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by experix
Tue Jul 14, 2015 2:11 pm
Forum: C/C++
Topic: Recommended reading for MMAL
Replies: 30
Views: 4159

Re: Recommended reading for MMAL

Is there a guide somewhere that will tell us what questions we should ask?
by experix
Tue Jul 14, 2015 2:07 pm
Forum: General discussion
Topic: Raspberry Native C and Speed Tests
Replies: 10
Views: 3031

Re: Raspberry Native C and Speed Tests

What are people saying when they attach 'native' to 'C'? Are they doing this to clarify that they are not talking about 'non-native' C?
by experix
Fri Jul 10, 2015 7:08 pm
Forum: General discussion
Topic: Image compression - shrink the size
Replies: 8
Views: 1290

Re: Image compression - shrink the size

Do you mean 4 bits of information for each color in each pixel? It is trivial to reprocess a BMP format picture having 1 or 2 bytes per pixel into such a form-- just take each color triple, extract the 4 most significant bits of each color and then pack it any way you like. I don't know if there's a...
by experix
Fri Jul 10, 2015 3:58 pm
Forum: General discussion
Topic: Image compression - shrink the size
Replies: 8
Views: 1290

Re: Image compression - shrink the size

If you want to shrink it to a specific size (number of pixels in X and Y), you do this: Convert to BMP format, which consists of a small header giving the dimension information and then a long list of pixel values. That is for each pixel in the nX by nY image, 3 numbers: intensity in each of the pri...
by experix
Thu Jul 09, 2015 2:07 pm
Forum: C/C++
Topic: Recommended reading for MMAL
Replies: 30
Views: 4159

Re: Recommended reading for MMAL

The MMAL documentation doesn't really attempt to explain what the library does and how it works. What's needed is a functional description of the processor systems that it handles, what those do and how the library exposes its capabilities to the user.
by experix
Wed Jul 08, 2015 2:30 pm
Forum: General discussion
Topic: How to connect a stepper motor
Replies: 9
Views: 973

Re: How to connect a stepper motor

Normally people on this forum jump at the chance to help somebody do something. I think for some strange reason they were put off by the string of question marks. Anyway, what the stepper motor needs is called an 'H bridge', or really two of them (for a typical stepper motor). You can get these as s...
by experix
Tue Jul 07, 2015 3:18 pm
Forum: Advanced users
Topic: 360 degree camera
Replies: 6
Views: 3296

Re: 360 degree camera

How about reciprocating motion rather than continuous rotation?
by experix
Tue Jul 07, 2015 3:14 pm
Forum: General discussion
Topic: Popular open source projects
Replies: 3
Views: 532

Re: Popular open source projects

These are things I needed that were not on the noobs card: sudo apt-get install the following: gpm Essential for anybody doing serious work. Saves a tremendous lot of typing. tree Very handy time-saving utility for doing directory searches and so on. hexedit for when you need to look at binary data ...
by experix
Mon Jul 06, 2015 2:33 pm
Forum: General discussion
Topic: Does your project need an automated RPi installation image?
Replies: 5
Views: 830

Re: Does your project need an automated RPi installation ima

By automated installation image do you mean something that somebody can download that will automatically install a piece of software plus a few libraries and utilities that it needs, and make a few changes in /etc files and so on? I can give you detailed instructions for installing experix, starting...
by experix
Mon Jul 06, 2015 2:19 pm
Forum: General discussion
Topic: Popular open source projects
Replies: 3
Views: 532

Re: Popular open source projects

check out http://experix.sourceforge.net
25 year old project recently adapted to RPi
scripting system for device control, data acquisition, presentation and analysis
by experix
Fri Jul 03, 2015 3:31 pm
Forum: Camera board
Topic: theory: best spot size to locate centroid?
Replies: 2
Views: 467

Re: theory: best spot size to locate centroid?

Try looking in the field of super-resolution microscopy. The assumption for a very long time was that you could never get resolution better then 1/2 the wavelength, due to diffraction. But if you are trying to locate a few very small bright objects, such as fluorescent molecules, you can do a lot be...
by experix
Wed Jul 01, 2015 3:15 pm
Forum: General discussion
Topic: more efficient forum browsing
Replies: 7
Views: 917

more efficient forum browsing

How about a next topic in this list button, so I don't have to push the return to X button and then look down the list to find the next post?
by experix
Wed Jun 24, 2015 7:25 pm
Forum: General discussion
Topic: USB socket robustness
Replies: 4
Views: 570

