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by PiGraham
Mon Jul 01, 2013 7:03 am
Forum: Automation, sensing and robotics
Topic: Noob here. Can someone give me a pointer?
Replies: 5
Views: 2174

Re: Noob here. Can someone give me a pointer?

Do you just want to turn the shower on and off? You could do that with a pair of solenoid / servo valves in the feed pipes. You would need a power supply to power them and an interface (e.g. PiFace) for the Pi to switch them. Solenoid valves are commonly used in central heatings systems and you can ...
by PiGraham
Mon Jul 01, 2013 5:26 am
Forum: Python
Topic: Kaleidoscope
Replies: 6
Views: 1636

Re: Kaleidoscope

Have you looked at this? http://www.petercollingridge.co.uk/pygame-physics-simulation You would need to render the shards then use that image as texture on multiple segments. So, you need to render to texture. I don't know the details of that using Python. This may help http://comments.gmane.org/gma...
by PiGraham
Mon Jul 01, 2013 4:58 am
Forum: Python
Topic: Relays, GPIOs, and PiFace
Replies: 1
Views: 941

Re: Relays, GPIOs, and PiFace

Have you read this?
https://projects.drogon.net/raspberry-pi/wiringpiface/

Piface outputs are different to Pi outputs. Make sure you initialise correctly.
by PiGraham
Sun Jun 30, 2013 2:58 pm
Forum: Python
Topic: How do I read in Pulse Widths?
Replies: 13
Views: 6286

Re: How do I read in Pulse Widths?

How wide are the pulses?
by PiGraham
Sun Jun 30, 2013 11:14 am
Forum: Beginners
Topic: Why are GPIO input values have opposite logic
Replies: 9
Views: 1934

Re: Why are GPIO input values have opposite logic

@mntmst I am not entirely sure I understand your explanation (I don't know much about electronics), am I right in thinking this happens because of negative logic? This still seems illogical but at least it is an explanation. @aTao Thanks but the 0 for true is correct for Raspberry Pi just is illogi...
by PiGraham
Sun Jun 30, 2013 11:03 am
Forum: General discussion
Topic: Powering the Pi with 6AAs?
Replies: 3
Views: 1030

Re: Powering the Pi with 6AAs?

If the Pi draws an average of 2.5W you need >2.5WH (watt hours) to run for an hour. 2,600mAH NiCads, in top condition, could provide 2.6AH x 1.2V = 3.12Wh per cell. Six such cells potentially give you size time the energy. HOWEVER, if you waste energy in conversion, and if your circuit can't provide...
by PiGraham
Sun Jun 30, 2013 10:42 am
Forum: Python
Topic: How do I read in Pulse Widths?
Replies: 13
Views: 6286

Re: How do I read in Pulse Widths?

OK, I see what you mean. How long are the pulses? If the pulse is too short you may miss it. Assuming it's slow enough to catch you may want to look at the GPIO events. This would be vital if your program has anything else to do since the program is tied up polling for the first edge. event_detected...
by PiGraham
Sun Jun 30, 2013 9:39 am
Forum: Python
Topic: How do I read in Pulse Widths?
Replies: 13
Views: 6286

Re: How do I read in Pulse Widths?

How you measure pulses will depend on how long the pulses are, the rate ect., and how accurately do you need to measure them. For the coin slot you don;t need to measure pulses. According to Sparkfun video the unit outputs serial at 9600 baud. You need to connect the serial to the Pi UART Rx input. ...
by PiGraham
Sat Jun 29, 2013 9:37 am
Forum: Networking and servers
Topic: Need help with a Nightclub Project! Output to Multiple Tv's!
Replies: 9
Views: 2831

Re: Need help with a Nightclub Project! Output to Multiple T

There is no screncasting software for the Pi. Even AirPlay ghans The Pi can display an HD video IP stream. I assume the PC that is the source could output to a stream that is multi-cast to the network for the Pis to display. But, looking at the Edimax video mixer linked in the OP you may be right t...
by PiGraham
Sat Jun 29, 2013 8:38 am
Forum: C/C++
Topic: Serial Communication with Ethernet
Replies: 8
Views: 15187

Re: Serial Communication with Ethernet

Hi everyone, I want to use ethernet communication on my desktop with my pi. I want to learn how to do "ethernet to ethernet communication" . How can I send a data from pc to RPi ? I'm using Debian for RPi. Thanks. Lots of ways to approach this. One is to sens small packets of information using UDP ...
by PiGraham
Sat Jun 29, 2013 6:08 am
Forum: Camera board
Topic: Frame synchronisation
Replies: 82
Views: 39338

Re: Frame synchronisation

It is understandable, and reasonable, that RasPi doesn't exploit every feature. The real frustration is that the features are there but the information we would need to diy is not available. So much around the Pi is open source that the closed nature of the hardware is a stark contrast. If only it w...
by PiGraham
Fri Jun 28, 2013 10:19 pm
Forum: Other projects
Topic: Need help with a Nightclub Project! Output to Multiple Tv's!
Replies: 1
Views: 1031

Re: Need help with a Nightclub Project! Output to Multiple T

Somebody posting here has made some software that might suit. Not sure of details but I think it was called Screenly.
Someone else posted about a similar system with reference to museum information, "Pi Presents", I think.
Maybe try searching the forum for "presentation", "multicast", "RTSP".
by PiGraham
Fri Jun 28, 2013 10:09 pm
Forum: General discussion
Topic: Wiki on the front page
Replies: 3
Views: 660

Re: Wiki on the front page

I see. Thanks.
The forum is a very valuable resource, but an indexed wiki would make it far easier for people new to the Pi to find information.
by PiGraham
Fri Jun 28, 2013 1:11 pm
Forum: General discussion
Topic: See what's coming out of the HDMI through VNC?
Replies: 10
Views: 8835

Re: See what's coming out of the HDMI through VNC?

