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by Joel_Mckay
Mon Apr 22, 2019 12:34 pm
Forum: Automation, sensing and robotics
Topic: RF receiver for 926.365 MHz
Replies: 9
Views: 385

Re: RF receiver for 926.365 MHz

The RTL-SDR is a DTV receiver that had its driver enhanced to become a general purpose RF receiver. A common ebay $10 USD 820T version can receive 24 MHz up to 1766 MHz with fairly good signal quality: https://www.youtube.com/watch?v=bSAa2aOXpCc https://www.rtl-sdr.com/about-rtl-sdr/ On a Pi3B+ one ...
by Joel_Mckay
Sun Apr 21, 2019 12:07 pm
Forum: Troubleshooting
Topic: Error while making boot SD card: dd: fsync failed for '/dev/sdd': Input/output error
Replies: 6
Views: 222

Re: Error while making boot SD card: dd: fsync failed for '/dev/sdd': Input/output error

dd doesn't care what bytes it is writing. If dd is giving an error message it is not because the file it is writing is corrupted. Checking the file hash will exclude host source disk i/o access/bad-sector issues, and content integrity errors. I have found dd will ignore most issues with a target sd...
by Joel_Mckay
Sun Apr 21, 2019 8:55 am
Forum: Troubleshooting
Topic: Error while making boot SD card: dd: fsync failed for '/dev/sdd': Input/output error
Replies: 6
Views: 222

Re: Erro while making boot SD card: dd: fsync failed for '/dev/sdd': Input/output error

Check the pi foundation's hash file-signature in case the download dropped part way. ;) We cover several OS specific issues our hobby group encountered with the initial install (gnome "disk-tools" supports xz format natively): http://www.micrometer.xyz/cdn/node/23 Note, some had to use an external s...
by Joel_Mckay
Thu Apr 04, 2019 10:25 pm
Forum: Graphics, sound and multimedia
Topic: Reading data from SD card slot on another device and saving it on Pi memory.
Replies: 1
Views: 252

Re: Reading data from SD card slot on another device and saving it on Pi memory.

Nikon D7000 supports remote tethering
http://gphoto.org/doc/remote/

Depending on the drivers supported features, YMMV
;-)
by Joel_Mckay
Thu Apr 04, 2019 10:18 pm
Forum: Advanced users
Topic: Solution: Dedicating one core to a real-time process
Replies: 9
Views: 2578

Re: Solution: Dedicating one core to a real-time process

Would you be willing to post your code for your loop? I'd like to see how you solved it, to save effort on my end. FPGA solve a different set of problems, and FIR/CIC are used in DSP given the uniformity of timing latency. I am not familiar with the equipment in the photo, but would recommend looki...
by Joel_Mckay
Tue Apr 02, 2019 6:45 pm
Forum: Automation, sensing and robotics
Topic: Remote Tank level sensor queries
Replies: 11
Views: 611

Re: Remote Tank level sensor queries

If it is line of sight, than Lora long-range versions should work if you just need a few hundred bytes per second. Ubiquiti Networks Long Range dishes can reach well over 25km, so just contact their sales people to find a locally compliant model. Point to point links are nice as there is no monthly ...
by Joel_Mckay
Tue Apr 02, 2019 7:56 am
Forum: Automation, sensing and robotics
Topic: Remote Tank level sensor queries
Replies: 11
Views: 611

Re: Remote Tank level sensor queries

If like most places your 2G/2.5G network is being upgraded to LTE or G5, than your GPRS modem is a paper weight. If the GPS firmware is old, than it will stop functioning as the epoch rolls over in the next few months. if you are unable to kludge something together, than a cellular enabled cisco rou...
by Joel_Mckay
Fri Mar 29, 2019 8:28 pm
Forum: Troubleshooting
Topic: Pi won't play sounds from Java Midi Library
Replies: 5
Views: 196

Re: Pi won't play sounds from Java Midi Library

Languages like Java and Python almost always rely on wrapped lower level C/C++ libraries. So much so, an automated tool was created to make this easier: http://swig.org/ If you don''t need to watch mixing/loading times, than Playing any media though a libVLC high-level instance is fairly simple: htt...
by Joel_Mckay
Thu Mar 28, 2019 8:49 pm
Forum: Automation, sensing and robotics
Topic: Mechanical unit automation
Replies: 7
Views: 456

