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by experix
Mon Aug 31, 2015 3:41 pm
Forum: Off topic discussion
Topic: Questions for an English major.
Replies: 7
Views: 1597

Re: Questions for an English major.

With proportional spacing, a 'double space' becomes harder to define.
Beware of editing tools that think a lower-case sentence start is a mistake.
by experix
Tue Aug 25, 2015 2:50 pm
Forum: Troubleshooting
Topic: USB harddrive not working (not even enumerating)
Replies: 4
Views: 1032

Re: USB harddrive not working (not even enumerating)

Maybe that drive has gone crankish. Can you mount it on another computer?
by experix
Tue Aug 25, 2015 2:43 pm
Forum: General discussion
Topic: Detect lights On in my house
Replies: 4
Views: 795

Re: Detect lights On in my house

In many workplaces there are motion sensors which turn off the lights after some period of not detecting motion (an imperfect proxy for room not occupied). Maybe you could put an input on one of them (if it doesn't have that already) to get an override from the RPi if you still want to operate it re...
by experix
Tue Aug 18, 2015 2:08 pm
Forum: General discussion
Topic: Raspberry Pi 2 upgrade
Replies: 6
Views: 1332

Re: Raspberry Pi 2 upgrade

If you have things on the GPIO, be aware that the base address is different.
by experix
Mon Aug 17, 2015 4:49 pm
Forum: Other projects
Topic: GraphicsMaster tablet
Replies: 0
Views: 283

GraphicsMaster tablet

I have an old GraphicsMaster digitizing tablet (you push a mouse-like thing with a coil around the tablet surface and it sends position info to the computer via serial port). I seem to have reached a dead end trying to get info on its protocol. Has anybody encountered one of these?
by experix
Mon Aug 17, 2015 3:44 pm
Forum: Automation, sensing and robotics
Topic: PWM for servos, motors, and LEDs plus plus
Replies: 71
Views: 40857

Re: PWM for servos, motors, and LEDs plus plus

I'd leave the C program running all the time and let it read the buttons as well. I can't do that because I am constantly changing the C program. When I have it separated I let the bash script run at boot and with a button press it starts and stops the C program and when I change the C program I ca...
by experix
Mon Aug 17, 2015 3:29 pm
Forum: General programming discussion
Topic: Finding subsequences of a sequence
Replies: 8
Views: 1226

Re: Finding subsequences of a sequence

Getting into technical details, some info on the purpose and hardware would help in coming up with intelligent suggestions. If it is running on a general-purpose OS like Linux, you can set up a timer for each motor. Otherwise, maybe you have one timer that has to run all of the motors? The timer can...
by experix
Sat Aug 15, 2015 4:37 pm
Forum: General discussion
Topic: No picade case holes for cables? [Solved RTFM]
Replies: 13
Views: 1564

Re: No case holes for cables?

Studog, are you connecting the 120 VAC power to the GPIO? I'm sure this will make adequate holes in the case.
Heater, this seems to be one of the better titled posts. What more do you want?
by experix
Fri Aug 14, 2015 2:29 pm
Forum: Camera board
Topic: Instant false colour processing for Noir camera
Replies: 1
Views: 526

Re: Instant false colour processing for Noir camera

I don't know about elegant GPU solutions, but anyway you say a few seconds delay would be acceptable, and certainly this can be done in a few 1/100 of a second: Get an image in a bitmap format such as PPM so you can access individual pixels, and then simply translate the values as you like. I have s...
by experix
Thu Aug 13, 2015 9:11 pm
Forum: Camera board
Topic: Can one do serious work with this camera?
Replies: 4
Views: 1123

Can one do serious work with this camera?

I ran into many serious obstacles trying to use the RPi camera. Writeup for the MMAL library is hopeless, but somehow the v4l2 driver is based on MMAL (I think). But the v4l2 driver cannot give you a preview window with arbitrary location and size because it does not implement VIDIOC_CROPCAP, VIDIOC...
by experix
Tue Aug 11, 2015 3:05 pm
Forum: Other projects
Topic: Monitoring and promoting mouse romance
Replies: 4
Views: 789

Re: Monitoring and promoting mouse romance

Actually I don't know how to use RFID or whether it is suitable. The idea is to get a signal somehow whenever two mice are together, and the signal will tell you which mice are doing it. Probably the devices could be powered by ultracapacitors charged by an EM induction setup so the mice don't have ...
by experix
Tue Aug 11, 2015 2:41 pm
Forum: General discussion
Topic: Are there too many questions out of scope for this forum
Replies: 28
Views: 3373

Re: Are there too many questions out of scope for this forum

Many of the questions are about things people need to learn before they start trying to figure out how to use the RPi, and a lot of them repeat each other at least partially. Could it be helped with a sticky thread that directs people to texts, on-line instruction and so forth on shell syntax, funda...
by experix
Mon Aug 10, 2015 9:56 pm
Forum: Other projects
Topic: Monitoring and promoting mouse romance
Replies: 4
Views: 789

