Go to advanced search

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: 270

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...
by Joel_Mckay
Wed Feb 27, 2019 4:03 am
Forum: Automation, sensing and robotics
Topic: Setting up MLX90640
Replies: 4
Views: 1670

Re: Setting up MLX90640

In general, you need to setup the pi kernel overlays and modules to allow port access. We maintain a OverlayFS based desktop for our local CNC/3d-printer club, that already has these enabled (we played with the Lepton FLIR modules at one point) along with the recent libraries: bcm2835 libi2c-dev lib...
by Joel_Mckay
Wed Feb 27, 2019 3:20 am
Forum: Automation, sensing and robotics
Topic: Control multiple steppers with pigpio wave chains
Replies: 5
Views: 433

Re: Control multiple steppers with pigpio wave chains

Our group builds photo-plotters, uses many CNC platforms, and runs the RTLinux kernel: https://sourceforge.net/projects/micrometer-cnc-on-raspberry-pi There are a few issues one may encounter with how you are trying to build your project. There are several people who publish Pi direct-gpio based NC ...
by Joel_Mckay
Sun Feb 24, 2019 11:01 am
Forum: Automation, sensing and robotics
Topic: Choosing motors
Replies: 36
Views: 2897

Re: Choosing motors

Post #2, stepper motors with gearboxes for £1.54? How physically small, how much torque possible from them? I'd be interested to know for future projects of my own. Modding the 5v version of the $1.60 28BYJ-48 for the more powerful bipolar mode is easy, and allows on to use current-regulated Pololu...
by Joel_Mckay
Sat Feb 23, 2019 2:11 pm
Forum: Automation, sensing and robotics
Topic: Choosing motors
Replies: 36
Views: 2897

Re: Choosing motors

You probably could use $2 stepper motors with gear-boxes for such a small platform (700g/cm). This would allow you to easily keep the two wheels on each side synced while moving. However, you may want to think about the zero turning radius a normal turtle-bot platform gets with only 2 motors (have a...
by Joel_Mckay
Sat Feb 23, 2019 1:46 am
Forum: Troubleshooting
Topic: I tried many GSM modules with RPI 3B+ but no response
Replies: 5
Views: 427

Re: I tried many GSM modules with RPI 3B+ but no response

What i want to do is to control my raspberry pi using sms or by calling the raspberry what you reckon is the easiest and best solution for this and please provide me with the name of the chip so i can use it You will need to match a USB or Mini PCIe device with your country specific carrier bands a...
by Joel_Mckay
Fri Feb 22, 2019 3:12 am
Forum: Troubleshooting
Topic: I tried many GSM modules with RPI 3B+ but no response
Replies: 5
Views: 427

Re: I tried many GSM modules with RPI 3B+ but no response

The sim900 is a GPRS / GSM G2 modem, and most places have already deployed LTE. A normal GPRS connection is impossible if you live in a place that has already deprecated GSM services. The modem-manager also has a plugin specific to cellular modems, and it can be easy to setup connections if you purc...
by Joel_Mckay
Thu Feb 21, 2019 3:20 pm
Forum: Automation, sensing and robotics
Topic: Installing OpenCV 4.0 in RaspberryPi without virtualenvironment.
Replies: 6
Views: 1897

Re: Installing OpenCV 4.0 in RaspberryPi without virtualenvironment.

Native builds on the pi are slow (must use the single instance of make ), but tends to allow better environment detection of platform specific flag optimizations. The packaged opencv versions are usually older stable generic-armhf snapshots, and your make scripts will need to account for the custom ...
by Joel_Mckay
Thu Feb 21, 2019 12:53 pm
Forum: Advanced users
Topic: 3G in raspian
Replies: 3
Views: 430

Re: 3G in raspian

Most countries have gone LTE, and thus use region specific certified hardware. In the old G2 network there was global GPRS coverage due to the standard limited set of GSM/HSPA bands, and the way networks handled data connections. Today, there is currently no longer universal coverage for G3/G4, and ...
by Joel_Mckay
Thu Feb 21, 2019 3:22 am
Forum: Troubleshooting
Topic: Can't connect to pi3 b+ from other computers on LAN
Replies: 5
Views: 245

Re: Can't connect to pi3 b+ from other computers on LAN

Try:
sudo ufw disable
.
Make sure your host OS firewall rules allows connections to other LAN hosts (Win10 may require manual tweaks).

