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by tedhale
Wed Nov 07, 2012 7:08 pm
Forum: Off topic discussion
Topic: What are your Other Hobbies / Interests??
Replies: 72
Views: 10933

Re: What are your Other Hobbies / Interests??

With a technical job and several technical hobbies, I have to have something non-technical to do occasionally to keep my sanity. The best thing is hiking and camping, but I really only get to do that a few times a year. I am a home-brewer and have been making my own beer for over five years. But my ...
by tedhale
Mon Nov 05, 2012 2:04 pm
Forum: Networking and servers
Topic: RPi to RPi TCP connection
Replies: 25
Views: 6893

Re: RPi to RPi TCP connection

the command netstat -a | grep LISTEN will show the ports that are currently being listened on. Just choose a port that is not a commonly used port. The file /etc/services lists a lot of the common ports. Use something above 10000 and you are usually safe. Question - do these systems need to move fro...
by tedhale
Mon Nov 05, 2012 1:49 pm
Forum: C/C++
Topic: Slight delay when writing to file
Replies: 11
Views: 2275

Re: Slight delay when writing to file

fflush(fp);
by tedhale
Fri Nov 02, 2012 4:43 pm
Forum: Beginners
Topic: password
Replies: 2
Views: 622

Re: password

Since the password files are in /etc they are only available once the second partition is loaded. That is, they are not in /boot, so you can't see them when you load the SD card on a Windows system. The way the I would fix it is to put the SD card into a Linux machine, mount the second partition, an...
by tedhale
Fri Nov 02, 2012 1:55 pm
Forum: Beginners
Topic: Alternative method of powering a raspi
Replies: 4
Views: 1224

Re: Alternative method of powering a raspi

Doing that will bypass the fuse, so it would be a good idea to add one between the PS and the GPIO pins.
That is what I am doing.
by tedhale
Fri Nov 02, 2012 1:54 pm
Forum: Advanced users
Topic: Power constant + ignition
Replies: 3
Views: 2043

Re: Power constant + ignition

You might want to look at this thread for some ideas. http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=8820&start=25&hilit=auto+power+turn+on The RasPi does not have a clock in it, nor does it have any other volatile information that needs power to maintain. So there is no need to keep it powe...
by tedhale
Mon Oct 29, 2012 3:16 pm
Forum: Troubleshooting
Topic: Record USB audio input
Replies: 31
Views: 33361

Re: Record USB audio input

Your existing RasPis will be fine. You will need to update the firmware and install a new kernel (well, probably just flash the new one) and be good to go. Hopefully with less noise. (at least, once they fix the async USB problems.)
by tedhale
Mon Oct 29, 2012 2:59 pm
Forum: Troubleshooting
Topic: Screen Size
Replies: 4
Views: 803

Re: Screen Size

You say you can't save the file once edited. Perhaps that is a permissions problem.
The "pi" user does not have permissions to do this - you have to do it as root.

You can get around this by using the "sudo" command to run the command as root.
Try:
sudo nano /boot/cmdline.txt
by tedhale
Mon Oct 29, 2012 1:12 pm
Forum: Beginners
Topic: putty exits when user logs on except for pi
Replies: 2
Views: 589

Re: putty exits when user logs on except for pi

The adduser script should have set everything up OK, but something is obviously wrong. It sounds like the password is accepted, so the user is not locked out. The first thing that comes to mind is that the new user does not have a valid shell defined. do this: cat /etc/passwd and look at the line fo...
by tedhale
Fri Oct 26, 2012 2:04 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: GPIO via bash??
Replies: 6
Views: 26796

Re: GPIO via bash??

Thanks, I just managed to toggle my GPIO pin via bash with the minimum amount of effort without the need of a compiler. :) I guess if I wanted to implement this in Free Pascal all I need to do is treat the GPIO pins as if I was to read / write files or am I wrong?? Richard S. Yes. That is all that ...
by tedhale
Fri Oct 26, 2012 1:43 pm
Forum: General programming discussion
Topic: Best way to start shell script on startup?
Replies: 10
Views: 5743

Re: Best way to start shell script on startup?

/etc/rc.local

is for misc startup stuff. But it does sound like you might want to crontab a script
by tedhale
Tue Oct 16, 2012 3:47 am
Forum: Automation, sensing and robotics
Topic: Home alarm system retrofit.
Replies: 36
Views: 20483

Re: Home alarm system retrofit.

Updated the source code post on my blog with a few corrections. Also, the GPIO poller code supports the multiplexed input.

Also added a new post with a picture of my interface. It is nearly complete.
by tedhale
Tue Oct 09, 2012 2:39 pm
Forum: Automation, sensing and robotics
Topic: Home alarm system retrofit.
Replies: 36
Views: 20483

Re: Home alarm system retrofit.