USB socket robustness

The RPi, like all computers I have seen, has USB connectors so close together that two devices (in this case the keyboard plug and a pretty average sort of memory stick) cannot go side-by-side, and when they are one above the other they crowd each other so that neither is completely straight-on. Whe...
by experix
Tue Jun 23, 2015 3:32 pm
Forum: C/C++
Topic: Using mmal_core
Replies: 1
Views: 706

Re: Using mmal_core

Maybe the linker hasn't been told to look in /opt/vc/lib. Try adding "-L /opt/vc/lib" to the linking command. I found that was necessary when I build RaspiStill from sources.
by experix
Mon Jun 22, 2015 7:46 pm
Forum: Camera board
Topic: mmal and vcos api
Replies: 1
Views: 1169

mmal and vcos api

I got the raspicam sources from github and compiled it all into a working raspistill program (it only needed a few adjustments to find headers). This is the first step to making my own camera operating code to put in my programs. It would help me a lot if I could find the documentation for the mmal ...
by experix
Wed Jun 17, 2015 2:34 pm
Forum: C/C++
Topic: printf not printing doubles (solved!)
Replies: 14
Views: 6237

Re: printf not printing doubles

printf problems often turn out to be the wrong specifier used with a variable. I can't tell from what you posted because you don't include the declarations.
by experix
Thu Jun 11, 2015 2:50 pm
Forum: General discussion
Topic: Rasbiam ARMv7 optimization
Replies: 21
Views: 3488

Re: Rasbiam ARMv7 optimization

That is obviously the right question, but I thought the OP was puzzled because he could not get to 100% CPU utilization as reported by the proc interface.
by experix
Thu Jun 11, 2015 2:41 pm
Forum: C/C++
Topic: mutex
Replies: 4
Views: 1089

Re: mutex

If I understand your question, it is a common issue-- to prevent multiple instances of a given program from running at the same time. The usual way to address this is to write code near the start of the main function, do do this: look for a certain file with a very specific name, like /tmp/glork_is_...
by experix
Mon Jun 08, 2015 2:26 pm
Forum: Advanced users
Topic: Arm Forth Project
Replies: 29
Views: 8654

Re: Arm Forth Project

When I try to download your file I get 'not found'.
www.isforth.com is a page of Chinese (I think).
I am interested in trying your Forth and making comparisons vs. experix.
by experix
Mon Jun 08, 2015 2:14 pm
Forum: General discussion
Topic: Rasbiam ARMv7 optimization
Replies: 21
Views: 3488

Re: Rasbiam ARMv7 optimization

I have not yet purchased a model 2. When I do I'll try this: Make a small program (in C) that runs a tight little code loop with NO i/o of any sort. Run an instance of that and look at CPU usage (using the top command). Run another instance and look again. And so on, until it maxes out. Comments ple...
by experix
Sun Jun 07, 2015 12:54 am
Forum: HATs and other add-ons
Topic: gertbot newbe problems
Replies: 2
Views: 1497

Re: gertbot newbe problems

When you say the controller does not work below 8 v. I think clarification is in order. The gertbot operates and responds to commands when mounted on the RPi with no other connections. I guess you mean the H bridges are not designed to operate below 8 v. external supply. An easy thing to use for tes...
by experix
Sat Jun 06, 2015 3:58 pm
Forum: General discussion
Topic: offering raspbian SD with experix
Replies: 0
Views: 276

offering raspbian SD with experix

Over the past 25 years I have been developing a system for laboratory instrument control, data collection, display and analysis called experix . It is licensed under GPL and made available at http://experix.sourceforge.net . It runs on GNU-Linux PCs and Raspberry Pis and probably any 32-bit little-e...
by experix
Thu Jun 04, 2015 3:56 pm
Forum: General discussion
Topic: forum help
Replies: 2
Views: 545

forum help

I wrote a long post with nano, and want to put it on the forum. I can pick up pieces of it with the mouse and drop them in the window for post-composing, but that's clumsy, plus each line as shown in the text editor window comes over with a linefeed and I would like to let the forum decide where to ...
by experix
Sat May 23, 2015 6:59 pm
Forum: General discussion
Topic: ok to distribute SD copies?
Replies: 1
Views: 370

ok to distribute SD copies?

I want to make copies of my SD and send them to people interested in trying experix (platform for experiment control and data acquisition, http://experix.sourceforge.net ). Maybe also put the image where they can download it. Does this violate any copyrights or foundation rules or guidelines? I'm ta...
by experix
Thu May 21, 2015 8:09 pm
Forum: General discussion
Topic: Annoyed
Replies: 7
Views: 1067

Annoyed

I logged in and wrote a long post. I was interrupted a few times so some time passed. Eventually I got it done and pushed the 'preview' button. It says I need to log in! And what I wrote is nowhere to be found!
:evil:

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