Re: Monitoring and promoting mouse romance

Here's an idea remotely inspired by FRET: equip the mice with little circuits that include RFID tags and proximity sensors, and make a receiver that tells you when one sensor is near another one.
by experix
Mon Aug 10, 2015 2:40 pm
Forum: Other projects
Topic: Floppy Drive Music
Replies: 14
Views: 13459

Re: Floppy Drive Music

Can you make music with a 500 MB hard disk drive from a VAX system? It has a **heavy** aluminum case measuring about 40 x 30 x 20 cm and inside there are very strong magnets, big platters and so on. Every detail seems to have been made in the most expensive way possible.
by experix
Thu Aug 06, 2015 2:30 pm
Forum: General discussion
Topic: PWM driven fan according to temperature
Replies: 30
Views: 3342

Re: PWM driven fan according to temperature

I got my Raspberry pi2 recently with heatsink,fan etc
Are you saying you got some sort of kit that includes the heatsink and fan? Who is selling that and why?
by experix
Thu Aug 06, 2015 2:24 pm
Forum: General discussion
Topic: Desautering and Adding
Replies: 5
Views: 698

Re: Desautering and Adding

I guess it's lead-free solder. Are techniques for that different from lead-tin? Can you use lead-tin on this board? Anyway, I probably would not do this at all since a USB adapter ought to be easy to get.
by experix
Tue Jul 28, 2015 8:25 pm
Forum: Camera board
Topic: Benefits of PI Camera?
Replies: 7
Views: 2178

Re: Benefits of PI Camera?

Thanks, 6by9, I'll try that tomorrow, since I feel like I'm getting the upper hand on a major lab cleanup that has been occupying my time.
by experix
Tue Jul 28, 2015 3:58 pm
Forum: Camera board
Topic: Benefits of PI Camera?
Replies: 7
Views: 2178

Re: Benefits of PI Camera?

From the postings about getting maximum stills per second, it doesn't appear to me that the RPi camera has any advantage over a USB webcam. I have demos using USB webcam with my data acquisition / display / analysis program, experix, operating it with v4l, in book/pictures and dist/source/xpx_local ...
by experix
Fri Jul 17, 2015 3:21 pm
Forum: Automation, sensing and robotics
Topic: Sensing a Laser Beam Hitting Object (Laser Range Finder)
Replies: 4
Views: 4595

Re: Sensing a Laser Beam Hitting Object (Laser Range Finder)

You might use a camera with a filter to admit only the laser wavelength, and scan the region of interest quickly during the camera's exposure time. But this has a lot of synchronization issues and probably will not give the best sensitivity. Probably a better approach is to scan with a modulated las...
by experix
Fri Jul 17, 2015 3:08 pm
Forum: C/C++
Topic: ARM UART driver
Replies: 2
Views: 1063

Re: ARM UART driver

I have a user-space UART driver that I made to replace /dev/ttyAMA0 in order to operate a gertbot faster than can be done going through the operating system (since it needs to do little input transactions interleaved with little output transactions, you can't just write or read a big file; hence man...
by experix
Thu Jul 16, 2015 2:33 pm
Forum: Off topic discussion
Topic: One of my favorite moderater quotes ever.
Replies: 2
Views: 540

Re: One of my favorite moderater quotes ever.

One of my favourite posts (which I have not been able to locate again) asked about ways to "sink time with the internet". Actually, I know of many ways to do that.
by experix
Thu Jul 16, 2015 2:16 pm
Forum: Advanced users
Topic: Accuracy time on RPi 2
Replies: 10
Views: 1284

Re: Accuracy time on RPi 2

If your program tells the ADC to convert, that's introducing a timing uncertainty. You can overcome that by triggering the ADC from a reliable accurate timer apart from the computer. Or do you need to trigger in response to an event? Then cause that event to trigger the ADC directly and also latch t...
by experix
Wed Jul 15, 2015 3:25 pm
Forum: C/C++
Topic: Individual Video Frame - Image Processing
Replies: 3
Views: 781

Re: Individual Video Frame - Image Processing

I have examples of capture/analyze/display cycles using a USB webcam and v4l2. This is in the latest uploads to http://experix.sourceforge.net. The relevant files are book/picture, dist/source/xpx_local/webcam.hlp and dist/source/xpx_local/webcam.c.
by experix
Tue Jul 14, 2015 2:46 pm
Forum: Other projects
Topic: 360 Photo
Replies: 3
Views: 697

Re: 360 Photo

There's an adapter for I-phones and such that puts a cylindrically symmetric curved reflector coaxial with the camera. That way the camera, pointed up, gets a scrambled 360-degree panorama that needs to be processed through a complicated transform to look normal.
by experix
Tue Jul 14, 2015 2:30 pm
Forum: Automation, sensing and robotics
Topic: Assistance with small soldering job
Replies: 5
Views: 880

Re: Assistance with small soldering job

Soldering is not so hard (unless you have disabilities that interfere). You seem to be assuming that this one little job will be all the soldering you need to get done in your career-- I find that unlikely. You are likely to encounter a lot less less aggravation and expense if you can do it yourself...

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