Also check if your router has an option that allows cross forwarding traffic from wifi-to-LAN, and or disables host-to-host in-zone connections.

Cheers,
J
by Joel_Mckay
Thu Feb 21, 2019 3:12 am
Forum: Automation, sensing and robotics
Topic: Sensor to detect Vape smoke
Replies: 4
Views: 785

Re: Sensor to detect Vape smoke

Any sensor that can see VOC should show a relatively large ppm count increase from many aromatic hydrocarbons.
I haven't personally tried the bme680 yet, but the CCS811 does seem to work rather well.

Cheers,
J
by Joel_Mckay
Tue Feb 19, 2019 10:49 pm
Forum: Troubleshooting
Topic: RPI 3 b+ don't boot after reboot and stop working after an hour
Replies: 6
Views: 402

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

Sounds like worn out flash... do the S3 scan after reformatting the disk to make sure. Please document the card brand, model, and retail source for other users. Many people have similar issues if they didn't' buy the card from a reputable source, use the wrong type of memory, or overclocked beyond n...
by Joel_Mckay
Sun Feb 17, 2019 1:23 pm
Forum: Automation, sensing and robotics
Topic: Installing OpenCV 4.0 in RaspberryPi without virtualenvironment.
Replies: 6
Views: 1897

Re: Installing OpenCV 4.0 in RaspberryPi without virtualenvironment.

This should get you on the right path:
https://solarianprogrammer.com/2018/12/ ... -raspbian/

Hint: run a native build on the pi, and ignore the cross-compiling part of the instructions.
;-)
by Joel_Mckay
Sun Feb 17, 2019 1:19 pm
Forum: Graphics, sound and multimedia
Topic: Bulletproof, lightweight video camera app
Replies: 5
Views: 894

Re: Bulletproof, lightweight video camera app

You mean like sudo apt-get install cheese for webcams or like the common:
mplayer -fps 1 tv:// -tv driver=v4l2:device=/dev/video0:width=320:height=240
( http://wiki.raspberrytorte.com/index.ph ... r_a_Webcam )

Did you really try google before posting? ;-)
by Joel_Mckay
Sun Feb 17, 2019 5:14 am
Forum: Troubleshooting
Topic: Overheating SD Card - Smoke
Replies: 2
Views: 301

Re: Overheating SD Card - Smoke

Expanding on what HawaiianPi has already stated: there is a huge counterfeiting problem from most online re-sellers, auction sites, and community message boards. I would recommend looking at how to use S3 scans, and also dump the card firmware date code & device id information from your new cards.. ...
by Joel_Mckay
Sat Feb 16, 2019 1:44 am
Forum: Automation, sensing and robotics
Topic: Any advice for a pi beginner looking to create a control system on the pi?
Replies: 1
Views: 256

Re: Any advice for a pi beginner looking to create a control system on the pi?

Most cars have ODBII, but motorcycles never really standardized their CAN bus interfaces. This means you are often having non-fun decoding the proprietary system status/diagnostic messages if you want access to sensor data. Note most vehicle manufacturers will never share this information with third...
by Joel_Mckay
Fri Feb 15, 2019 2:27 pm
Forum: Troubleshooting
Topic: RPI 3 b+ don't boot after reboot and stop working after an hour
Replies: 6
Views: 402

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

An S3 scan is one of the few ways to detect a failing-card that no longer can reliably modify the contents of a sector. http://www.micrometer.xyz/cdn/node/78 You may be lucky and miss a damaged area... but may also still encounter random bugs. Have a look at the kernel settings we use to prioritize ...
by Joel_Mckay
Fri Feb 15, 2019 11:41 am
Forum: Automation, sensing and robotics
Topic: High reliability, high accuracy temperature/humidity sensor
Replies: 11
Views: 1167