Re: Mechanical unit automation

In general, for industrial applications you will usually use an RTC calendar chip (lke the MCP79412 ) with an embedded mcu that has a real WDT. I have hardened arm boards for long-term headless applications, and would recommend you look into a normal PLC given design certification costs. Best regard...
by Joel_Mckay
Thu Mar 28, 2019 8:40 pm
Forum: Troubleshooting
Topic: Pi won't play sounds from Java Midi Library
Replies: 5
Views: 196

Re: Pi won't play sounds from Java Midi Library

In general, most MIDI is rendered using a soft-bank of audio samples in a large file. Although configuring VLC to find and use fluidsynth files (example: /usr/share/sounds/sf2/FluidR3_GM.sf2 ) is fairly straight forward, creating a jack interface to emulate generic MIDI hardware is a bit more cpu in...
by Joel_Mckay
Mon Mar 25, 2019 9:37 am
Forum: Advanced users
Topic: Adding current temperature to PHP graph script
Replies: 1
Views: 189

Re: Adding current temperature to PHP graph script

In general, I would just use an ajax call to send json formatted data to local html based javascript: https://dojotoolkit.org/reference-guide/1.10/dojox/charting.html Drop the normal (not mini-fied) javascript source into your sites static /js lib folder. Learn to use the library programmatic method...
by Joel_Mckay
Mon Mar 25, 2019 9:23 am
Forum: Troubleshooting
Topic: HDMI screen is blank......tried everything i can think of.
Replies: 4
Views: 151

Re: HDMI screen is blank......tried everything i can think of.

Often the most mysterious problems come from simple issues. 1. unplug everything 2. plug in only the pi HDMI cable into a different TV port 3. Turn your TV On, and choose this different HDMI port known to connect to the PI 4. Make sure to try a different HDMI cable (even new, some brands break inter...
by Joel_Mckay
Wed Mar 20, 2019 6:02 pm
Forum: Troubleshooting
Topic: Adobe Flash plugin for Chromium Stretch?
Replies: 10
Views: 755

Re: Adobe Flash plugin for Chromium Stretch?

But what I have seen so far is remarkable and especially so in light of the fact that this was all done for the sake of proving it possible and not with the aim of amassing wealth. Often, I am in awe of the hundreds of thousands of people that contributed to gnu, Apache group, and Linux kernel effo...
by Joel_Mckay
Tue Mar 19, 2019 5:04 pm
Forum: Troubleshooting
Topic: Adobe Flash plugin for Chromium Stretch?
Replies: 10
Views: 755

Re: Adobe Flash plugin for Chromium Stretch?

May take me a few iterations to get this right... but thanks for your input. I use midori for youtube and bbc (chromium with adblock for other sites), and have set bleachbit to wipe the web/flash caches on login. This is a disk clone of what I use for building my own projects, and includes a very m...
by Joel_Mckay
Mon Mar 18, 2019 5:07 pm
Forum: Troubleshooting
Topic: Adobe Flash plugin for Chromium Stretch?
Replies: 10
Views: 755

Re: Adobe Flash plugin for Chromium Stretch?

Re: Midori. I found their web site at midori.org; it is certainly minimalist. Is there anything I need to know before downloading it? Wrong URL, try https://www.midori-browser.org/ and we used the deb source repo: wget http://deb.debian.org/debian/pool/main/m/midori/midori_0.5.11-ds1.orig.tar.bz2 A...
by Joel_Mckay
Mon Mar 18, 2019 4:47 pm
Forum: Troubleshooting
Topic: Adobe Flash plugin for Chromium Stretch?
Replies: 10
Views: 755

Re: Adobe Flash plugin for Chromium Stretch?

chromium-browser should have pepperflash by default, try Scratch2 as that uses Flash ! Raspbian Stretch did not seem to show this default support with the install process we followed... We already unsuccessfully tried the old method of editing: /etc/chromium-browser/default CHROMIUM_FLAGS="--use-gl...
by Joel_Mckay
Mon Mar 18, 2019 5:04 am
Forum: Troubleshooting
Topic: Is this a Raspberry Pi problem or SD card problem?
Replies: 12
Views: 633

Re: Is this a Raspberry Pi problem or SD card problem?

