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by Joel_Mckay
Wed Jan 02, 2019 7:06 pm
Forum: Troubleshooting
Topic: Strange issue with main menu language
Replies: 9
Views: 292

Re: Strange issue with main menu language

Try reset of local menu config:
mv ~/.config/lxpanel ~/lxpanel_bak
sudo shutdown -r now


Usually screenshot capture is possible by pressing print screen button
by Joel_Mckay
Wed Jan 02, 2019 5:50 pm
Forum: Troubleshooting
Topic: Strange issue with main menu language
Replies: 9
Views: 292

Re: Strange issue with main menu language

Did you delete menu cache in local user directory?
Then reboot.

=)
by Joel_Mckay
Wed Jan 02, 2019 3:18 pm
Forum: Troubleshooting
Topic: Strange issue with main menu language
Replies: 9
Views: 292

Re: Strange issue with main menu language

You may have to look for the *.desktop files for the lxpanel configuration. https://unix.stackexchange.com/questions/177386/how-can-i-add-applications-to-the-lxpanel-application-launch-bar-via-cli#177839 Sometimes the label strings need changed for a specific language translation and sent to the deb...
by Joel_Mckay
Mon Dec 31, 2018 11:07 pm
Forum: Troubleshooting
Topic: Strange issue with main menu language
Replies: 9
Views: 292

Re: Strange issue with main menu language

1. Open terminal with Crtl+t

2. Type:
sudo dpkg-reconfigure locales

3. Reboot system

Cheers,
J
by Joel_Mckay
Mon Dec 31, 2018 11:04 pm
Forum: Troubleshooting
Topic: Rpi 3 b+ will not boot
Replies: 2
Views: 229

Re: Rpi 3 b+ will not boot

Some of our members had issues with etcher on a few windows machines (tried both 32bit and 64bit versions).
The old 7zip + Win32 Disk imager method does seem to work in most cases if etcher throws write errors: https://www.micrometer.xyz/cdn/node/94

Cheers.
J
by Joel_Mckay
Sun Dec 30, 2018 7:38 pm
Forum: Automation, sensing and robotics
Topic: Replacing DRV 8825 with Trinamic 2130
Replies: 2
Views: 292

Re: Replacing DRV 8825 with Trinamic 2130

Depends what you are building, as I tend to use Pololu A4988 modules in half-step mode. This is mostly because the type of mechanical load we see on a CNC machine requires a motor with high-holding torque, and a fractional position that aligns to the pitch of the axis screw (for example, 800 steps p...
by Joel_Mckay
Sat Dec 29, 2018 3:53 pm
Forum: Troubleshooting
Topic: OS RPI3b and 3b+
Replies: 4
Views: 254

Re: OS RPI3b and 3b+

As the above posters noted, the regular Raspbian Stretch Desktop will have the most support for new users. Best option in my opinion too. Note, our club also shares a pre-configured Raspbian Desktop we use in our group, that has around 40+ additional lib builds (the source code urls are listed too):...
by Joel_Mckay
Wed Dec 26, 2018 1:53 pm
Forum: Graphics, sound and multimedia
Topic: Slightly glitchy sound producing tones via GPIO pins
Replies: 7
Views: 622

Re: Slightly glitchy sound producing tones via GPIO pins

BTW, I am pretty new to electronics, so a lot of stuff is going to be over my head. There are many ways to look at a phenomena, and usually I try to initially get an intuitive understanding of how something works. Otherwise, a detailed explanation of an abstracted model is not really that useful. ;...
by Joel_Mckay
Tue Dec 25, 2018 3:59 pm
Forum: Graphics, sound and multimedia
Topic: Slightly glitchy sound producing tones via GPIO pins
Replies: 7
Views: 622

Re: Slightly glitchy sound producing tones via GPIO pins

It is usually a bad idea to direct drive anything from a logic gate, and at the bare minimum a small low voltage FET or Darlington transistor should be considered. The snubber diode also dampens the motion of the speaker, and will cause some additional distortion in your tone. Note that square-waves...
by Joel_Mckay
Mon Dec 24, 2018 3:22 pm
Forum: Advanced users
Topic: Best way to controll large number of stepper motors?
Replies: 1
Views: 1276

Re: Best way to controll large number of stepper motors?