I have a post on my blog now with some of my source code describing:

- How to make a daemon process in C
- How to use background threads
- My data structures
- My GPIO polling thread

at the address in my sig block below.
by tedhale
Tue Oct 09, 2012 1:09 pm
Forum: Arch
Topic: Getting serial console to respond in Arch/ARM
Replies: 21
Views: 27601

Re: Getting serial console to respond in Arch/ARM

Thanks for the correction. Once again showing what an old fart I am (though I did say I wasn't familiar with the distro.) A lot of my experience is with Debian and Ubuntu, so Raspbian seemed the best choice for me to start with. It still amazes me how quickly the number of choices is growing for the...
by tedhale
Tue Oct 09, 2012 1:03 pm
Forum: Troubleshooting
Topic: How to get case?
Replies: 6
Views: 1607

Re: How to get case?

Looks like my post with pictures didn't make it.
trying again.

A functional and dirt cheap case.

Image


Image
by tedhale
Mon Oct 08, 2012 8:16 pm
Forum: General programming discussion
Topic: Easiest way to discover other RPs on the network?
Replies: 9
Views: 3403

Re: Easiest way to discover other RPs on the network?

The way I have done discovery in the past is something like this: Do a UDP broadcast of a "who's there?" message on a specific port. A broadcast goes to all addresses on the LAN as defined by the netmask. Then just listen to the responses come in. To make those responses happen, have your program li...
by tedhale
Mon Oct 08, 2012 6:34 pm
Forum: Troubleshooting
Topic: How to get case?
Replies: 6
Views: 1607

Re: How to get case?

And there are several folded paper designs. This one was posted on this forum recently
http://www.raspberrypi.org/phpBB3/viewt ... t=glueless

I just printed one out on card stock and will see how it goes together this evening.
I will try to post some pictures.
by tedhale
Mon Oct 08, 2012 2:01 pm
Forum: Arch
Topic: Getting serial console to respond in Arch/ARM
Replies: 21
Views: 27601

Re: Getting serial console to respond in Arch/ARM

I am not really familiar with that distro, but assuming that is is like most linux distros, you need to have a line in

/etc/inittab

that looks like this

T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100

That should make the login prompt appear automatically on boot.
by tedhale
Fri Oct 05, 2012 1:36 pm
Forum: Troubleshooting
Topic: booting headess is slower than with screen?
Replies: 3
Views: 630

Re: booting headess is slower than with screen?

If you connect to the serial port on the GPIO you can see all of the boot process. If you use something like this http://adafruit.com/products/954 you won't have to build a serial interface module. If you would like to build one anyway, there are instructions on my blog. I am curious about this sinc...
by tedhale
Fri Oct 05, 2012 1:32 pm
Forum: Automation, sensing and robotics
Topic: Home alarm system retrofit.
Replies: 36
Views: 20483

Re: Home alarm system retrofit.

I am also using one of my RasPis for an alarm/automation system. It monitors the door switches and motion detectors via GPIO input and uses X10 to control lighting. Eventually I will add temperature inputs to monitor indoors, outdoors, hot tub, and my beer fridge (I'm a homebrewer) I have had such ...
by tedhale
Thu Oct 04, 2012 4:54 pm
Forum: Automation, sensing and robotics
Topic: Home alarm system retrofit.
Replies: 36
Views: 20483

Re: Home alarm system retrofit.

I am also using one of my RasPis for an alarm/automation system. It monitors the door switches and motion detectors via GPIO input and uses X10 to control lighting. Eventually I will add temperature inputs to monitor indoors, outdoors, hot tub, and my beer fridge (I'm a homebrewer) I have had such a...
by tedhale
Mon Oct 01, 2012 2:06 pm
Forum: Automation, sensing and robotics
Topic: Project: Doorbell
Replies: 7
Views: 2391

Re: Project: Doorbell

So you do plan on using the 3.5mm audio plug.
Why bother with the amplifier chip? Is it because you want to power the amp from the RasPi?

I cheap set of *powered* PC speakers and you should be good to go.
by tedhale
Mon Oct 01, 2012 1:59 pm
Forum: Beginners
Topic: SSH Security
Replies: 4
Views: 1743

Re: SSH Security

My home firewall is built on an Ubuntu Linux system and I have SSH enabled and fully exposed to the internet and I am not worried at all. You are much safer using keys instead of passwords, but as long as you choose a strong password you are pretty safe. Moving SSHD to a non standard port is also a ...
by tedhale
Mon Oct 01, 2012 1:30 pm
Forum: Troubleshooting
Topic: Speed and Networking issue
Replies: 3
Views: 756

Re: Speed and Networking issue

Can't help you with the speed issue. Never bothers me since I use my RPis headless. To me it is just another embedded computer. As for the network not working: 1. Check that the cable you are using is good. Try it on a working PC. 2. The RPi defaults to DHCP, so see if you are getting a valid addres...
by tedhale
Fri Sep 28, 2012 3:20 pm
Forum: General discussion
Topic: What's the simple and safe way to do a "shutdown" button?
Replies: 60
Views: 66480

Re: What's the simple and safe way to do a "shutdown" button

Yes, that is just what you need to do a real "shutdown button" It is actually so simple that you don't need a breadboard, just a way to connect to two GPIO pins. Just connect a pushbutton to a GPIO pin and to ground. Confugure the GPIO pin as input and with pull-up resistor enabled. Then it will rea...

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