Reformat as HawaiianPi says, try a newer usb-to-microsd card adapter, and finally scan the card for storage defects. Even a full reformat will not catch looping-write firmware counterfeits, or flash cells with amnesia after the internal card cache expires. We use AltraMayor's f3 (Fight Flash Fraud) ...
by Joel_Mckay
Mon Mar 18, 2019 1:26 am
Forum: Troubleshooting
Topic: Adobe Flash plugin for Chromium Stretch?
Replies: 10
Views: 755

Re: Adobe Flash plugin for Chromium Stretch?

We use flash 32.0.0.1 in midori on pi3B+ to watch BBC streaming media.
https://sourceforge.net/projects/microm ... pberry-pi/

Like most modern browsers, chromium probably removed default legacy support for the flash plugin.
I am not sure if it is possible with chromium now.

Cheers,
J
by Joel_Mckay
Sun Mar 17, 2019 4:06 am
Forum: Troubleshooting
Topic: Sources.List - managed to mess it up while trying to download OpenCPN
Replies: 3
Views: 289

Re: Sources.List - managed to mess it up while trying to download OpenCPN

We do demos with openCPN 4.99 using the rtl-sdr AIS path-plotter plug-in (you would have to download the charts for your area):
https://sourceforge.net/projects/microm ... pberry-pi/

It would be great if a better repo version is available. =)

Cheers,
J
by Joel_Mckay
Sat Mar 09, 2019 2:59 pm
Forum: Automation, sensing and robotics
Topic: New Project with relay and sensors. Help needed.
Replies: 1
Views: 223

Re: New Project Help

In general, for safety reasons people tend to separate machine control loops into smaller/simpler micro-controllers, and send messages from a host running more complex software. There are Programmable logic controller (PLC) that are designed for industrial uses, but the Pi is intended for consumer g...
by Joel_Mckay
Fri Mar 01, 2019 5:29 am
Forum: Troubleshooting
Topic: RASPBERR PI IS NOT BOOOTING
Replies: 5
Views: 219

Re: RASPBERR PI IS NOT BOOOTING

Did you insert a cable while the device was running? On the Pi, I found one can't even get away with hot-plugging USB devices sometimes without causing it to reboot. Note, other plugs are not like USB, and can brick the hardware if hot-plugged. ;-) Disconnect the power, remove the camera cable, and ...
by Joel_Mckay
Wed Feb 27, 2019 9:16 am
Forum: Automation, sensing and robotics
Topic: Control multiple steppers with pigpio wave chains
Replies: 5
Views: 363

Re: Control multiple steppers with pigpio wave chains

While this works, I am now of the opinion it is *much* easier to use much more advanced controller chips, like the trinamic chips, as this provides more advanced controls and functionality while making the code on the pi side pretty trivial If you are addressing the chips over the serial protocol, ...
by Joel_Mckay
Wed Feb 27, 2019 6:39 am
Forum: Troubleshooting
Topic: SD Cards not working- except one bought with Raspberry PI Zero.
Replies: 2
Views: 95

Re: SD Cards not working- except one bought with Raspberry PI Zero.

F3 is one of the few 100% guaranteed capacity/status verification methods: https://fightflashfraud.wordpress.com/ I wrote up a page on how to compile, install, and run F3 from the pi: http://www.micrometer.xyz/cdn/node/78 It will detect most fakes and damage, but not rebranded older slower cards wit...
by Joel_Mckay
Wed Feb 27, 2019 6:22 am
Forum: Graphics, sound and multimedia
Topic: Using two Pi's to overcome the one camera limit
Replies: 3
Views: 295

Re: Using two Pi's to overcome the one camera limit

You could, but have two limitations: 1. Both cpus must have an accurate concept of global time down to 1/60 second 2. The image capture sync will be off up to +-1 frame depending on the cameras relative latch-out buffer event-time mismatch Thus, you need to have a frame-rate of at least twice the in...
by Joel_Mckay
Wed Feb 27, 2019 4:26 am
Forum: Advanced users
Topic: RPI 3A+ or RPI 3B+ for PARALLEL COMPUTING?
Replies: 2
Views: 252

Re: RPI 3A+ or RPI 3B+ for PARALLEL COMPUTING?

OpenCL is still not fully supported by the Pi... but people are working on a port. ;-) It could in theory make the RPi 3B+ 5 to 27 times faster for some problems by adding the full capability of the GPU. However, for parallel-heavy problems you are probably still better off using an Intel i7 CPU, an...

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