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by jbeale
Fri Jun 22, 2018 6:31 pm
Forum: Automation, sensing and robotics
Topic: Raspi-powered seismometer/seismograph
Replies: 61
Views: 32447

Re: Raspi-powered seismometer/seismograph

The Mindsets Lego Seismometer looks like a neat widget. I see on the webpage https://mindsetsonline.co.uk/shop/lego-seismometer-kit/ they mention "1-2 Hz" and it seems less expensive than a 5 Hz vertical geophone. In fact it seems to be, in effect a 1-2 Hz vertical geophone. I wonder if it has publi...
by jbeale
Thu Jun 21, 2018 3:53 pm
Forum: Automation, sensing and robotics
Topic: Cheap USB temperature sensors
Replies: 5
Views: 192

Re: Cheap USB temperature sensors

This is the part I'm talking about. There is a long lead containing the actual sensor. I stuck the sensor end to piece of metal lying on the table (separate from the R-Pi) so the temperature changes pretty slowly, and independently of the USB socket. https://www.ebay.com/itm/Digital-USB-DS18B20-1wir...
by jbeale
Thu Jun 21, 2018 2:24 pm
Forum: Automation, sensing and robotics
Topic: Cheap USB temperature sensors
Replies: 5
Views: 192

Re: Cheap USB temperature sensors

Previously had to be logged into my own google account to see, but I fixed the image link, I think.
by jbeale
Thu Jun 21, 2018 3:05 am
Forum: Automation, sensing and robotics
Topic: Cheap USB temperature sensors
Replies: 5
Views: 192

Cheap USB temperature sensors

I needed to read ambient temperature to do some temperature corrrection for a sensor. Rather than deal with a lower-level interface directly I thought the easiest thing would be to get a USB sensor. I found two of them, one called "TEMPer" on Amazon and another one called "Digital USB DS18B20" sold ...
by jbeale
Thu May 31, 2018 5:10 am
Forum: Beginners
Topic: Raspberry lifetime
Replies: 23
Views: 939

Re: Raspberry lifetime

Depending on how you use it, it is possible to wear out the SD memory card or USB memory stick if you continually write and erase lots of data (eg. use as video security camera storing video locally.) I have managed to do that. But those memory cards can be replaced. I also have a pi in a data cente...
by jbeale
Wed May 16, 2018 7:08 pm
Forum: Staffroom, classroom and projects
Topic: general intro to circuits- 4th grade
Replies: 0
Views: 382

general intro to circuits- 4th grade

I am not a teacher, but my daughter's 4th grade class invited me to come in and present something on "circuits" to start their unit on that subject. I brought my small oscilloscope to the class and put it on the table facing straight up, underneath their document camera, which projected a live view ...
by jbeale
Thu May 10, 2018 6:17 pm
Forum: Camera board
Topic: milliseconds in raspistill filename
Replies: 14
Views: 1704

Re: milliseconds in raspistill filename

I think NTP could get you within single-digit msec on a wired LAN, but getting below 1 msec on a consistent basis may require deeper understanding of several different things; details of your network adaptors and everything running on your hardware on both ends. Not necessarily impossible, but I thi...
by jbeale
Mon May 07, 2018 10:54 pm
Forum: Off topic discussion
Topic: non-Pi question... where are those CPU cycles going?
Replies: 1
Views: 1578

non-Pi question... where are those CPU cycles going?

I know this is off topic on the RPi board, but I'm not a member of any group where it would be on-topic, so I'm just throwing it out there... My Windows PC at work is always running "scan64.exe" (VirusScan On-Demand Scanner) and "mcshield.exe" (McAfee On-Access Scanner Service) and using roughly 25%...
by jbeale
Tue Apr 24, 2018 12:16 am
Forum: C/C++
Topic: very simple serial port example?
Replies: 5
Views: 559

Re: very simple serial port example?

Thank you for the WiringPi suggestion! This is the simple C example I was looking for: https://github.com/WiringPi/WiringPi/bl ... rialRead.c
by jbeale
Sun Apr 22, 2018 5:16 pm
Forum: C/C++
Topic: very simple serial port example?
Replies: 5
Views: 559

very simple serial port example?

