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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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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 ...
0
votes
1answer
2k views

multi channel ac dimmer for arduino

I have been looking for a simple ac dimmer circuit to use with my arduino and/or raspberry pi. I have used the TLC 5940 PWM Driver before just to control LEDs and I wanted to adapt this to controlling ...
4
votes
4answers
17k views

Control 5v relay through 3.3v GPIO using NPN transistor

I'm not very pratical as I just started learning electronics and I'm planning to make some experiment with Raspberry Pi. I'm trying to control a 5v relay board that, I think, is made for Arduino, as ...
3
votes
1answer
2k views

How can i drive a 5v 120VAC 80mA with 15A contacts with a raspberry pi?

I don't have a very good knowledge of electrical engineering yet but I'm working on it. I will like to know as simple as possible, how can i drive a latching relay that needs about 70-90mA if the ...
1
vote
2answers
4k views

How to force variable voltage fast charging power bank to output a certain voltage?

I am trying to power up my raspberry pi 3 with a Xiaomi 10000mAh fast charging power bank through the L298N motor controller. The motor controller can receive from 7 to 35V, and it has a 5v output, ...
11
votes
4answers
11k 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 ...
7
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 ...
0
votes
1answer
5k views

Raspberry PI's SPI over RS485

I'm trying to understand how to connect a SPI device (a mifare RC522 RFID board) over long distance to my RPi via SPI. I searched and find I could connect those via SPI over RS485 using a MAX490. (...
2
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4answers
21k views

Embedded system for image processing project

Is it possible to do image processing (to extract numbers and text) using a microcontroller? If not, what are the alternatives to do this task?
1
vote
2answers
895 views

5v output to 3.3v?

I have a microcontroller and a Raspberry Pi, both running off of the same 5v supply, in parallel. The microcontroller has 4 5v output pins and the other is a Raspberry Pi, that can only accept inputs ...
1
vote
1answer
544 views

Will this schematic work?

Newbie here, trying to learn electronics (Iam from SW background). Looking for someone to review the initial schematic and advise. Haven't ordered the parts yet, so appreciate any tips in finalising ...
8
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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 ...
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 ...
3
votes
2answers
3k views

How long will a battery last based on these numbers

Hi I asked this question on SU but seemed to have gotten into a bit of trouble, I was referenced here. I am getting into doing hardware build based on things like microcontrollers and microprocessors....
2
votes
2answers
7k views

Raspberry Pi + IRFZ44N to control a 5050 RGB LED strip: current seems to be limited

Introduction and General Question: Scalability I have assembled very simple circuitry to successfully control one RGB LED strip. I have also managed to improve slightly its yield. However, when I ...
1
vote
3answers
1k views

Convert 9v of battery into 5v at 3.5watt

I want to run Raspberry Pi using a general non-rechargeable 9v battery. Raspberry Pi needs 3.5W and 5V input. Questions: Which LDO should i use ? For what amount of time general 9V battery is able to ...
3
votes
2answers
1k views

Raspberry Pi and USB modem - can I connect it like this?

As some of you know - Raspberry Pi model B has only 100mA available on USB ports. I want to connect USB modem (that takes > 500mA sometimes) to my Raspberry without powered USB hub. I have: ...
1
vote
5answers
754 views

How to measure voltage of a floating GPIO (Raspberry Pi)

I would like to measure that voltage of a floating GPIO on a Raspberry Pi 3. When I use a multi meter or an oscilloscope it looks like the pin is pulled to ground and shows 0. Another way of asking ...
1
vote
1answer
433 views

Smart Phone's camera socket

I just want ask how the socket in the image is called? I couldn't really find and the closer I could get is only Raspberry's module.
0
votes
1answer
440 views

How to measure bipolar analog signal accurately (to 1mV) on raspberry pi

BACKGROUND This is my first question on Stack Exchange so apologies for any missteps. I'm currently working on a project measuring tilt outputing an analog signal that ranges from -2V to 2V. But the ...
0
votes
2answers
2k views

How to use a Raspberry Pi Pin(3.3V) to reset a ATMEGA328(5V)

I have a ATMEGA328(AVR) connected to a Raspberry Pi(RPI) via serial using a level shifter. The AVR has the Arduino Bootloader installed and I would like to program it via serial. What would be the ...
0
votes
1answer
510 views

Integrating momentary switch with a Raspberry Pi

Please note: Although my question involves a Raspberry Pi, this is a pure electronics question at heart. I'm trying to figure out how I can wire this illuminated momentary switch to my Raspberry Pi 1 ...
0
votes
3answers
3k views

RaspberryPi + FET LED lighting controller

I'm attempting to control an LED Lighting Strip from a RasperryPI GPIO pin. I have the following setup: simulate this circuit – Schematic created using CircuitLab This is the diagram I have ...
-1
votes
3answers
788 views

Controlling a Solenoid With Raspbery Pi GPIO Output Using a Transistor

I'm trying to control a solenoid using the RasPi 2's GPIO pins. Since the solenoid needs more power than the RasPi can provide, I'm using a 9V battery to provide the power. I started with just wiring ...
9
votes
5answers
13k 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
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) ...
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?
5
votes
5answers
20k 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 \$...
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 ...
5
votes
4answers
8k 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 ...
3
votes
4answers
18k views

How to modify DS1307 RTC to use 3.3V for Raspberry Pi?

