Hot answers tagged

11

Yes, every electronics degrades while it ages, if connected on some power source. The "problem" lies in electronic characteristics itself. One of the phenomena is called electromigration, where IC (actually whole PCB) degrades under various "nonideal" (i.e. working) conditions: current, time, temperature (which is also consequently caused by resistance ...


8

There's software in the repository exactly for this purpose: $ apt-cache search apcupsd apcupsd - APC UPS Power Management (daemon) apcupsd-cgi - APC UPS Power Management (web interface) apcupsd-doc - APC UPS Power Management (documentation/examples) The correct solution to this common problem would be getting a good APC UPS, connecting all your network ...


6

Only power the Pi from a 5V power supply. Don't make connections to the pins on the expansion header when the Pi is powered. It is easy to short a pin to an adjacent pin which might cause a damaging short-circuit. Don't connect a voltage less than 0V or greater than 3.3V to the Pi's gpios. Be especially careful if connecting a device which is powered ...


6

All USB keyboards are 5V. No matter how big or how small, they always use 5V power as supplied by the USB port. However, different devices draw different amounts of current. A typical USB port provides 500mA of current, and the Raspberry Pi (model B) draws between 300mA and 700mA (depending on processor load). Try to keep the current used by USB devices to ...


5

You could do this via the /etc/hosts file, however, this method can be easily over-ridden with the right knowledge and file access. Beyond the /etc/hosts file, there are two methods that I know of, both using Proxys. These answers were originally for Ubuntu, but they should work just the same on Raspbian (or possibly with a bit of modification,) as both ...


4

Like you said, you will need a battery to support the pi after the outage. After you have that setup, take a GPIO pin, and wire that up so it has 3.3v to it when the power is on, and 0v to it when the power is off. Make sure you include a pull down resistor to force that pin to 0v when no current is applied. There are a number of ways to do this, but a ...


4

You can wait for all the LED's to go off. Only the red LED(power LED) stays on. That's when the Pi has shutdown


4

To further elaborate on the why not for some of the things: don't plug in an electric motor directly: controlling one is fine, but if it is connected directly, the Pi has nowhere near enough power to run it, and can be destroyed if the motor is spun and acts like a generator, sending power into the pi. don't plug stuff in while the pi is running - while ...


4

It is reasonably safe if you are sensible. The MOST IMPORTANT thing is NOT to connect anything >3.3V to a pin. Make sure you don't connect the 5V! In general you should avoid making connections with the Pi running (at least until you get more experience). You should try running a LED (through a resistor - say 470Ω). Connecting push buttons is pretty safe (...


4

Yes. In fact this is normal engineering practice, although for the Pi it probably makes no difference as the outputs are symmetrical. Having said that the amount of current you can supply from 3.3V is limited.


4

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, it's the common ground. It also does not "use up", i.e. you can use it multiple times over. Which is part of your linked picture at raspberrypi.org. Both ...


4

I am interpreting the picture of the printed circuit board of the relay module with accompanying notes as follows: the board includes a transistor and a diode - and while it is impossible to tell from the image without looking at the wiring and/or schematics - it is reasonable to believe this is the freewheel diode you're refering to. Conclusion here: no ...


4

The Relay module in your picture is what so called Relay shield specific designed for directly interfacing with micro controller such as Raspberry Pi or Arduino, the board already consists of the protection diode and switching transistor and active/disabled LED indicator. You can connect 5v, GND, and GPIO directly to VCC, GND, and IN at the shield. To ...


4

The Pi data states 5±0.25V; the MxL7704 PMIC Data states Input voltage range: 4.0V to 5.5V so NO If your 6V UBEC is producing 8V I would throw it in the bin!


3

The simplest thing to do is power it from 3V3. Even if you powered from 5V it would be okay as long as the device contains no pull-up resistors for the I2C bus. Tu use the device connect it to 3V3, ground, SDA, and SCL and make the following entry in /boot/config.txt dtoverlay=i2c-rtc,ds3231


3

I really have no idea how that RTC clock operates, but I can give you some info that might help you... The I2C bus is designed in such a way that the I2C master (the RPi in this case), is what drives the voltage (brings it high, which would be 3V3 for the RPi). I2C slaves (the RTC clock here) "send" data by bringing the data line low (GND). So frying the ...