If I want to read 4 bytes from the serial port in Python, it takes three lines, for example: import serial ser = serial.Serial('/dev/ttyUSB0',115200) inWord = ser.read(4) If I want to do the same thing in C, what I have found takes more than a full page of code setting up the serial port. Here is on...
by jbeale
Fri Apr 20, 2018 6:04 pm
Forum: Python
Topic: writing I32 to binary file: endian-ness on R-Pi
Replies: 12
Views: 566

Re: writing I32 to binary file: endian-ness on R-Pi

While I can't disagree with using Audacity as a large ADC data set viewer, once you get your import parameters sorted it I find it much quicker to use SoX (in the standard Raspbian repos: sudo apt install sox libsox-fmt-all ) to do the conversion. As it works from the command line, you can ferret t...
by jbeale
Fri Apr 20, 2018 4:29 pm
Forum: General discussion
Topic: finding older model RPi on the used market
Replies: 6
Views: 485

finding older model RPi on the used market

In another forum someone was asking how to make a sensor network more cheaply, with reference to the "Raspberry Shake" and "Raspberry Boom" devices, which use an R-Pi as controller plus add-on board with 24-bit 100 Hz ADC. The computing power needed for this use is low, so any of the versions of R-P...
by jbeale
Thu Apr 19, 2018 9:23 pm
Forum: Automation, sensing and robotics
Topic: Raspi-powered seismometer/seismograph
Replies: 61
Views: 32447

software for seismic monitoring and analysis

There is some software for this available called "ObsPy" for Seismic Observatory in Python: https://docs.obspy.org/tutorial/index.html and it has many different functions and capabilities. Here is a page describing various "triggers" available to detect quakes in the presence of noise, both from fea...
by jbeale
Tue Apr 17, 2018 10:37 pm
Forum: Automation, sensing and robotics
Topic: Raspi-powered seismometer/seismograph
Replies: 61
Views: 32447

Re: Raspi-powered seismometer/seismograph

I don't personally know of such software, but most of the quakes I've seen have a characteristic spectrogram profile that is unlike most ambient noise from traffic, etc. There is a sudden start followed by an exponential decay over 10s of seconds or more, and at any moment in time the larger signal ...
by jbeale
Mon Apr 16, 2018 1:57 pm
Forum: Python
Topic: writing I32 to binary file: endian-ness on R-Pi
Replies: 12
Views: 566

Re: writing I32 to binary file: endian-ness on R-Pi

Audacity can import I32, but the project edit and display mode is reported as 32-bit float. If it is representing numbers as 32-bit floats internally, that means 1 bit sign, 8 bits exponent and 23 bits mantissa. So it seemed to me (late last night when my brain wasn't so great) that the low-order 9 ...
by jbeale
Mon Apr 16, 2018 6:44 am
Forum: Python
Topic: writing I32 to binary file: endian-ness on R-Pi
Replies: 12
Views: 566

writing I32 to binary file: endian-ness on R-Pi

I have an ADC sending 24-bit samples that I want to record and later examine using Audacity. To avoid having to create a WAV or other standard format file, I'm just writing raw I32 values and using the Audacity "raw input" option, File -> Import -> Raw Data -> Encoding: "Signed 32-bit PCM". I didn't...
by jbeale
Thu Apr 05, 2018 7:33 pm
Forum: Off topic discussion
Topic: Longest Raspberry Pi uptime
Replies: 58
Views: 33115

Re: Longest Raspberry Pi uptime

Is it a new high score? 0 users as this was an automated script that sends an email.
Load near 1 as it has been running a distributed computing "BOINC" client (for a loong time).

