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by Redrobes
Sat Feb 02, 2013 11:54 pm
Forum: General discussion
Topic: Compile kernel modules
Replies: 13
Views: 9142

Re: Compile kernel modules

My experience is that you do have to have a) a set of kernel sources which you can download and b) a Module.symvars file which is not part of the download. I read that some people have created it and uploaded one but all the links I tried failed. To get one of these files I did build the kernel but ...
by Redrobes
Sat Jan 26, 2013 9:54 pm
Forum: General discussion
Topic: How to read data through USB
Replies: 21
Views: 25156

Re: How to read data through USB

What kind of course would require you to write embedded code in Java.... anyways, dont use USB, use the IO lines directly and avoid all the hassle of USB. Dump the data into some shift registers and use directly or drive a few lines into a microcontrollers which are hooked up to each of the servos o...
by Redrobes
Sat Jan 26, 2013 9:28 pm
Forum: General discussion
Topic: Solid sate power switch
Replies: 6
Views: 2792

Re: Solid sate power switch

Looking up a TIP126 it seems its a darlington so that maybe 0.7V is a normal figure for that type of transistor array. If I see the PDF spec sheet for it then it shows about 0.7V VCE for a 0.7A IC current. So all seems normal to me. For switching I think a FET is probably a more sensible choice.
by Redrobes
Tue Jan 22, 2013 3:15 pm
Forum: C/C++
Topic: GPIO pin mem-mapping...wait, what?
Replies: 8
Views: 4153

Re: GPIO pin mem-mapping...wait, what?

I havent read the spec but from sight reading this its saying... #define INP_GPIO(g) *(gpio+((g)/10)) &= ~(7<<(((g)%10)*3)) that when used as a macro e.g. INP_GPIO(13) then it references a memory address that is the pointer gpio (presumably the base address of all GPIO) then it seems that they are i...
by Redrobes
Tue Jan 15, 2013 5:34 pm
Forum: General programming discussion
Topic: Possible to control 16 switches with 4-5 GPIOs?
Replies: 8
Views: 1394

Re: Possible to control 16 switches with 4-5 GPIOs?

The easiest way to do this with cheap ICs is to get some shift register ICs and daisy chain them together. Then you use one GPIO pin for the signal, one to clock it onto the serial outputs. You can reset it by clocking out multiple 0's and then start clocking out the pattern you want to see on the s...
by Redrobes
Mon Jan 07, 2013 1:13 am
Forum: C/C++
Topic: Integers and Long Integers
Replies: 35
Views: 8094

Re: Integers and Long Integers

We can write a program to check how big a number a long long can hold: #include <stdio.h> #include <math.h> main() { long long ll; long double f; f = pow(2.0, 8*sizeof(ll)-1)-1; printf ("a large large is %d bytes, and can count up to %0.0lf\n", sizeof(ll),f); } First of all pow is a function that r...
by Redrobes
Mon Jan 07, 2013 12:11 am
Forum: C/C++
Topic: Integers and Long Integers
Replies: 35
Views: 8094

Re: Integers and Long Integers

There seems to be a lot of confusion here from the OP and some of the replies too. First of all, you can have an int, a short int, a long int and a long long int. The plain 'int' is guaranteed to be no longer than a long int and no shorter than a short int but its size is not defined by the language...
by Redrobes
Thu Dec 27, 2012 7:39 pm
Forum: General discussion
Topic: GIS on Raspberry Pi
Replies: 9
Views: 5999

Re: GIS on Raspberry Pi

I will be porting ViewingDale which is not GIS but is more like GeoServer to the Pi. It uses the GPU for most of the processing so with a 512Mb version and a 128Mb GPU mem split then it should work ok. Im not sure how fast it will run tho but the app is designed for slow CPU, fast GPU hardware which...
by Redrobes
Wed Dec 19, 2012 4:58 pm
Forum: HATs and other add-ons
Topic: how to sense 220v input -solved- I hope
Replies: 51
Views: 53186

Re: how to sense 220v input -solved- I hope

In an old design I had for detecting the cheap rate electricity for my home network I just nailed a neon light on the mains using the usual resistors and small neon. Then a few cm's away I put in an ORP12 light sensitive resistor (LDR) and you can tie that up to a high impedance IO like the ones on ...
by Redrobes
Sun Dec 16, 2012 6:04 pm
Forum: General discussion
Topic: Open Source H/W Laptop.
Replies: 3
Views: 683

Re: Open Source H/W Laptop.

If there is ever a person to an open laptop from scratch then its him. As I have an interest in PIC micros then I found his article about hardware hacking the PICs security registers real interesting too. Anyone who can skim off the top of a chip case and look at the silicon etch pattern and instinc...
by Redrobes
Sun Dec 16, 2012 1:35 am
Forum: General discussion
Topic: Open Source H/W Laptop.
Replies: 3
Views: 683

Open Source H/W Laptop.

Bunnie Huang is building a laptop and every part of it including the PCB, hardware and drivers is going to be open source. This, like the RasPi is a big deal and he notes in the tech specs that, for fun, its got a "Raspberry-Pi compatible expansion header"... Read about it here: http://www.bunniest...
by Redrobes
Fri Dec 07, 2012 12:44 am
Forum: C/C++
Topic: Multithreading issue
Replies: 9
Views: 2636

Re: Multithreading issue

Try putting the -lpthread before the -o stuff. The linker processes the command line in order and at the point of the object file there has been no pthread declaration yet.
by Redrobes
Fri May 25, 2012 11:44 am
Forum: General discussion
Topic: Hardware 3D in a window demo
Replies: 36
Views: 16440

Re: Hardware 3D in a window demo

This is very cool and a great post. Probably the best post so far from outside of the RPi team. As I understand it, your using GLES as an off screen buffer and doing the read pixels and then using X to display it so its accelerated rendering but not accelerated display. Its a good temporary hack to ...
by Redrobes
Sat Apr 21, 2012 11:54 pm
Forum: General discussion
Topic: Would you like to know all about the BCM2835?
Replies: 18
Views: 3549

Re: Would you like to know all about the BCM2835?

