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by experix
Thu Feb 12, 2015 3:29 pm
Forum: Other projects
Topic: SPACE
Replies: 9
Views: 1155

Re: SPACE

I know that space probes use electronic parts that have tougher specs for radiation vulnerability. How is the pi in this regard? Is it an issue near earth (within the Van Allen belts)? How about farther out?
by experix
Wed Feb 11, 2015 9:44 pm
Forum: HATs and other add-ons
Topic: experix release with gertbot demo
Replies: 0
Views: 836

experix release with gertbot demo

I have posted an update to experix version r14 (look in the files section at experix.sourceforge.net). It features a new command called 'gpio' which performs operations on the GPIO of the Raspberry Pi. There are two demos. The one for the gertbot (dist/source/xpx_local/gpioRPi_demos/gertbot.xpx) sho...
by experix
Mon Feb 09, 2015 3:25 pm
Forum: General discussion
Topic: purging memory
Replies: 11
Views: 1136

Re: purging memory

If you know that a certain program is leaking, then you can close it and all the memory it is holding gets returned to the system. If it's a buggy library I'm not so sure. Maybe you have to close everything that uses the library so that it gets unloaded. If it's a buggy daemon I suppose you need to ...
by experix
Fri Feb 06, 2015 4:01 pm
Forum: Automation, sensing and robotics
Topic: convert Hz to mA
Replies: 6
Views: 2307

Re: convert Hz to mA

I had a brief look in the peripherals guide but didn't find a counter with input from the GPIO. But somebody who knows how to read that document properly might find it. It seems like an obvious thing to include. Anyway, lacking that, you can connect your load sensor to a counter that can be accessed...
by experix
Thu Feb 05, 2015 5:05 pm
Forum: Advanced users
Topic: userland serial port
Replies: 0
Views: 263

userland serial port

I made a linear motor for a biophysical experiment and want to control it via a PWM output from a gertbot. By writing PWM setting commands one at a time to /dev/ttyAMA0 I can do 50 per second. Not fast enough! If I stuff all those commands into a buffer and write that, I can do about 1000 per second...
by experix
Wed Feb 04, 2015 3:12 pm
Forum: General discussion
Topic: What Windows 10 'IoT' could mean for Raspberry Pi 2
Replies: 48
Views: 7400

Re: What Windows 10 'IoT' could mean for Raspberry Pi 2

Without "slagging off" anybody (delightful British idiom, I guess? I had not heard it before) I want to put in a plug for free, open-source software. That is "free as in freedom", not as in "free beer". I worked for a long time with memory-extended DOS, and when that was completely obsolete I tried ...
by experix
Fri Jan 30, 2015 6:57 pm
Forum: C/C++
Topic: How do I learn C
Replies: 33
Views: 4975

Re: How do I learn C

When you have a little competence with the C language, the best way I know about to get proficient at that and learn the GNU-Linux system at the same time is by working through The Linux Programming Interface by Michael Kerrisk ( http://man7.org/tlpi) . Its lucid prose is a real pleasure to read, an...
by experix
Mon Jan 26, 2015 8:01 pm
Forum: HATs and other add-ons
Topic: gertbot request for enhancements
Replies: 16
Views: 7729

Re: gertbot request for enhancements

You can then switch to 115Kbaud giving you more then enough bandwidth to transport two twelve-bit ADC's values every millisecond. This requires user to reprogram the gertbot. Maybe it would be worthwhile to give it a 'baud-change' command (no board re-design needed for that apparently), or jumpers ...
by experix
Thu Jan 22, 2015 4:36 pm
Forum: C/C++
Topic: Understanding system()
Replies: 5
Views: 965

Re: Understanding system()

You do not necessarily need root privilege to use GPIO; it depends on the method. If you use the kernel interfaces like /sys/class/gpio/*, /dev/spidev*, and /dev/i2c*, you only need user or group memberships sufficient for the discretionary access controls that you have applied to the device files....
by experix
Tue Jan 20, 2015 9:15 pm
Forum: HATs and other add-ons
Topic: gertbot request for enhancements
Replies: 16
Views: 7729

Re: gertbot request for enhancements

You will not be able to sample thousands of points every ms. You will be able to sample thousands of points in just a bit over (number of points)*1ms assuming you add enough multiplexers / ADC channels Sorry, I should have been more clear. I want to sample from 1 or 2 ADCs, getting thousands of sam...
by experix
Tue Jan 20, 2015 5:39 pm
Forum: HATs and other add-ons
Topic: gertbot request for enhancements
Replies: 16
Views: 7729

Re: gertbot request for enhancements

[I will see what is possible as this seems a very specific application which would benefit more from running the whole algorithm on the board. Beware that the ADC are not very fast (about 1 millisecond per sample) and that the DACs have only limited range. I need to do some experimenting with a thr...
by experix
Tue Jan 20, 2015 4:58 pm
Forum: General discussion
Topic: How to modify the behaviour of the "halt" command
Replies: 5
Views: 939