05-APRIL-2018
11:57:01 up 1600 days, 18:47, 0 users, load average: 1.01, 1.06, 1.11
by jbeale
Sun Mar 25, 2018 5:46 am
Forum: For sale
Topic: Personal seismograph Raspberry Shake
Replies: 3
Views: 3342

Re: Personal seismograph Raspberry Shake

Addendum: after a bit more research, I've come to the conclusion that an instrument like the "Raspberry Boom" which is detecting only sound below 40 Hz, is good for sensing events that move large volumes of air: meteors, volcanic eruptions, large-scale explosions, ocean surf, and of course wind. It ...
by jbeale
Thu Mar 22, 2018 10:29 pm
Forum: For sale
Topic: Personal seismograph Raspberry Shake
Replies: 3
Views: 3342

Raspberry Shake -update March 2018

After a year and a few months, my Raspberry Shake is continuing to operate well in my garage, sending a constant stream of seismic data to the online server. I have to say I have been impressed by the stability of this device. It has captured quite a few earthquakes (I'm in California) and has had n...
by jbeale
Wed Mar 21, 2018 5:30 pm
Forum: General discussion
Topic: New Raspberry Pi model 3B+ 1.4 GHz, 330Mbit Ethernet, 802.11ac, PoE
Replies: 376
Views: 32675

Re: New Raspberry Pi model 3B+ 1.4 GHz, 330Mbit Ethernet, 802.11ac, PoE

The boot sequence documentation should answer that question. As I recall, after it checks for an SD card, it will keep checking USB devices until it finds a bootable device...or--of course--fail if there isn't one. Is this the documentation you're talking about? I don't see any mention of multiple ...
by jbeale
Wed Mar 21, 2018 2:17 pm
Forum: General discussion
Topic: New Raspberry Pi model 3B+ 1.4 GHz, 330Mbit Ethernet, 802.11ac, PoE
Replies: 376
Views: 32675

Re: New Raspberry Pi model 3B+ 1.4 GHz, 330Mbit Ethernet, 802.11ac, PoE

Very happy to hear USB boot is working well. Is there any provision for handling the case of more than one USB device connected at once, or does it fail if the first enumerated USB mass-storage device is not bootable?
by jbeale
Wed Mar 21, 2018 4:01 am
Forum: General discussion
Topic: New Raspberry Pi model 3B+ 1.4 GHz, 330Mbit Ethernet, 802.11ac, PoE
Replies: 376
Views: 32675

Re: New Raspberry Pi model 3B+ 1.4 GHz, 330Mbit Ethernet, 802.11ac, PoE

Just got my 3B+ in the mail. It came a lot faster after the order than the original Pi 1B did, back in 2012 :-).
Question: I guess it's "no-clean" and doesn't affect operation, but should there be this much flux residue on the backside?
Photo: https://photos.app.goo.gl/3FuGlU2RV1Soa26k2
by jbeale
Thu Mar 15, 2018 4:05 am
Forum: General discussion
Topic: New Raspberry Pi model 3B+ 1.4 GHz, 330Mbit Ethernet, 802.11ac, PoE
Replies: 376
Views: 32675

Re: New Raspberry Pi model 3B+ 1.4 GHz, 330Mbit Ethernet, 802.11ac, PoE

I don't see any indication that 5V chip you mention is connected to the on-board USB ports. It might be for some other onboard device or port? On the other hand, what is the maximum current spec of that micro-USB power input to the R-Pi? If you subtract off the current drawn by the 3B+ itself at max...
by jbeale
Sun Mar 04, 2018 8:13 pm
Forum: Troubleshooting
Topic: How to make sure the rpi cpu is not throttled down?
Replies: 3
Views: 2626

Re: How to make sure the rpi cpu is not throttled down?

http://math-atlas.sourceforge.net/atlas_install/node5.html If ATLAS's configure detects that CPU throttling is enabled, it will kill itself. The reason is that ATLAS depends on timings to tune the library to your machine. OS-controlled throttling is so course-grained that essentially all timings be...
by jbeale
Fri Mar 02, 2018 5:31 am
Forum: Troubleshooting
Topic: [SOLVED] 3TB NTFS hard drive not supported?
Replies: 0
Views: 199

[SOLVED] 3TB NTFS hard drive not supported?

UPDATE: Solved. Working fine after doing the magic incantation of: sudo apt-get install ntfs-3g Problem: I did not realize that the RPi-3 with current Raspbian does not support larger USB hard drives such as 3 TB with NTFS. Is there any workaround for this? I already have a lot of data on it, so I'...

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