The 28BYJ-48 motor can be easily modified into a 4 wire bipolar stepper motor by cutting one trace under the blue plastic ( http://www.jangeox.be/2013/10/change-unipolar-28byj-48-to-bipolar.html ). This not only increases the holding torque of the device, but also allows you to use a standard pololu...
by Joel_Mckay
Mon Dec 24, 2018 2:35 pm
Forum: Advanced users
Topic: RPi won't boot with CPLD powered up
Replies: 2
Views: 1035

Re: RPi won't boot with CPLD powered up

I suspect some GPIO have default initial states that may take some time to load i/o configuration from a hat eeprom or kernel overlay. I would recommend having an EN pin on your CPLD logic, and bias the EN pin to keep chip i/o in a high-impedance sleep-state until the system SoC finishes initializin...
by Joel_Mckay
Fri Dec 21, 2018 3:59 am
Forum: Graphics, sound and multimedia
Topic: Sensor Reading to Sound?
Replies: 2
Views: 947

Re: Sensor Reading to Sound?

Are you looking for a simple VCO, or plan on doing some DSP on the input signal?

Most USB sound cards have higher latency associated with buffering both capture and playback streams.

Cheers,
J
by Joel_Mckay
Wed Dec 12, 2018 12:14 pm
Forum: Advanced users
Topic: Piezo sensor + Database
Replies: 6
Views: 3794

Re: Piezo sensor + Database

What makes you think that the OP needs parallel access to the data? Experience building loggers with structures that always eventually degenerated into something that looks like large circular-buffers: ;-) https://en.wikipedia.org/wiki/Producer%E2%80%93consumer_problem https://en.wikipedia.org/wiki...
by Joel_Mckay
Wed Dec 12, 2018 10:41 am
Forum: Advanced users
Topic: Piezo sensor + Database
Replies: 6
Views: 3794

Re: Piezo sensor + Database

SQLite is written in C, and is usually not setup to even be thread safe. Thus, it mainly was intended for a standalone program, and is not great for parallel access to the data. Python often relies on SWiG ( http://swig.org/ ) for all of its performance libs. Likewise, Julia wraps just about everyth...
by Joel_Mckay
Wed Dec 12, 2018 8:37 am
Forum: Automation, sensing and robotics
Topic: Looking to do a project and I have no idea what I'm doing
Replies: 2
Views: 249

Re: Looking to do a project and I have no idea what I'm doing

Aprs on a pi3 (usb sound card + UART based gpio ) https://www.marcelpost.com/wiki/index.php/Aprs There are multi-drop gateways people have made: https://github.com/elafargue/aprs-box http://la3t.no/polaricserver Note direwolf is usually 95% of what people need ;-) We tend to play with the older RTL-...
by Joel_Mckay
Wed Dec 12, 2018 7:43 am
Forum: Troubleshooting
Topic: RPi3 Freeze
Replies: 11
Views: 1444

Re: RPi3 Freeze

@wg141124 Check the drive free space, and list your device mounts. df -h mount The Read-Only errors can be caused by ignoring a partitions "ro" flag, OS error/crash forced re-mount into safe mode, and or the Flash memory is quietly failing. I suspect with a write-heavy server running that your flash...
by Joel_Mckay
Wed Dec 12, 2018 7:32 am
Forum: Advanced users
Topic: Piezo sensor + Database
Replies: 6
Views: 3794

Re: Piezo sensor + Database

MySQL syntax may have changed, but the db user privileges are usually mostly separate from the system user privileges. For example, root user here is mysql's root password, and not a system login password. sudo /usr/bin/mysql_secure_installation mysql -h localhost --user="root" --password="admin_pas...
by Joel_Mckay
Wed Dec 12, 2018 7:13 am
Forum: Advanced users
Topic: Solution: Dedicating one core to a real-time process
Replies: 9
Views: 2855