Re: How to modify the behaviour of the "halt" command

Nothing I got with my RPi kit said anything about 'halt', and I have been using 'shutdown -h now' as I do on my other systems. Is there any difference?
by experix
Mon Jan 19, 2015 10:06 pm
Forum: HATs and other add-ons
Topic: gertbot request for enhancements
Replies: 16
Views: 7729

gertbot request for enhancements

(gert asked me to put this on the forum; this seems to be the best place) Some automation would help the gertbot, particularly when the programmer wants to do things rapidly with exact timing. I don't know what resources it has, particularly memory, so here goes: I want to send it an array of DAC va...
by experix
Wed Jan 14, 2015 9:43 pm
Forum: General discussion
Topic: Experiments with Raspberry + FPGA/CPLD
Replies: 57
Views: 9156

Re: What can I do with my FPGA/CPLD Raspberry hardware

I don't know about the windows software. I picked Xilinx from a few FPGA companies because they offered GNU-Linux software, and that is what I used. It's been so long since I set all this up that I can't remember the details now, but if it will help I'll turn on the computer where I have that and at...
by experix
Tue Jan 13, 2015 8:13 pm
Forum: General discussion
Topic: Experiments with Raspberry + FPGA/CPLD
Replies: 57
Views: 9156

Re: What can I do with my FPGA/CPLD Raspberry hardware

Thank you, I would appreciate if you send me files. I would really like to keep this project no-GUI. I like to work with terminals but I am surrounded by windows machines and GUI's everywhere now. I have reviewed my files (it's work done some years back and semi-abandoned). The stuff I think may be...
by experix
Mon Jan 12, 2015 4:00 pm
Forum: General discussion
Topic: Experiments with Raspberry + FPGA/CPLD
Replies: 57
Views: 9156

Re: What can I do with my FPGA/CPLD Raspberry hardware

This is interesting. I used a Coolrunner to drive a laser modulator for an experiment that needed 2-color pulse width control synchronized with photon counting. I used experix to control the CPLD via a parallel port interface from my PC. The GUI from Xilinx was a huge pain in the ass so I figured ou...
by experix
Mon Dec 22, 2014 4:04 pm
Forum: General discussion
Topic: ext2/etx4
Replies: 7
Views: 1839

Re: ext2/etx4

[quote="totoharibo"][quote="Heater"

I don't use it for security of course.

what is 'it'-- ext2, ext4 or something else? And please say something about this security issue.
by experix
Mon Dec 15, 2014 3:59 pm
Forum: C/C++
Topic: image processing
Replies: 1
Views: 608

Re: image processing

You don't say what the motivation is, or what kind of processing you want to do. I have a demo that I ran on the RPi model B with a USB webcam, making and displaying 640x480 pixel images. It could almost do 3 per second. If you add in some fancy Fourier transform manipulation, that will slow it down...
by experix
Tue Dec 09, 2014 3:47 pm
Forum: Automation, sensing and robotics
Topic: DAQ software
Replies: 8
Views: 1370

Re: DAQ software

It looks easy. For such a relatively slow rate of data acquisition, you could use the gpio command that comes with the wiringPi libraries to obtain each data point (I only recommend this as a way to get started in case I don't get my experix-gpio interface done quick enough). In an experix script yo...
by experix
Mon Dec 08, 2014 4:05 pm
Forum: Automation, sensing and robotics
Topic: DAQ software
Replies: 8
Views: 1370

Re: DAQ software

Maybe you want to have a look at experix.sourceforge.net. This is a command-line driven program running in a terminal (i.e. not X-windows), using framebuffer graphics and a scripting language that lets you do anything-- such as start a thread that gathers, displays and archives data as directed by t...
by experix
Tue Dec 02, 2014 5:31 pm
Forum: HATs and other add-ons
Topic: 12-bit ADC on gertboard?
Replies: 1
Views: 1444

12-bit ADC on gertboard?

The MCP3202 12-bit ADC has the same pinout as the MCP3002 10-bit ADC that is used on the gertboard. Can I substitute it? Are there other or better ways to increase the resolution and get at least 10 KHz sampling rate?
by experix
Fri Nov 28, 2014 7:05 pm
Forum: General discussion
Topic: Cheap camera not usb how to
Replies: 5
Views: 862

Re: Cheap camera not usb how to

Is speed an issue? I don't have an RPi camera, so maybe somebody can help with figures for that. Here's what I found using a Logitech C270 operated by libv4l2 (see book/pictures and dist/source/xpx_local/webcam.c from experix.sourceforge.net). Doing a tight loop that makes and displays 100 640x480 p...
by experix
Thu Nov 27, 2014 5:28 pm
Forum: C/C++
Topic: Reading Cycle Counter from C
Replies: 6
Views: 4422

Re: Reading Cycle Counter from C

Considering user-kernel transitions and scheduling issues, can ccnt used in this manner give time values with any more accuracy and resolution than gettimeofday()? Maybe you will need to code the ccnt accesses directly in your program and run it as root.
by experix
Wed Nov 26, 2014 10:31 pm
Forum: Bare metal, Assembly language
Topic: Introducing USPi - A bare metal USB driver written in C
Replies: 73
Views: 21239

Re: Introducing USPi - A bare metal USB driver written in C

Is it specialized for RPi, or more generally useful?
Is it optimized for RPi, making it a better choice than libusbx or something else?
Does it provide basic transfer operations like libusbx does, or is is more high-level?
by experix
Wed Nov 26, 2014 10:14 pm
Forum: General discussion
Topic: Picking a Language
Replies: 31
Views: 3373

Re: Picking a Language

I don't understand the question, but the answer is obviously 42.

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