Re: High reliability, high accuracy temperature/humidity sensor

True 1-wire is pretty reliable on the Pi. The DHT sensors use a different single wire interface. If you read the datasheets you should notice that they do not mention 1-wire anywhere. True, the example DHT polling libs are usually more likely to have timing issues being invoked from user-space... b...
by Joel_Mckay
Fri Feb 15, 2019 6:14 am
Forum: Troubleshooting
Topic: RPI 3 b+ don't boot after reboot and stop working after an hour
Replies: 6
Views: 402

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

If you are using a write heavy program the flash may wear out prematurely. SLC flash is still manufactured, and is good for over 100k writes. MLC ("Sandisk ultra", and most others) flash about 10k writes. TLC are only good for under 5k writes, but in my experience can be under 1.4k writes. Most USB ...
by Joel_Mckay
Fri Feb 15, 2019 6:08 am
Forum: Automation, sensing and robotics
Topic: High reliability, high accuracy temperature/humidity sensor
Replies: 11
Views: 1167

Re: High reliability, high accuracy temperature/humidity sensor

I like to use the bme280 or a mcp9808 ( free samples https://www.microchip.com/wwwproducts/en/mcp9808 ). Being i2c, they are low-power, clock-skew tolerant digital interfaces, and are comparatively reliable/repeatable... Just keep an eye on the 7-bit bus address allocation needs before you order chi...
by Joel_Mckay
Fri Feb 15, 2019 5:37 am
Forum: Advanced users
Topic: Read-only fs (on purpose!), problems with ssl/time
Replies: 7
Views: 444

Re: Read-only fs (on purpose!), problems with ssl/time

I ran into something similar on a headless system... Where if the NTP daemon is running as your time source, it will complain if you jump too far forwards in time (after a few days offline). I simply added a call to sudo ntpd -gq to force the correct time upon boot-up regardless of the error. One ca...
by Joel_Mckay
Fri Feb 08, 2019 6:36 am
Forum: Automation, sensing and robotics
Topic: Solar battery bannk monitoring
Replies: 6
Views: 584

Re: Solar battery bannk monitoring

DC Field sensors like those in clamp-on meters will need periodic zeroing, as they tend to drift over time. Thus, many people prefer those 100A Current-Shunts with a digital LED watt-meter, as each meter is isolated from each other. One is unlikely going to get much accuracy from $14 models like PZE...
by Joel_Mckay
Thu Feb 07, 2019 2:39 am
Forum: Graphics, sound and multimedia
Topic: Video Processing: Overlay
Replies: 3
Views: 361

Re: Video Processing: Overlay

There are compositing functions in some video mixers, but I don't know if a pi can generate a compatible key with the sensor-text overlay you want. Stabilization in post-production is now fairly easy for low resolution content, but a good motion-control rig is the only option when any mistakes will ...
by Joel_Mckay
Wed Feb 06, 2019 6:33 am
Forum: Automation, sensing and robotics
Topic: Solar battery bannk monitoring
Replies: 6
Views: 584

Re: Solar battery bannk monitoring

Schneider tends to make some good products, but I have talked with many of their customers who lament the lack of interoperability that tends to follow. ;-) You shouldn't be seeing plate damage unless it is dropping below 10.6v on a 12v Lead-acid battery during use, or losing electrolyte from fast-c...
by Joel_Mckay
Wed Feb 06, 2019 2:40 am
Forum: Automation, sensing and robotics
Topic: Solar battery bannk monitoring
Replies: 6
Views: 584

Re: Solar battery bannk monitoring

Usually, there are quite a few MPPT Solar Charge Controllers for under $150 around with data-output ports like rs485 (>100m), and Bluetooth (<20m). Both types of interfaces can be controlled by a Pi with a bit of effort or adapters, but the data formats are usually vendor specific. Personally, I wou...

Go to advanced search