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by Joel_Mckay
Sat Apr 04, 2020 12:36 pm
Forum: Troubleshooting
Topic: Removing power without SD card corruption
Replies: 12
Views: 337

Re: Removing power without SD card corruption

Adding a shutdown button to issue a power-off key press is now rather easy. The corruption issues seemed more prevalent on pi2/3, but is still quite common. A failed card simply ignores updating the content rather than telling the user an area is no longer working. Often, online shops sell counterfe...
by Joel_Mckay
Sat Feb 29, 2020 5:11 am
Forum: Automation, sensing and robotics
Topic: DMX programing for raspberry pi
Replies: 1
Views: 341

Re: DMX programing for raspberry pi

If I recall correctly, there are ways to modify the FTDI USB-to-serial transceiver adapter modules to generate the necessary timings with special driver software. I do not know if anyone built a wrapper script for python yet, but the DMX protocol itself is usually simple enough once proprietary vend...
by Joel_Mckay
Thu Feb 20, 2020 3:49 am
Forum: Automation, sensing and robotics
Topic: What are Realistic CNC X Y Z maximums for a PI CNC
Replies: 2
Views: 290

Re: What are Realistic CNC X Y Z maximums for a PI CNC

Yes, there are ways to run linuxCNC... slowly...
http://www.micrometer.xyz/cdn/node/18

The grbl firmware for low precision belt-drive machines can be very fast for engravers.

FreeCAD now has the Path toolbox which generates 3-axis g-code.

Cheers,
J
by Joel_Mckay
Thu Feb 20, 2020 1:00 am
Forum: Troubleshooting
Topic: Unable to SSH into my RPi
Replies: 3
Views: 195

Re: Unable to SSH into my RPi

Try to check corrupted server files with: sudo apt-get install debsums sudo debsums -sac note only /etc config files, and missing text files should ideally be reported in the audit. Then reinstall your server (after backing-up corrupted binary for later analysis): sudo apt-get purge openssh-server s...
by Joel_Mckay
Wed Feb 19, 2020 7:20 am
Forum: Troubleshooting
Topic: Unable to SSH into my RPi
Replies: 3
Views: 195

Re: Unable to SSH into my RPi

In Bash, after you type your ssh command... run "echo $?" to get the program exit code. Codes: 0=Success 1=Undetermined error in file copy 3=Destination is not directory, but it should be 4=Connecting to host failed 5=Connection lost for some reason 6=File does not exist 7=No permission to access fi...
by Joel_Mckay
Wed Feb 19, 2020 2:31 am
Forum: Troubleshooting
Topic: RPI 3 b+ don't boot after reboot and stop working after an hour
Replies: 8
Views: 2174

Re: RPI 3 b+ don't boot after reboot and stop working after an hour

Wrong name, I should have updated this thread at some point. ;-) How to run AltraMayor's f3 - Fight Flash Fraud on the pi: http://www.micrometer.xyz/cdn/node/78 It floods an offline mounted drive space with hash checked data, so is the only method of catching looping-write sdcard firmware and failed...
by Joel_Mckay
Tue Jul 23, 2019 2:15 am
Forum: Automation, sensing and robotics
Topic: Installing OpenCV 4.0 in RaspberryPi without virtualenvironment.
Replies: 6
Views: 3403

Re: Installing OpenCV 4.0 in RaspberryPi without virtualenvironment.

try your home dir ;-) cd ~ ls -lAh Also, we recently did a OpenCV 3.4.5 build for legacy Stretch based ROS: https://sourceforge.net/projects/micrometer-cnc-on-raspberry-pi/files/2019_jul4_v0.1rc2_current/ I have talked with some of the awesome devs about openCV 4, and specifically about the perils o...
by Joel_Mckay
Sun May 12, 2019 2:19 am
Forum: Advanced users
Topic: i am working on surveillance robot using Rpi 3 b+ need to good algorithm for self navigation
Replies: 5
Views: 758

Re: i am working on surveillance robot using Rpi 3 b+ need to good algorithm for self navigation

Have a look at ROS or MRPT.

You will need to be more specific about the platform, as guidance and navigation are separate classes of problems.

