RPi revision B? For example, if they are open collector etc, output voltage, max input voltage, ...
3
votes
1answer
235 views

5.8V Electrical Short = half baked Pi (or, questions about damaged but still working Pi)

I just shorted 5.8V+ (4 half-done AA batteries) through my Pi... at most for 3 seconds... it went through somewhere near the ethernet port... whilst connected to the ground of the circuit, also ...
3
votes
2answers
658 views

Using an L293D chip (to control a motor) with a separate power supply

I've got an L293D Motor Driver chip powered by 4.5v via some batteries and am trying to send high signals via the GPIO library in Python to control a motor, however this does not seem to work. My code ...
2
votes
1answer
8k views

Raspberry PI as intercom?

I am currently looking for a way to connect an intercom to the raspberry pi, at the moment, the intercom wires are connected to a regular telefphone ( only two wires needed ), when someone dials the ...
1
vote
1answer
38 views

Is a RC snubber required when using the pi with a relay?

I am hoping to use raspberry pi to switch on and off a heating lamp and an aquarium pump via a relay switch. Both devices are plugged into 120V AC normally. The relay tutorials online seem to be ...
1
vote
1answer
272 views

Environmental Tolerance

I am planning a use for the RPi where it will be permanently connected to a car via the CAN-BUS. While other questions have discussed the stability of power, I am more concerned about the environment....
1
vote
2answers
2k views

3V3 enough for a 5V relay?

I currently have this relay, and it is a 5V relay (for the control circuit). Seeing as how our GPIO pins are rated at 3V3, I connected constant 3V3 power to Vcc and a GPIO pin to In1 to actually ...
1
vote
2answers
81 views

RPi 1 Model A input/output pin ratings

RPi 1 Model A here. Brand new to RPi and electronics in general. I'm finding a hard time finding the exact voltage/current "ratings" for my model but the closest I could find was a comment under this ...
1
vote
1answer
118 views

same GPIO input signal on multiple raspberri's from one source

Im having 7 raspberri pi's 3 connected to 7 screens, running an python 2.7 app to download different images from google drive, every raspberry has different images. Geeqie is displaying those images ...
1
vote
2answers
841 views

Limiting GPIO input voltage

I am a very recent new Pi owner and am setting up to build a 'lab board', with a breakout breadboard for the GPIO pins. I have read a great many dire warnings about frying the Pi if I accidentally ...
0
votes
0answers
208 views

How to connect sensor to Raspi via poor man’s a/d converter?

TL/DR: I’m using this and there are things I don’t understand about this circuit. Ultimately I’d like to read data from this sensor, but all I get is gibberish. Please, help. I have set up “poor man’...
0
votes
3answers
311 views

Powering an element that draws more current/voltage than GPIO can supply?

I'm a little over my head here and I'm hoping someone might be able to help. I'm trying to control this Heating Pad using Raspberry Pi GPIO pins, turning it on and off via GPIO. It takes 5V DC and ...
-2
votes
1answer
83 views

How to get started with basic Raspberry Pi electronics?

I have received a RPi 3 kit as a gift with tons of sensors, cables, resistors, etc. I have managed to get the typical LED demo working by following literal instructions but I don't understand how to ...