Raspberry Pi Forums

knute

I haven't programmed C in a couple of decades but I'm probably more familiar with it than Python. So when I went looking for some example C code to read the DHTXX sensors I couldn't find much. The one piece of code that I found used wiringPi worked but it got a lot of failed reads and so I was looki...

knute

Thanks, I'll try that.

knute

Having a larger buffer is a simple solution to prevent buffer overrun and loss of data. Surely you must already cope with missing (and duplicated or reordered) data, since you are using UDP, which does not guarantee delivery in the first place. Yes, I send it again shortly. [quot="jojopi"...

knute

DougieLawson wrote:
knute wrote: So does anybody actually know how to make the UDP buffer larger?
Five seconds spent googling turns up
sysctl -w net.core.rmem_max=2097152

Thanks for that. Now I know why it didn't work when I tried it before. It doesn't persist after a reboot. Is there a way to make it stay?

knute

Our server ultimately has to serve data to as many as 2000 sites. More full up socket connections than we want to have on a PC. There are periodic record bursts that are 1MB. The holdup in the Pi appears to be reading the data from the buffer into my program. Having a larger buffer is a simple solut...

knute

I'm testing a Java program on my A+ and I would like to set the socket receive buffer size to 2MB but using Socket.setReceiveBufferSize(1024*2048) gives me a buffer size of 163840. The default is 81920. Is there another way to increase the buffer size with an OS option somewhere?

Thanks,

knute...

knute

The -cp option is ignored if -jar is specified. -jar filename Executes a program encapsulated in a JAR file. The filename argument is the name of a JAR file with a manifest that contains a line in the form Main-Class:classname that defines the class with the public static void main(String[] args) me...

knute

Write a program...

What is controlling whether or not the Pi is connected to the internet? Is the connection dodgy?

knute

My new Pi2 occaisionally fails to boot. It produces a lot of error messages but a couple are repeated: WARNING: CPU: 2 PID: 55 at drivers/mmc/host/bcm2835-mmc.c:476 mmcblk0: unknown error -5 sending read/write command, card status 0x900 The green light that usually flashes during boot comes on solid...

knute

knute

So I just got my Pi2, loaded up an SD card with the lastest Raspbian image (2015-02-16) and booted it up. Had a few problems that I think are SD card related so I programmed another one and it appears to be more stable. When I start X for the first time after a boot, I get a dialog with the followin...

knute

Oh goody! I get to learn to work in yet another programming language! lol :lol: Seriously, though, I have a feeling that this is probably going to be what I am looking for. Off I go to read a couple of books real quick ;) Thank you! It may take a little while for me to be able to take a look it thi...

knute

How about a Java analog clock? import java.awt.*; import java.awt.event.*; import java.awt.geom.*; import java.util.*; import javax.swing.*; /** * AnalogClock is a resizable Swing component that draws an analog clock. * * @author Knute Johnson */ public class AnalogClock extends JComponent implement...

knute

I bought a Gear Head 2.4Ghz wireless touch keyboard at Fry's the other day. It has a USB dongle that communicates with the keyboard/touchpad. It works well enough, with the occasional hiccup. The keyboard is really too small for my fat fingers, I have to use one finger at a time. I bought it to use ...

knute

I'm not an iptables expert and I don't use it anymore since ufw is so easy but it looks to me like you don't allow any NEW connections.

knute

I've got a simple little Java program that will sequence through images in a directory. Even does a crossfade between them. I have no idea what a secure kiosk mode is though.

If you want the code I'll post it tomorrow when I can get at my laptop.

knute

You are going to run into some interesting artifacts by scaling an image to 8x8. I'm not a Python programmer so I can't help you with that but it is a simple task in Java to scale an image. What do you need in the end, the RGB values of the 64 pixels?

knute

Enable SSH from raspi-config , select item 8, Advanced Options and then A4, Enable SSH. sudo raspi-config Install VNC sudo apt-get install tightvncserver run: tightvncserver as pi, not root, to set up passwords. You don't need the second password. start the server with: vncserver :1 -geometry 1920x1...

knute

So I solved most of my problem, and that is because I was using VNC to look at my Pi desktop not looking at it directly. Apparently JavaFX apps don't run in the same way as Swing apps. They use some sort of full screen/framebuffer mode? Any way my app runs but without the normal windowing features. ...

knute

Both Pis have same problem, just hang. I've tried setting 256MB video memory, I've tried three different SD cards but all with Raspbian and two versions of Java, 1.8.0 and 1.8.0_6. Swing programs run great but FX programs just hang.

I'd love some ideas?

Thanks,

knute

256MB memory didn't help, it still hangs with no errors or output of any kind.

I must have something not configured correctly. I've got another Pi, I'll try that one and see if it is any different.

knute

I'll try increasing the memory and report back.

Thanks for the book recommendation, I ordered it.

knute

Anybody got JavaFX running on their Pi? I've got 1.8.0_u6 installed and I can compile the program but I can't even get a simple HelloWorld app to run. It just hangs. A little help?

Thanks,

knute

I realize that the Pi has limited processor power but I'm looking for a way to improve the drawing speed of some images. I'm working on a program that draws multiple images in rapid succession. I understand the Pi has a GPU and I've seen some pretty cool 3D action done with it. Does anybody know if ...

knute

Guys. Hi. I am like stuck in this situation since many days. I've set a static ip for rpi in cmdline.txt. it's set to 169.254.1.1 I've set up tightvncserver properly. Also, ive allowed My note 3 tether to be shared with the windows 7 laptop which is connected with rpi via lan cable. But, i can't us...

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C pigpio DHTXX sensors

Re: UDP receive buffer size?

Re: UDP receive buffer size?

Re: UDP receive buffer size?

Re: UDP receive buffer size?

UDP receive buffer size?

Re: Could not initialize class gnu.io.CommPortIdentifier on

Re: Send an email when raspberry pi is connected to the inte

Pi2 boot problem?

Re: Pi2 error dialog when starting X?

Pi2 error dialog when starting X?

Re: fullscreen analog clock?

Re: fullscreen analog clock?

Re: Good Wireless Keyboard????

Re: can't ssh

Re: Simply play a slideshow of images from a network drive

Re: basic image processing module

Re: Up To date guide needed - How do i access Raspberry Pi f

Re: JavaFX? - Solved more or less

Re: JavaFX?

Re: JavaFX?

Re: JavaFX?

JavaFX?

Improve drawing performance?

Re: Android VNC Connection.