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by jbeale
Fri Aug 24, 2018 9:12 pm
Forum: Troubleshooting
Topic: RPi Zero USB OTG (usb-ethernet device)
Replies: 0
Views: 84

RPi Zero USB OTG (usb-ethernet device)

I'm trying to use my Raspberry Pi Zero V1.2 with current Raspbian Lite: Linux rp01 4.14.50+ #1122 Tue Jun 19 12:21:21 BST 2018 armv6l GNU/Linux in the USB OTG ("usb gadget") mode, to appear as a USB-Ethernet device to another PC (in this case, a MiniPC running Ubuntu 18.04.1). Following an online tu...
by jbeale
Mon Aug 20, 2018 6:43 pm
Forum: Beginners
Topic: measure height elevation
Replies: 5
Views: 161

Re: measure height elevation

There are pressure sensors that do have a few cm height resolution, for example, Honeywell makes this differential pressure sensor: https://www.digikey.com/product-detail/en/honeywell-sensing-and-productivity-solutions/HSCMRRD2.5MDSA3/HSCMRRD2.5MDSA3-ND/3935154 its claimed *accuracy* is 0.25% full s...
by jbeale
Mon Aug 20, 2018 4:07 pm
Forum: General discussion
Topic: surprising result after applying +12V to +5Vin
Replies: 5
Views: 449

Re: surprising result after applying +12V to +5Vin

That's a neat story (at least the first part). Seems like your Pi had a real mechanical circuit breaker!
Yes, my downfall was soldering on the same kind of generic 5.5/2.1 mm DC power jack as I use for +12V, and then being in a hurry and careless about connections.
by jbeale
Mon Aug 20, 2018 4:20 am
Forum: General discussion
Topic: surprising result after applying +12V to +5Vin
Replies: 5
Views: 449

Re: surprising result after applying +12V to +5Vin

I was not speaking of the onboard audio output, but a third-party external USB-audio adapter which I was using for a mic input. Quite a flimsy and cheap one too, I think it was under $5 from ebay. The USB port provides +5V output, so I did not expect it to be much different than the board's own +5V ...
by jbeale
Mon Aug 20, 2018 2:05 am
Forum: General discussion
Topic: surprising result after applying +12V to +5Vin
Replies: 5
Views: 449

surprising result after applying +12V to +5Vin

I did a dumb thing today to a RPi 3B, applying +12V directly from a 14 Ah battery to the +5V / GND GPIO pins (and in fact it was through a good soldered connection, not just spring contact wires). Unsurprisingly there was small jet of flame from the PCB, as this battery can probably deliver 50 A in ...
by jbeale
Wed Aug 15, 2018 4:34 am
Forum: Networking and servers
Topic: USB networking for secure file sharing
Replies: 11
Views: 335

Re: USB networking for secure file sharing

In case you were puzzled why anyone would want this, the use case is a Windows PC that has a tested software system and changing any of the application software is difficult. However purely windows-OS-level changes such as permissions on a shared folder (and installing the Ethernet-over-USB driver) ...
by jbeale
Mon Aug 13, 2018 4:42 pm
Forum: Networking and servers
Topic: USB networking for secure file sharing
Replies: 11
Views: 335

USB networking for secure file sharing

I know it is possible to read a shared folder on a Windows PC from a remote Pi over the network using SAMBA. I understand the RPi Model A+ and also the Zero and Zero+W can work in "USB Gadget" mode (eg. USB device, not host). Also that there exist drivers to make it possible to do TCP/IP over USB as...
by jbeale
Fri Aug 10, 2018 6:05 pm
Forum: Troubleshooting
Topic: software shutdown and LED blinking
Replies: 2
Views: 65

Re: software shutdown and LED blinking

"As soon as the ten winks are done you can safely pull the power."

Ok. It sounds like I should wait for it to be completely done blinking then.
Apparently I've just been lucky all those times before that I didn't wait, and did not have SD card damage?
by jbeale
Fri Aug 10, 2018 5:41 pm
Forum: Troubleshooting
Topic: software shutdown and LED blinking
Replies: 2
Views: 65

software shutdown and LED blinking

When I do a software-directed shutdown of my Raspberry Pi, the activity LED blinks at a fixed rate for a while, then stops. Is it safe to remove power when it is doing this final blink pattern, or is it in fact still writing to the SD card during that time? Reason I ask is that I am using a RPi-powe...
by jbeale
Wed Jul 25, 2018 11:06 pm
Forum: Camera board
Topic: wider Hfov lens for 5mp camera module
Replies: 4
Views: 238

Re: wider Hfov lens for 5mp camera module

I realize there isn't much info here, but: https://elinux.org/Rpi_Camera_Module#Replacing_Stock_Lens As far as I know there is no drop-in replacement for the tiny (non-standard, M6 ?) lens used in the camera module. Easiest thing to do is simply add an external wide-angle adaptor such as are sold fo...
by jbeale
Tue Jul 10, 2018 6:07 am
Forum: Networking and servers
Topic: Connecting Pi to WiFi yagi antenna
Replies: 2
Views: 240

Re: Connecting Pi to WiFi yagi antenna

https://en.m.wikipedia.org/wiki/Long-range_Wi-Fi for what's possible with some hacks
by jbeale
Fri Jun 22, 2018 6:31 pm
Forum: Automation, sensing and robotics
Topic: Raspi-powered seismometer/seismograph
Replies: 63
Views: 33646

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: 6
Views: 430

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: 6
Views: 430

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: 6
Views: 430

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: 1111

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: 657

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: 1780

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: 1643

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: 812

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: 812

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: 678

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: 541

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: 63
Views: 33646

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: 63
Views: 33646

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 ...

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