I bought DS1307 RTC but it is 5V so it can't be connected to the Pi. I know it can be modified to use 3.3V by removing 2 resistors. This sensor is different than the adafruit kit so I am not sure ...
1
vote
4answers
10k views

How to connect Raspberry Pi to House Alarm Serial Bus (DSC Keybus)

I have a DSC 1864 House Alarm and I want to connect up my Raspberry Pi's GPIO to the Keybus (a serial data communication protocol used by the alarm). I would say my knowledge of electronics is novice ...
-2
votes
2answers
3k views

How can I clone an RF transmitter? [closed]

I have a gas fireplace that is controlled via a RF transmitter/receiver that operates at 303.8MHZ. According to the manual, each remote has a unique code (1 out of 1,048,576) that is set at 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 ...
4
votes
1answer
3k views

Manual SPI interface on Raspberry PI

I am trying to control a MCP4131 digital pot from my Raspberry Pi using this library. Using the GPIO pins, I am "emulating" an SPI interface. I bring the ChipSelect pin to low, write my byte, then ...
4
votes
2answers
6k views

Is a N-Channel Mosfet save/reliable for level shifting UART from 3V3 to 5V?

I am busy with a design that needs to connect a Raspberry Pi to an Arduino via UART. Previously I have designed a circuit that worked okay. (source: protoneer.co.nz) But now I want start using SMD ...
4
votes
2answers
6k views

Powering multiple devices from a single power supply

I am learning electronics on my own and have been having a lot of fun. I am currently working on creating a Nerf sentry gun for fun with my son. I am at a point there where I need to power multiple ...
4
votes
3answers
6k views

easy to construct FM low-pass or band-pass filter

Suppose I wanted to filter a Raspberry Pi's (or other similar) GPIO digital output (running pifm or rpitx or similar) to be clean enough to not splatter RF harmonics outside of FCC Part 15 (or ...
3
votes
2answers
2k views

Extra spacing between some traces and the ground plane

I have seen several designs where there is extra spacing between some traces and the ground plane. For example, see the traces between the points A and B or C and D in the following picture (this is a ...
3
votes
1answer
2k views

Externally Powered USB Port

I have a Raspberry Pi and it requires a Externally Powered USB hub to run Portable HDD on it. So what if I connect +5 and GND port of the USB Client to external power source of 5V-1A directly rather ...
3
votes
3answers
5k views

Simple circuit with transistor using Raspberry Pi

I'm trying to use a Raspberry Pi to control a set of 4 LEDs. I'd like to control the LEDs in software by using a ...
2
votes
2answers
2k views

How do I get 5V for a Raspberry Pi from 4 D batteries?

I'm hoping to run a Raspberry Pi and a hobby servo off 4x1.5V D size Alkaline batteries. The batteries are brand new and at the moment I am measuring 6.5V from the 4 in series. I'm guessing each cell ...
1
vote
1answer
995 views

AVR ISP-Programing LEDs SCK

I'm using a Attiny45 microcontroller and USBtinyISP as my programer, and this is the first time I need to hook stuff up (in this case just LEDs, but eventually I'll want to conect a raspberry pi) to ...
1
vote
1answer
4k views

Interfacing Raspberry PI to HoneyWell alarm system (3V vs 12V)

simulate this circuit – Schematic created using CircuitLab I've been working on a similar project as this but with a HoneyWell alarm system. I've managed to lower the voltage from the 12V or ...
1
vote
2answers
3k views

Connecting a Raspberry Pi to a 220V switch

I have a switch that works at 220-230V AC and I'd like to link it to my Raspberry Pi and I want to know what I have to do from an electrical point of view. So my switch, when switched on, places 220V ...
1
vote
2answers
3k views

Sensing weight with strain gauge, InAmp, ADC & Pi

I have an SEN-10245 sensor for weighing objects (essentially a strain gauge). The goal is to capture data with a Raspberry Pi, so the signal from the weight sensor needs to be amplified and then ran ...
0
votes
1answer
62 views

Circuit changes, what is the input high and low given when the circuit is lit and not!

One change in the circuit, the R1 is not 4300 ohms but instead 4700 ohms. The voltmeter is the input into the raspberry pi GPIO board. What would be the input (voltage) when light gets to the ...
0
votes
3answers
4k views

How to design an optocoupler circuit for raspberry pi

I want to give sensor pulse to raspberry pi. The sensor signal comes from a running conveyor . The sensor gives 24v signal hence I used a optocoupler to convert the 24v to 3.3v . How should I design a ...
0
votes
3answers
914 views

Splitting mains power into multiple relay-switched circuits

Summary Introduction My goal is to split a 1-gang mains power extension lead into three, have my Raspberry Pi plugged into one of the outputs, and have the Pi able to switch the other two outputs ...