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Questions tagged [raspberry-pi]

The Raspberry Pi is a credit-card sized computer that plugs into your TV and a keyboard. There have been several generations of the device with improved performance, more memory, and more connectivity. This tag should be used for electrical engineering questions that involve the use of a Raspberry Pi. For questions about the Raspberry Pi itself see the raspberrypi.stackexchange.com Raspberry Pi specific forum.

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32
votes
6answers
45k views

Embedded Programming for Beginners: Arduino or Raspberry Pi? [closed]

I'm a computer science student and I'm eager to expand my knowledge on embedded programming and electrical engineering. I've read here that using tools like the Arduino microcontroller is a good way ...
24
votes
3answers
2k views

What does “no fit” mean in electronics?

I have found at some places, especially: Raspberry Pi Forums eLinux RPi Hardware page the following wording: S2: DSI interface. 15-pin surface mounted flat flex connector (possibly no-fit) S5: ...
21
votes
1answer
17k views

Understanding an 'ideal' diode made from a p-channel MOSFET and PNP transistors

The Raspberry Pi B+ models have a protection circuit between the USB connector and the 5V net on the board. They recommend putting a similar protection circuity on a Pi HAT before 'backpowering' the ...
14
votes
4answers
22k views

Shutdown Controller for Raspberry Pi in a car

Following on from my previous question I'm trying to create a shutdown controller for my Raspberry Pi. The Raspberry Pi needs to be powered from the battery, but should power-down after the Pi ...
12
votes
5answers
8k views

Control the hardware of an old phone using a Raspberry PI

I have a very old phone (60 years old) and I want to control its part using a Raspberry PI: Microphone & speaker from the head set The bell The dial wheel I have the electric circuit but don't ...
12
votes
1answer
7k views

Plugging a LDR into GPIO pins of a Raspberry Pi

I want to connect a LDR into the GPIO pins of my Raspberry Pi, I know that Raspberry Pi doesn't have an analog-to-digital converter so what I want to do is to signal a HIGH signal (3.3v) on the GPIO ...
12
votes
2answers
7k views

Using a microcontroller to turn on LED strip

I have 60 leds that came in a led strip. One meter length of the led strip requires the following: 400 milliamps 12 volts I want to control these LEDs with micro controller. I'm thinking of using a ...
11
votes
4answers
10k views

shorting a remote control pushbutton with GPIO and a transistor

I'm trying to control my garage door remote with a GPIO pin from my Raspberry Pi. Instead of driving a relay, it would be much easier to just short the pushbutton on the remote. Is this how I should ...
11
votes
2answers
14k views

Using a 5v voltage regulator - Capacitors necessary? Better options?

I am very new to electronics. I am learning as I go, and I haven't quite found the answers I need; when it comes to programming, I'm not afraid of mistakes as they happen constantly. With electronics, ...
10
votes
1answer
1k views

I connect a 5 volts to a low resistance, but I measure a much lower current than I expect

I cannot understand why the current I expect is so different from what I am measuring. I found a very low resistor, 15 ohm and connect it to 5 volts. Why is the current I measure so low? Shouldn't it ...
9
votes
2answers
13k views

Is the Raspberry Pi a microcontroller or a motherboard? [closed]

I had quick question regarding Raspberry Pi: is it a microcontroller or a motherboard? It looks like a motherboard, but considering that it has its own dedicated memory and processor, it should be a ...
9
votes
5answers
12k views

Raspberry PI without OS on it?

I've been doing a lot with Arduino recently. It's very simple because you can directly execute C++ code on it without the need of operating systems or drivers. I've done some research and AFAIK, you ...
8
votes
4answers
3k views

Detect 220 VAC with a Raspberry Pi

I want to build a simple device to check if the light is on or off. I found some schematics but I need to be sure that it is safe. Source : How to detect 220 VAC voltage using an opto-isolator My ...
8
votes
8answers
11k views

Sending I2C reliabily over Cat5 cables

I am considering implmenting an home automation system around my Raspberry Pi but I found the price and space requirement of inserting a Pi every place some control is required too much but the Cat5e ...
8
votes
3answers
2k views

Breadboarding a Raspberry Pi

Ok, long time reader first time asker on this parcticulair stack-exchange. I am rather new to electronics, I've done some simple projects like Blinking Lights, alarms that go on when its dark and a ...
8
votes
3answers
4k views

Miniature Traffic Light with Raspberry Pi: Wiring many LEDs

Background: I am a Civil Engineer specialized in traffic control devices and I have a small hobby project to build a scale model traffic light system. I can manage and control the traffic light ...
8
votes
4answers
16k views

Circuit to safely power-down Raspberry Pi

I want to use a Raspberry 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 don't want to have to (tell my wife to) ...
7
votes
3answers
7k views

Raspberry Pi as JTAG programmer?