Cheers.
J
by Joel_Mckay
Mon May 06, 2019 6:33 am
Forum: Advanced users
Topic: Seeking the illusive zero write
Replies: 14
Views: 1597

Re: Seeking the illusive zero write

If you use an overlayfs then its only the upper of the merge mount that is readwrite so the only files are ones written to or writing are in ram and fetched from lower by the CoW (copy on write) of the overlayfs. The overlayfs method also allows one to track down which programs tend to slowly flood...
by Joel_Mckay
Fri May 03, 2019 6:43 am
Forum: Automation, sensing and robotics
Topic: Make a real robot
Replies: 18
Views: 3089

Re: Make a real robot

Is ROS necessary for making the robot. Not always, but it will train you how to re-use a standard popular platform, and a minimal remote sensor/driver API. Both these concepts are important for understanding more complex platforms... yet you can start with just the turtle-bot sim demos. And i think...
by Joel_Mckay
Thu May 02, 2019 5:33 pm
Forum: Advanced users
Topic: MQ Gas sensor wire connection
Replies: 3
Views: 698

Re: MQ Gas sensor wire connection

The MCP3008 may require Vref to be less than or equal to Vcc (3.3v)... I'd use a Voltage divider on the sensor output to scale into a safe input range under 2.7v until this property is known.
https://en.wikipedia.org/wiki/Voltage_divider

;-)
by Joel_Mckay
Thu May 02, 2019 5:09 pm
Forum: Automation, sensing and robotics
Topic: Make a real robot
Replies: 18
Views: 3089

Re: Make a real robot

In general, one must make several choices when designing a platform, and define the task you are trying to solve. Like any software specification, having a clearly defined finish line will constrain the complexity of your project. ROS ( https://wiki.ros.org/melodic ) is the current standard of sever...
by Joel_Mckay
Wed May 01, 2019 6:49 am
Forum: Troubleshooting
Topic: Pi 3B+ won't load Google-owned websites
Replies: 8
Views: 534

Re: Pi 3B+ won't load Google-owned websites

All of that will fail 100%. There's no NTP installed in Raspbian by default. Time sync is done with systemd-timedatectl. Even with ntp added after there's no ntpdate any longer (replaced with ntpd -q -g). And yes, 2 of the above lines will likely not work (20% fail to be exact)... depending on the ...
by Joel_Mckay
Wed May 01, 2019 6:27 am
Forum: Troubleshooting
Topic: Pi 3B+ won't load Google-owned websites
Replies: 8
Views: 534

Re: Pi 3B+ won't load Google-owned websites

If your device has a max time adjust forwards limit in NTP, and was left off too long... than SSL issues can occur. Try running: date sudo service ntp stop sudo ntpdate -s us.pool.ntp.org sudo ntpd -gq sudo service ntp start sudo ntpdate -u time.nist.gov date Then reboot the machine to retry your SS...
by Joel_Mckay
Wed May 01, 2019 6:11 am
Forum: Automation, sensing and robotics
Topic: how to write flash memory of mpu6050 for using dmp on board using python
Replies: 1
Views: 545

Re: how to write flash memory of mpu6050 for using dmp on board using python

InvenSense gyros tend to drift pretty badly/fast, and setting a low-pass down-sampling filter only gets you so far. A slower magnetometer is important as it usually offers the only true consistent directional reference using magnetic declination (once calibrated). Unfortunately, these "9-axis" units...
by Joel_Mckay
Tue Apr 30, 2019 11:51 am
Forum: Automation, sensing and robotics
Topic: What is the best way to add IR transmitter/receiver to raspberry pi 3 B+?
Replies: 12
Views: 7754

Re: What is the best way to add IR transmitter/receiver to raspberry pi 3 B+?

They mention a 38KHz amplifier+de-modulator that runs at 3.3v just fine: https://www.adafruit.com/product/157 Keep in mind there are many different remotes, IR wavelengths, and any one of 34/38/40/56 kHz modulations. There were a few receivers that could auto-select several frequencies, but I can't ...
by Joel_Mckay
Tue Apr 30, 2019 7:38 am
Forum: Automation, sensing and robotics
Topic: What is the best way to add IR transmitter/receiver to raspberry pi 3 B+?
Replies: 12
Views: 7754

Re: What is the best way to add IR transmitter/receiver to raspberry pi 3 B+?