What are you trying to test? If you want to know if the video is on the HDMI output plug a screen into the HDMI. (or to DVI or VGA via an adaptor) If you have no screen why does it matter? Can't you borrow someone's HDMI TV or monitor for 10 minutes to test it? Most TVs will work with composite, eit...
by PiGraham
Fri Jun 28, 2013 11:43 am
Forum: General discussion
Topic: See what's coming out of the HDMI through VNC?
Replies: 10
Views: 8835

Re: See what's coming out of the HDMI through VNC?

I understand. But all I want to see is if there's something coming out of the HDMI port when I use omxplayer. So, from your answer, I understand that this is only possible if I plut it into a HDMI port? I can't see any information from the Pi what is actually being shown through the HDMI? The Pi wi...
by PiGraham
Fri Jun 28, 2013 9:46 am
Forum: Python
Topic: Kaleidoscope
Replies: 6
Views: 1636

Re: Kaleidoscope

I should think the rough outline would be to paint the "glitter" to a texture image that is applied to a "pie segment" shaped flat mesh and translate/rotate/mirror the mesh to various positions around the circle. Unless you want to animate the "glitter" you don't need a physics engine, and even then...
by PiGraham
Fri Jun 28, 2013 9:09 am
Forum: Automation, sensing and robotics
Topic: Raspberry Pi to toggle 3-way valve
Replies: 3
Views: 1587

Re: Raspberry Pi to toggle 3-way valve

PiFace is an easy option that provides two GPIO controlled relays and stacks neatly onto the Pi.

On Danfos solenoid coil I looked at is 7.5W AC, 9.5W DC
What voltage and current do your devices require?
Are they within the ratings of the interface board?
by PiGraham
Fri Jun 28, 2013 8:54 am
Forum: General discussion
Topic: Wiki on the front page
Replies: 3
Views: 660

Wiki on the front page

Why isn't there a link to the Raspberry Pi wiki on the front page?
by PiGraham
Fri Jun 28, 2013 8:39 am
Forum: General discussion
Topic: Remote Scrolling
Replies: 11
Views: 1436

Re: Remote Scrolling

joan wrote:I probably used xdotool.

sudo apt-get install xdotool
Solid gold Joan!
by PiGraham
Fri Jun 28, 2013 8:35 am
Forum: Camera board
Topic: Frame synchronisation
Replies: 82
Views: 39338

Re: Frame synchronisation

James, Don't take "if only the Pi did X" comments to heart. I'm sure people, when they stop to think about it, well realise that maximum functionality was not the design goal for the Pi team. It's very cheap and what we get for the money is very good. You can't really blame us for asking if it can d...
by PiGraham
Fri Jun 28, 2013 7:53 am
Forum: General discussion
Topic: Remote Scrolling
Replies: 11
Views: 1436

Re: Remote Scrolling

vonzepp wrote:Hi

I want to be able to scroll on the Desktop. Mainly the Internet Browser.
Is this a page you wrote that you can put some javascript on?
There are ways to scroll web pages:
http://www.mediacollege.com/internet/ja ... croll.html
by PiGraham
Fri Jun 28, 2013 6:52 am
Forum: General discussion
Topic: Remote Scrolling
Replies: 11
Views: 1436

Re: Remote Scrolling

I believe you can run the processes that would require a PgDn keypress (or any keyboard input) to take input from a named pipe and send a PgDn to them when required. Input to a console process comes via the process's stdin and connecting that to a pipe you can send to delivers information to the pro...
by PiGraham
Thu Jun 27, 2013 7:29 pm
Forum: Graphics, sound and multimedia
Topic: No sound from Mic
Replies: 2
Views: 1024

Re: No sound from Mic

It could be a dead mic. If you tap the mic on the table while recording, and playback at max volume, can you hear any sound at all? The problem is probably with the signal level. Many microphones produce very low signal levels, and most sound card "mic" inputs are only really suited to "line" levels...
by PiGraham
Thu Jun 27, 2013 1:47 pm
Forum: Python
Topic: The Gadget Show
Replies: 10
Views: 2250

Re: The Gadget Show

I can do that. I have a Pi with PiFace and the spec is simple.

One question, How are you interfacing the potentiometer?
by PiGraham
Thu Jun 27, 2013 7:15 am
Forum: Other projects
Topic: Assistance with making photobooth
Replies: 41
Views: 22161

Re: Assistance with making photobooth

Both Canon and Nikon DSLR shutters can be controlled by Android apps so I'm sure there must be an API available so that you can do this. Yes, there is. gphoto2 should do the job (I haven't used it). But for that to work you will have to provide external power because the camera will not sleep and w...

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