Other than obviously non-trivial problem of writing the software, is there any practical reason why the GPIO port of a Raspberry Pi couldn't be used as a JTAG programmer? I ask because I'm doing some ...
7
votes
2answers
7k views

Switching MOSFET from Raspberry Pi GPIO

I'm trying to drive a STP16FN06 from a Raspberry Pi GPIO pin but I'm a bit lost. The schema below represent (I think) how it is currently wired, on the left the RPi pin + ground and on the right a 5V ...
7
votes
4answers
1k views

Using a digital potentiometer in a voltage divider

I'm using an MCP3008 ADC and an MCP4131-103 (10k) digital potentiometer to try and create a sort of "adjustable voltage divider." For the project, the resistance I'm measuring will vary, and I hoped ...
7
votes
4answers
4k views

Wheatstone bridge sensitivity and accuracy

From my earlier question I was able to wire up 2 SEN-10245 weight sensors (each forming one half of a wheatstone bridge) with an AD620 InAmp & 47 Ohm resistor (to set the gain to ~1000). I then ...
6
votes
3answers
7k views

Using larger resistor values

I'm connecting a Raspberry Pi to an LED and this video tutorial says that I need 270 Ω resistors. I only have 100 Ω, 1 kΩ, and 10 kΩ resistors with me. Is it okay if I use the 1 kΩ resistor?
6
votes
3answers
675 views

Can I do this tutorial without a potentiometer?

I am trying out online tutorial to practice python and Raspberry Pi. I am currently following this tutorial. It says a potentiometer is needed, but I don't have one. The lcd I have is JHD162A What ...
6
votes
2answers
949 views

Voltage regulator misbehaves under certain conditions

Okay guys, this one has me baffled. Take these two circuits: Typical stuff; Power in goes to the + rail, GND to the - rail. This is a 19V power supply going in. It goes through the voltage regulator (...
6
votes
2answers
1k views

Microcontroller vs FPGA to DAC and ADC [closed]

I searched multiple forums about microcontrollers and FPGAs but I couldn't find the answer were I was looking for. I have to make a choice of whether I'm going to use a microcontroller/minipc like a ...
6
votes
5answers
7k views

Safety of using microcontrollers such as Arduino

I have been learning how to work with Arduino Uno R3, and it seems very intuitive and exciting for me. As many agree, I see lots of benefits of learning to use it at a young age. I would like to ...
6
votes
2answers
1k views

Understanding 74LVC245 datasheet and current source/sink

I'm using a SN74LVC245A (datasheet) to shift 5V TTL down to 3.3V so I can read the signals with a Raspberry Pi. However I am getting really weird results (a 60Hz input signal is picked up by the Pi ...
6
votes
5answers
5k views

Do you need to UL Certified the enclosure with the board inside?

I want to use the RaspberryPI in an industrial environment that requires all devices have UL certification. The RaspberryPI board has UL certification but there is currently no enclosures that are ...
6
votes
1answer
331 views

How does the Nintendo 64 detect a controller is connected?

To give some context, I am trying to emulate controller input to the N64 via a GPIO pin on the Raspberry PI. In an attempt to accomplish this, I have one of the PI's GPIO's in a pull-up configuration ...
6
votes
2answers
8k views

Raspberry Pi stereo camera frame synchronization/genlock (video or still image)

I need to frame synchronize a stereo camera for a computer vision application. The synchronization should the best possible, hopefully on a millisecond level. I would like to get about 10 FPS either ...
6
votes
2answers
8k views

transmit data wirelessly under water?

I am looking into constructing a small submarine with a Raspberry Pi. This is just for a hobby project but my idea is to have it communicate with the surface wirelessly. I know that normal radio waves ...
6
votes
1answer
2k views

How to fix RaspberryPi HDMI-DDC/CEC issue while keeping ESD protection?