sudo apt-get install lirc Then search for a tutorial about setting up the interface: http://alexba.in/blog/2013/01/06/setting-up-lirc-on-the-raspberrypi/ https://learn.adafruit.com/using-an-ir-remote-with-a-raspberry-pi-media-center/lirc This program has been around for a long time. https://gist.git...
by Joel_Mckay
Mon Apr 29, 2019 7:24 am
Forum: Automation, sensing and robotics
Topic: Lightning Sensor and external camera shutter release
Replies: 6
Views: 978

Re: Lightning Sensor and external camera shutter release

This camera likely supports tethering: http://gphoto.org/proj/libgphoto2/support.php People use several tricks to trigger the shutter in a lightning storm, and as they must be fast it usually limits the complexity of the circuit. In general, with a high-end capture rig ( https://www.krontech.ca/ ) y...
by Joel_Mckay
Sat Apr 27, 2019 11:20 pm
Forum: Automation, sensing and robotics
Topic: Random spikes with AM2302 Temperature & Humidity sensor
Replies: 3
Views: 446

Re: Random spikes with AM2302 Temperature & Humidity sensor

The reason many people use the bme280 is that it is reliable, accurate, and repeatable. Swapping sensors can be a pain, but sometimes using a different chip just works out being easier, and wastes less of your time in the long term. https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=239157 Actu...
by Joel_Mckay
Sat Apr 27, 2019 11:09 pm
Forum: Troubleshooting
Topic: Reducing 3b+ ARM clock speed - I/O issues
Replies: 4
Views: 304

Re: Reducing 3b+ ARM clock speed - I/O issues

The reason many people use the bme280 is that it is reliable, accurate, and repeatable. Swapping sensors can be a pain, but sometimes using a different chip just works out being easier, and wastes less of your time in the long term. https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=239157 Actu...
by Joel_Mckay
Sat Apr 27, 2019 7:46 am
Forum: Troubleshooting
Topic: An Introduction to C & GUI Programming
Replies: 1
Views: 226

Re: An Introduction to C & GUI Programming

I usually prefer a native cross platform C++ lib like wxwidgets for GUI stuff: https://wxwidgets.org/ (it has its own set of constraints, but works on most platforms) If wxglade wasn't so unstable, the visual layout scaffold coding experience would be trivial: http://wxglade.sourceforge.net/ https:/...
by Joel_Mckay
Sat Apr 27, 2019 7:27 am
Forum: Troubleshooting
Topic: USB Speaker is detected by EVERYTHING, but this thing refuses to output audio.
Replies: 8
Views: 539

Re: USB Speaker is detected by EVERYTHING, but this thing refuses to output audio.

Raspbian has "Raspberry Pi Desktop" which is a fork of LXDE......... We use a minimal MATE package on the Raspbian Stretch Lite image (MATE image itself seemed out of date), as it was more consistent with traditional Ubuntu/Mint style community documentation and supported a configurable gpu composi...
by Joel_Mckay
Sat Apr 27, 2019 6:52 am
Forum: Troubleshooting
Topic: USB Speaker is detected by EVERYTHING, but this thing refuses to output audio.
Replies: 8
Views: 539

Re: USB Speaker is detected by EVERYTHING, but this thing refuses to output audio.

fruitoftheloom wrote: Why do you believe the OP is running Gnome Desktop .
It is a common issue people may have, and the "volume control applet" is usually more meaningful than "pactl list; aplay -l;" or fumbling in the "alsamixer" terminal interface with F6 menu.

I assumed they are using linux... ;-)
by Joel_Mckay
Sat Apr 27, 2019 6:32 am
Forum: Troubleshooting
Topic: USB Speaker is detected by EVERYTHING, but this thing refuses to output audio.
Replies: 8
Views: 539

Re: USB Speaker is detected by EVERYTHING, but this thing refuses to output audio.

If you have the gnome desktop : 0. exit all active media players 1. right-click Speaker icon in the upper right hand of screen to select "Sound Preferences" 2. click "hardware" tab to see if driver is active 3. click "output" tab and select alternate default output line 4. click "hardware" tab again...
by Joel_Mckay
Sat Apr 27, 2019 6:11 am
Forum: Troubleshooting
Topic: DHT22 Accuraty.
Replies: 2
Views: 310

Re: DHT22 Accuraty.

We use the BME280 (several years of uptime), and I dumped the DHT/SHT units we sampled in the e-waste recycling bucket after testing the repeatability over several months (cleaved the leads off to ensure they stayed gone). I suggest you do the same... as although there will be a few people who insis...

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