Go to advanced search

by knute
Wed Apr 15, 2015 11:49 pm
Forum: C/C++
Topic: C pigpio DHTXX sensors
Replies: 8
Views: 1712

C pigpio DHTXX sensors

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...
by knute
Wed Apr 15, 2015 11:11 pm
Forum: Java
Topic: UDP receive buffer size?
Replies: 9
Views: 6805

Re: UDP receive buffer size?

Thanks, I'll try that.
by knute
Sat Apr 11, 2015 3:40 am
Forum: Java
Topic: UDP receive buffer size?
Replies: 9
Views: 6805

Re: UDP receive buffer size?

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"...
by knute
Sat Apr 11, 2015 3:36 am
Forum: Java
Topic: UDP receive buffer size?
Replies: 9
Views: 6805

Re: UDP receive buffer size?

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?
by knute
Fri Apr 03, 2015 4:10 am
Forum: Java
Topic: UDP receive buffer size?
Replies: 9
Views: 6805

Re: UDP receive buffer size?

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...
by knute
Wed Apr 01, 2015 3:49 am
Forum: Java
Topic: UDP receive buffer size?
Replies: 9
Views: 6805

UDP receive buffer size?

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...
by knute
Mon Mar 09, 2015 3:19 am
Forum: Java
Topic: Could not initialize class gnu.io.CommPortIdentifier on tomc
Replies: 7
Views: 4729

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

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...
by knute
Fri Mar 06, 2015 5:27 am
Forum: Beginners
Topic: Send an email when raspberry pi is connected to the internet
Replies: 11
Views: 3068

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

Write a program...

What is controlling whether or not the Pi is connected to the internet? Is the connection dodgy?
by knute
Sat Feb 21, 2015 4:52 am
Forum: Troubleshooting
Topic: Pi2 boot problem?
Replies: 2
Views: 596

Pi2 boot problem?

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...
by knute
Fri Feb 20, 2015 3:56 am
Forum: Raspberry Pi OS
Topic: Pi2 error dialog when starting X?
Replies: 3
Views: 1004

Re: Pi2 error dialog when starting X?

OK
by knute
Thu Feb 19, 2015 5:31 am
Forum: Raspberry Pi OS
Topic: Pi2 error dialog when starting X?
Replies: 3
Views: 1004

Pi2 error dialog when starting X?

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...
by knute
Sun Dec 21, 2014 5:49 pm
Forum: Raspberry Pi OS
Topic: fullscreen analog clock?
Replies: 8
Views: 9501

Re: fullscreen analog clock?

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...
by knute
Sun Dec 21, 2014 1:28 am
Forum: Raspberry Pi OS
Topic: fullscreen analog clock?
Replies: 8
Views: 9501

Re: fullscreen analog clock?

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...
by knute
Fri Dec 19, 2014 4:23 am
Forum: General discussion
Topic: Good Wireless Keyboard????
Replies: 8
Views: 2558

Re: Good Wireless Keyboard????

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 ...
by knute
Thu Dec 18, 2014 4:13 am
Forum: Troubleshooting
Topic: can't ssh
Replies: 3
Views: 733

Re: can't ssh

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.
by knute
Sat Dec 13, 2014 3:28 am
Forum: Graphics, sound and multimedia
Topic: Simply play a slideshow of images from a network drive
Replies: 4
Views: 2103

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

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.
by knute
Thu Dec 11, 2014 4:00 am
Forum: Python
Topic: basic image processing module
Replies: 15
Views: 2537

Re: basic image processing module

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?
by knute
Tue Dec 09, 2014 1:52 am
Forum: General discussion
Topic: Up To date guide needed - How do i access Raspberry Pi from
Replies: 6
Views: 1031

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

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...
by knute
Wed Nov 26, 2014 2:47 am
Forum: Java
Topic: JavaFX?
Replies: 5
Views: 1764

Re: JavaFX? - Solved more or less

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. ...
by knute
Wed Nov 26, 2014 1:16 am
Forum: Java
Topic: JavaFX?
Replies: 5
Views: 1764

Re: JavaFX?

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,
by knute
Wed Nov 26, 2014 12:42 am
Forum: Java
Topic: JavaFX?
Replies: 5
Views: 1764

Re: JavaFX?

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.
by knute
Wed Nov 26, 2014 12:11 am
Forum: Java
Topic: JavaFX?
Replies: 5
Views: 1764

Re: JavaFX?

I'll try increasing the memory and report back.

Thanks for the book recommendation, I ordered it.
by knute
Tue Nov 25, 2014 1:27 am
Forum: Java
Topic: JavaFX?
Replies: 5
Views: 1764

JavaFX?

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,
by knute
Sat Nov 22, 2014 5:32 pm
Forum: Java
Topic: Improve drawing performance?
Replies: 2
Views: 929

Improve drawing performance?

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 ...
by knute
Wed Nov 12, 2014 3:03 am
Forum: Troubleshooting
Topic: Android VNC Connection.
Replies: 2
Views: 891

Re: Android VNC Connection.

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...

Go to advanced search