The RaspberryPi (Type B, all revisions before B+) shows a more or less well-known issue with the CEC/DDC of connected HDMI devices. When powered down CEC between the connected TV set and other devices ...
6
votes
3answers
831 views

Determining Capacitor Discharge Rate

First time poster, apologize if I accidentally missed any rules. I've built a circuit that keeps a relay closed that is attached to battery power for a specific amount of time so my Raspberry Pi has ...
6
votes
0answers
507 views

Cheapest Raspberrypi (or MCU) power supply with both toggle *and* momentary switches? [closed]

TL;DR/main question: How would one modify this PCB to add an extra toggle switch that does not just abruptly cut the power to a load and that still allows enough time for a clean shutdown of, i.e, a ...
5
votes
5answers
19k views

Simplest uni-directional level shifter (3.3V -> 5V)

I want to drive a WS2801 LED strip from a Raspberry Pi GPIO. I have connected the MOSI and CLK pins directly to drive the LED but it is not working as the WS2801 datasheet says that a high level is \$...
5
votes
4answers
2k views

Powering a Fan with Raspberry Pi

I have a 12V computer fan that I want to hook up to my Raspberry Pi. It has a 7V sensor, 12V power and ground. I know that the Pi can only supply 5v so I’m just wondering how to hook it up to the Pi ...
5
votes
4answers
7k views

How do I reverse my electric motor?

For a pet project I am doing (trying to fly a kite using my computer) I need to move and reverse an electro motor to my liking (I took the motor from an old hand-held vacuum cleaner). I need to ...
5
votes
3answers
1k views

Can I screw up my board by guessing which RS232 pins are which?

I have a Raspberry Pi that I want to hook up to a serial (RS232) cable. I've found and read some information about this, so I know what pins on my RPi are Rx/Tx/3.3V/Gnd... Now the cable I'm hooking ...
5
votes
5answers
5k views

Looking to build signal level converter to reduce 20V input to 3.3v out. Am I on the right track?

I'm working on a small pet project with my RaspberryPi and I'm looking hook it up to some sensors. The output from the sensors is normally at 0v but when the sensor is triggered, goes high to 20v. ...
5
votes
4answers
7k views

Proper usage of a MOSFET to control USB

On the RaspberryPi.SE it was suggested that one can use MOSFET BS170 to switch a USB device on and off by a GPIO pin (3.3V). I need to get 500mA to power a GSM dongle; the voltage drop should ...
5
votes
3answers
742 views

Multiple switches, same function. Can they be wired in parallel to a single I/O pin?

I'm working on a Raspberry Pi project that requires 30 separate momentary switches to be hooked up to trigger the same function within the software. It's for an art project. I don't need to ...
5
votes
2answers
1k views

Raspberry Pi as basis for commercial device?

I am thinking of using a Raspberry Pi as the basis of an electronics project that I am working on, and plan to eventually sell to the public. I want to use the Raspberry Pi in order to reduce the ...
5
votes
1answer
139 views

Raspberry Pi Zero HDMI socket - available current?

I have an ongoing question on the Raspberry Pi SE site, in which I'm attempting to figure out how much current is available to devices connected to the HDMI socket of each Pi model. I think I've ...
5
votes
2answers
459 views

Use ATX power source to power Raspberry Pi

I'm setting up several Raspberry Pi's and Arduinos connected together, and I'm looking for a way to power them. Would it be possible to adapt an ATX stock power source with female USB plugs using the ...
5
votes
2answers
2k views

Using the raspberry pi to measure multiple electrical circuits

I am looking to use the raspberry pi to measure the power consumption of multiple household electronics and record the information to analyze later on. However, I'm not sure if it's possible to ...
5
votes
2answers
1k views

Cannot get a digital square wave on oscilloscope from the GPIO of the Raspberry Pi?

ENVIRONMENT: Running "Raspbian" on Model_B Raspberry Pi (Revision 2) w/ ribbon expanding the GPIO out onto a Breadboard as shown in the following image. SETUP Here is a close up of the GPIO setup ...
5
votes
3answers
2k views

Serial bus Raspberry Pi to multiple AVRs

Background: I'm trying to replace the electronics for a ice hockey scoreboard. The old electronics had the following issues: It stop working. I have since discovered that a couple of diodes and ...
5
votes
3answers
915 views

What should I use for powering a Raspberry Pi at near space altitudes?

I'm planning a high-altitude weather balloon project (to around 100000 feet) some time down the line to take video and pictures of near space altitudes and I have some questions I need to ask before ...
5
votes
2answers
2k views

Tradeoffs of XBee vs. Wifi for remote sensor & camera

I'm planning to build a remote sensor for my driveway gate, which is about 250' from the house (line of site). The basic requirement is to notify my HA system when the gate opens or closes, but I ...
5
votes
1answer
700 views

Low-side MOSFET: Current seems limited

I'm trying to use a MOSFET, an N-channel (specifically IRLB8721PbF), with a gate controlled by an AVR to power on/off a Raspberry Pi (powered through GPIO), I'm using it on the low side. (Both share ...