3

When the pi is at halt but still powered you're fine. With no power to the pi, I would recommend making sure that there is no power leaking into the GPIO. It probably won't toast things, but the GPIO do connect directly to the Broadcom SoC with no buffering. So there is a chance of breakage.


3

Yes it is safe to connect without a resistor. As for which is better a piezo disc or buzzer. There is not much difference (one may be louder than the other for the same voltage, and the may differ in tone), but only experimenting will tell you if there is enough difference to care.


3

It is generally not possible to power a HD from the Pi, which has only limited current (depending on what else is connected), due to the polyfuse. Connecting to a USB PS will attempt to backpower the Pi. I recommend a powered hub, but even in this case some will backpower. It is not a good idea to connect a backpowering hub at the same time as a PSU. You ...


3

The Raspberry Pi does not allow you to shut it down completely, unless you unplug the power. The best way to turn it off is by running sudo shutdown -h now and waiting until everything has been unloaded properly and then unplugging the device. If you have no display I would recommend that you run the command and then wait a few minutes until you unplug the ...


3

There is no simple answer for your question. What do you mean by secure? Why it should be safe by default? It is as secure as your operating system and probably your router (I assume that you have integrated some simple FW there) and of course your Appache instance and web service you are developing. There are really many factors that makes your system ...


3

Yes it's possible. Cooling will not be a problem, in fact, most potting compounds have higher thermal conductivity than air (e.g. this special compound outperforms air by a factor of 30, 10 being more common for cheap compounds such as silicone or butalene rubber). There are however a few things to watch out: Curing by-products. Compounds which are not ...


3

Yes, it is called sinking current rather than sourcing current. I have used it myself with LEDs on the Pi. The control is reversed. To switch the LED on you write 0 to the GPIO. To switch the LED off you write 1.


2

You can buy small aluminium plates and glue them carefully with a super-conductive glue to the chips. Then you can plug cables to all the connectors and glue the whole device into epoxy. Epoxy itself is dielectric so you should be safe. However, you can still encounter several problems: The heat/cooling and stabilisation of epoxy can damage some parts of ...


2

A low cost solution is to use a USB battery pack. A decent battery can power a pi for a number of hours depending on usage and battery capacity. Here's an example of a DSL modem charging a battery that is powering a pi. In the example, the modem can reset and the pi won't get interrupted. The battery needs to be rated at 5v and have a high enough input and ...


2

I'm a little late to answer, but my solution only involves two simple command issued from the console (one to turn the volume up, one to turn the volume down). It require only a little setup, and the use of aliases. Make sure you are in the user folder: $ cd ~/ Create the file .bash_aliases (this will be where I keep all the aliases I make so they aren't ...


2

I really wonder why you state that you cannot find any summary as to how to safely operate the Pi's GPIO. But nevertheless it's a good idea to check and double check before frying the fragile pins... A first stop should be the official website of the Raspberry Pi Foundation: namely this and the usage section linked there. Another helpful place is elinux.org ...


2

Based on looking at the schematics in the Ebay listing and a perusal of the images of the board itself, you should be able to power this from the 3.3V rail on the Pi without incident. Both devices list 3.3V operation or have operating voltage ranges that include 3.3V. Schematic: Board view: Datasheet for the DS3231: http://datasheets.maximintegrated.com/...


2

I run two Pi2s and a Pi3 headlessly (i.e. remotely, with no monitor/keyboard) and they're left on 24/7. The Pi devices are great for this type of use-case as they use a fraction of the energy of a full-size computer. If you have a Pi3 and you'll be leaving it doing very long CPU-intensive tasks, you'll want to use a heatsink and maybe a fan, but it's only ...


2

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 on each used GPIO.


Only top voted, non community-wiki answers of a minimum length are eligible