Spotted...

"Driver development and experience with OpenCL"

...a future enhancement then to the PI then ?!

Not looking for telecommute work perchance ???
by Redrobes
Thu Apr 19, 2012 2:05 pm
Forum: Gaming
Topic: R-Pi Massively Multiplayer Online Role-Playing Games (MMORPG)
Replies: 309
Views: 80625

Re: R-Pi Massively Multiplayer Online Role-Playing Games (MMORPG)

<r>This seems like an interesting thread and similar to what I will be doing only mine is in 2D. Still, even with 2D you can zoom into maps and get connected as a client to a server hosting a map from which people can add/edit the maps and play RPG games.<br/> <br/> Its 2D because people can make an...
by Redrobes
Thu Apr 19, 2012 1:51 pm
Forum: Other projects
Topic: My Mapping App.
Replies: 3
Views: 1254

Re: My Mapping App.

Its been a while since I have posted but I wanted to say that even tho I have not yet got my grubby mitts on a board yet I have ported the Dice app to linux in a semi compatible way to how I think the Pi will interface to OpenGL. The port of the main app is continuing.
by Redrobes
Wed Mar 14, 2012 12:52 am
Forum: User groups and events
Topic: User group in Bristol
Replies: 33
Views: 6939

Re: User group in Bristol

<t>That's my neck of the woods too so I may be interested in a little bit of club time. I got up at 6am failed to get one on order so waiting for more units to go through before I get one. But id like to see one and measure it in real so I can start thinking about a box for it. I know dimensions are...
by Redrobes
Sat Mar 10, 2012 7:40 pm
Forum: General discussion
Topic: Closed source OpenGL demos
Replies: 3
Views: 1319

Re: Closed source OpenGL demos

<t>Hi Liz, was there any resolution to this. My intention is to write open gl closed source apps, some are free, some not, some will stay internal. From reading another post it looks like this file is an absolute requirement link file to initialize the video for GL with Broadcom bin blob enabled h/w...
by Redrobes
Mon Feb 20, 2012 1:55 am
Forum: Other projects
Topic: Use GPIO to control IR helicopter
Replies: 21
Views: 7741

Re: Use GPIO to control IR helicopter

<t>Gert said: <br/> <br/> <br/> Same experience here. I bought two for the kids. They were very, very difficult to control. Let me re-phrase that: We could not control them reliably enough to have any fun out of them.<br/> <br/> <br/> I'll just chip in here too. I bought one like it for a friends ki...
by Redrobes
Mon Feb 20, 2012 1:31 am
Forum: Other projects
Topic: Use GPIO to control IR helicopter
Replies: 21
Views: 7741

Re: Use GPIO to control IR helicopter

<t>I had a play with one of these RC helicopters the other day and I was surprised to note it was IR comms link.<br/> <br/> First of all you would need to decode the IR signal. Normally its modulated on a carrier which is often 38KHz and uses pulse position modulation. You can get 38KHz receiver mod...
by Redrobes
Sat Feb 04, 2012 2:15 am
Forum: General discussion
Topic: Perfect Case for everyone born in the 80's ;)
Replies: 37
Views: 14907

Re: Perfect Case for everyone born in the 80's ;)

Wouldn't it be so cool to have a RasPi in an old ZX81 case & authentic PSU ? You even get a keyboard with it...

Quake on a ZX81... LOL
by Redrobes
Sat Feb 04, 2012 2:00 am
Forum: Other projects
Topic: GPIOs suitable for Microswitches? Joysticks?
Replies: 14
Views: 4637

Re: GPIOs suitable for Microswitches? Joysticks?

<t>I made a MAME joystick console a lot like that in the image except I programmed up a PIC to do PS2 style keyboard IO to a PC. My mate tho just took an old USB keyboard apart and hacked the button wires directly onto the keys button pads and used its existing USB interface. His worked better and s...
by Redrobes
Thu Feb 02, 2012 3:08 pm
Forum: Other projects
Topic: Inertial navigation unit
Replies: 3
Views: 2761

Re: Inertial navigation unit

Sounds like a good application for it. I am planning on porting my mapping app which Id like to use in a car amongst other things so ill keep my eye on this.
by Redrobes
Thu Feb 02, 2012 3:02 pm
Forum: Other projects
Topic: Rugged case? Suticase And alternative cases?
Replies: 10
Views: 8026

Re: Rugged case? Suticase And alternative cases?

Since there is no moving parts and not much heat dissipation, you could pot it with a rubbery compound for a serious protection. Maybe resting a heat sink on the main cpu (or any other warm components (to be discovered)) whilst it sets (fins poking through) might be still worth it tho.
by Redrobes
Mon Jan 30, 2012 1:36 pm
Forum: Other projects
Topic: Astro photography
Replies: 27
Views: 15762

Re: Astro photography

<t>Isn't the normal method to use a quadrature photodiode and drive the tracking motors from the error off of the 4 photodiodes instead of using a full CCD. Whilst I agree that this does mean that you need the tracking star in the middle of the tracking scope, it does mean that you can continuously ...

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