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

Guaranteed latency OS like LinuxRT essentially install a program as a kernel module.
;-)
Our clubs rc1 variant of Stretch with this kernel will be out Dec. 28, 2018 (includes many updates):
https://sourceforge.net/projects/microm ... pberry-pi/

Cheers,
J
by Joel_Mckay
Sat Dec 08, 2018 11:34 am
Forum: Automation, sensing and robotics
Topic: HELP - Stewart Platform
Replies: 3
Views: 496

Re: HELP - Stewart Platform

a linuxCNC Hexapod uses 6-axis odd kinematics models, and the pi3B+ can barely handle our Cartesian setup. The RT kernel we use is here: https://sourceforge.net/projects/micrometer-cnc-on-raspberry-pi However, I suspect you may find a Pi's limited resources difficult to use for this type of robotics...
by Joel_Mckay
Fri Dec 07, 2018 1:32 am
Forum: Graphics, sound and multimedia
Topic: Compact flash card media players
Replies: 1
Views: 400

Re: Compact flash card media players

Depends what you are doing, and how accurate the timing needs to be. You might be able to do live parallel steams from a VLC rtsp server, and hope the buffers stay relatively well matched. Due to networking and gpu-decoder Latency, the playback mismatch will be difficult to sync up. There are also s...
by Joel_Mckay
Fri Dec 07, 2018 12:38 am
Forum: Troubleshooting
Topic: Data Retrieval from corrupted file system raspberry pi SD card
Replies: 5
Views: 428

Re: Data Retrieval from corrupted file system raspberry pi SD card

Power brown-outs during a write operation can damage some sdcards at the hardware level, and even a surface test may not necessarily show the failed writes. You could use F3 (Fight Flash Fraud) on the pi to flood the drive capacity with pattern files to check for errors ( http://www.micrometer.xyz/c...
by Joel_Mckay
Mon Dec 03, 2018 1:40 am
Forum: Troubleshooting
Topic: Audio problem
Replies: 1
Views: 229

Re: Audio problem

Some updates will force power cycling the SoC to fix it: http://www.micrometer.xyz/cdn/node/74 Also directly check your speakers from the sound utility to make sure nothing is muted ;-) Cheers, J Tip: Also note, on some systems the repo-detached bin dependencies of the files may require you rebuild ...
by Joel_Mckay
Sun Dec 02, 2018 11:02 am
Forum: Advanced users
Topic: Would a backup-script also copy mounted drives?
Replies: 4
Views: 803

Re: Would a backup-script also copy mounted drives?

Although programs like rsync will let you stop at mount points (and stay in one filesystem) yep, see "-x" or "--one-file-system" flag ;-) I simplified a script, so other forum users can adapt it as needed. Cheers, J #!/bin/bash # Joels simple backup script demo # 2018 Dec 2 #bandwidth limit in kiB/...
by Joel_Mckay
Fri Nov 30, 2018 11:08 pm
Forum: Advanced users
Topic: f2fs : why not distribution with root fs as f2fs
Replies: 14
Views: 2911

Re: f2fs : why not distribution with root fs as f2fs

I don't understand the sense of "f2fs might be faster..." sentence in relation with the clock of the device I suspect the communication overhead with F2FS may appear more efficient with a linear write in some scenarios (like avoiding partial erasure that can cause a read, modify, and write routine)...
by Joel_Mckay
Thu Nov 29, 2018 7:45 am
Forum: Advanced users
Topic: f2fs : why not distribution with root fs as f2fs
Replies: 14
Views: 2911

Re: f2fs : why not distribution with root fs as f2fs

XDA: Interview with Francisco Franco... September 3, 2017. quote a Google engineer which says that based on their test, F2FS doesn’t perform any faster than the ext4 . (Kinda of a poor reference without any details) Have newer SD cards demonstrated better speeds. Maybe it's time to take another loo...

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