Raspberry Pi Forums

davidcoton

Alternatively, incorporate a hardware delay between the GPIO and the PSU shutdown transistor. Make it long enough for the Pi to shutdown normally before the PSU is cut. It is simpler (and probably safer) that trying the get the software solution right.

davidcoton

How do you intend a script to invoke reboot and resume itself after the reboot?

davidcoton

What have you tried?
What did you see happening?

davidcoton

I just need the maximum speed as possible in my C program (I am not interested in linux features). What I do not know is that despite rasperry pi spending time in OS would be still faster than a powrfull microcontroller (arduino due or other one). 1) Try it and see. 2) I would be very surprised if ...

davidcoton

Woll wrote: Did the millions, billions and trillions come in with decimisation? Are they SI units?

AFAIK, no and no.

davidcoton

I'm afraid I can't explain why your Pi should stop working, whether the circuit trip was involved or just coincidence. It's worth trying a better PSU (5V 2A) and cable before replacing the Pi, just because the cases reported here have frequently been resolved by that. But the checks you have already...

davidcoton

A circuit breaker trip and reset is unlikely in itself to cause destructive conditions for connected equipment. Any mains disturbance that could occur is similarly unlikely to damage anything except the PSU. It is possible that a severely damaged PSU could in turn damage the Pi, but if the PSU is wo...

davidcoton

What do you think might be a problem? Any switch that can handle the PSU current (2A) will work. Of course you have to shut down the Pi before switching off, and unless you are building a PSU into the console your switch will only control the 5V PSU output, so you really should unplug (or switch off...

davidcoton

Have you got a Win dows Explorer pne open with the sdcard showing? IIRC that can cause the "in use" error.

davidcoton

hmmmm... do you recommend i start small in my goals maybe make an application to start with, like starting small then increasing what i do as i learn languages? Absolutely, if you were learning to swim you wouldn't start with swimming from England to France. Writing applications is the way to learn...

davidcoton

Do you have any USB peripherals connected? USB hard disks in particular can have a high start-up current, which causes a short voltage drop. I'm not sure why the Ethernet connection would make a difference, though -- possibly the driver happens to do something critical just as the HD starts.

davidcoton

I think the "RCB (sic) icon" is the rainbow square in the corner. It is a low voltage warning. You may need a better power supply (5V 2A recommended) and/or cable from PSU to Pi.

davidcoton

You may already know some of what follows, but I'm trying to keep this reply reasonably broad and comprehensive in the hope that it may inspire not only you but others with different background and experience. I'm assuming you are not a professional software engineer, but I'm going to suggest things...

davidcoton

Thanks -- that fixed it! Another black mark for phpBB, I'm afraid -- though I know it's not an easy thing to code.

Just for reference, I'm running Win Vista with latest mainstream Firefox.

davidcoton

The board appears to be recording post times in BST. Surely it should be GMT/UTC -- at least through the winter period when GMT is used in the UK, and arguably all year.

davidcoton

Another idea:
Use another Pi to send the LAN message. Write the message send routine to pulse a GPIO just after the message is sent. Time from that pulse to the receiving Pi's output.

davidcoton

Thinking laterally: Modify your program to include a logging facility. Write a timestamp when the LAN message is received. Write another after the GPIO is set. Afterwards, read the log file and do the maths. That will measure the latency in your software. It will miss any (variable) latency due to L...

davidcoton

Are you pressing SHIFT "A" not just "a" ?

What version of Python?
My code or yours?

davidcoton

If there is such a project, Google probably knows.

davidcoton

Your description is not entirely clear. But if it is a relay with an interface board, is "12V" the relay contact rating or the coil rating? One of the (not well focussed) images seems to show a coil rating of 12V but I can't read it well enough to be certain. Possibly the relay interface board needs...

davidcoton

Well, with a bitr of work to correct the indents and put tkinter all lower case, this worked for me on Windows (Python 3.4.3) import tkinter class Main(object): def __init__(self, master): self.master = master self.widget = tkinter.Text(master) self.widget.bind('A', self.event) self.widget.pack() de...

davidcoton

fruit-uk wrote:I'd rather have fish and mc installed as default

Surely we want Pi and chips, not fish and mc.

davidcoton

It looks like a college assignment. We are not a homework service -- your academic work must be your own.

Of course, if you try something and can't quite make it work, you're welcome to ask about that.

davidcoton

Beg,borrow or buy a digital voltmeter, if you don't already have one. Monitor the 5V supply at the Pi. See if it really is 5V or if it drops on load -- for example, unplug the WiFi dongle and check whether the voltage rises without it. Low voltage is due to either a poor supply or too thin conductor...

davidcoton

What have you tried and what went wrong? Please post your code so we can look for problems. (Use the "Code" tags in the message editor.)

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