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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: 3969

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: 1039

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: 1196

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: 690

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: 1196

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: 1196

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...
by Joel_Mckay
Tue Feb 05, 2019 4:25 am
Forum: Automation, sensing and robotics
Topic: Time log with MPU Vibration sensor
Replies: 2
Views: 465

Re: Time log with MPU Vibration sensor

If this is Lawrence or Peter's group, than note both the MPU-6050 and MPU-9250 are ending manufacture at the end of this year. As to your question, the MPU buffer monitors an external heart-beat input to set a bit-flag that notes the correct time intervals. In general, one should not rely too heavil...
by Joel_Mckay
Sat Feb 02, 2019 6:56 am
Forum: Automation, sensing and robotics
Topic: how to make this ?
Replies: 12
Views: 1367

Re: how to make this ?

Does that controller do spindle speed control? We ported in open Arduino firmware people would be comfortable modding, and the version of GRBL on the distro has been setup to run the 12v 10A PWM (low 1kHz drive for laser triggers) on the spindle out. We mostly use this to run fast little diode-lase...
by Joel_Mckay
Sat Feb 02, 2019 4:53 am
Forum: Automation, sensing and robotics
Topic: how to make this ?
Replies: 12
Views: 1367

Re: how to make this ?

Ok FreeCad on aarch64 Raspbian Debian has a mesa loader issue as expected, Now trying 32bit Raspbian, yep works in 32bit Raspbian. Will also try Gentoo64, that has Mesa 18.3.0, not old Raspbian 13.x Need all these just to make those injector molds ;) We built FreeCad 18.x from the stable head as th...
by Joel_Mckay
Fri Feb 01, 2019 11:55 pm
Forum: Automation, sensing and robotics
Topic: how to make this ?
Replies: 12
Views: 1367

Re: how to make this ?

Love to get a Tormach and Datron Mill for the small stuff. Looks nice, but do you have a photo of the drive gearbox? We got stung by those nylon gearbox designs before, and now have a belt-drive only rule for spindles. (Mostly a human error problem, but chipping a tooth seemed inevitable on the uni...
by Joel_Mckay
Fri Feb 01, 2019 10:12 am
Forum: Automation, sensing and robotics
Topic: how to make this ?
Replies: 12
Views: 1367

Re: how to make this ?

I want one, plus the cnc mill that made those dies, need G-code for that. I rebuilt my mini home machine for LinuxCNC, and regularly post the entire CAD/CAM software tool-chains along with hard-to-find utilities we found useful. FreeCAD "Path" toolbox and HeeksCNC are slow on the pi3B+, but run jus...
by Joel_Mckay
Fri Feb 01, 2019 7:36 am
Forum: Automation, sensing and robotics
Topic: how to make this ?
Replies: 12
Views: 1367

Re: how to make this ?

Please ensure to enclose this type of machinery with a blast-shield, as pressurized molten plastic can be dangerous. Stream pressure from residual water in the plastic can cause all sorts of really nasty accidents. However, I suspect this user is probably just using a Marlin (atmega2560) based contr...
by Joel_Mckay
Fri Feb 01, 2019 6:50 am
Forum: Automation, sensing and robotics
Topic: Which expansion boards should I buy for automation?
Replies: 3
Views: 460

Re: Which expansion boards should I buy for automation?

A lawsuit from an insurance company,,, and or fine from the inspectors.... can cost your company much more than a real PLC.

I have built custom industrial stuff before, and it only really makes economic sense if building over 10k pcs at a time.
;-)

Best of luck,
J
by Joel_Mckay
Wed Jan 30, 2019 8:14 am
Forum: Troubleshooting
Topic: Radar Project Using Ultra Sonic Sensor
Replies: 22
Views: 5704

Re: Radar Project Using Ultra Sonic Sensor

Sonars make great wind-speed indicators, and unreliable distance sensors. ;-) Low cost Radars are a real option now, and worth looking at given the example code is for a PI if I recall: https://www.acconeer.com/products https://www.digikey.com/product-detail/en/acconeer-ab/A111/1891-1000-ND/8040771 ...
by Joel_Mckay
Tue Jan 29, 2019 2:19 am
Forum: Advanced users
Topic: Handling UART interrupt on Raspbian OS
Replies: 7
Views: 2519

Re: Handling UART interrupt on Raspbian OS

I actually have implemented serial communication using termios.h . Fortunately, it seemed to work well with 1Mbps baud rate although manual said me not to do that. With most FTDI USB-to-serial adapters they have much larger fifo buffers than classic hardware uarts, and easily achieve 3MBaud with th...
by Joel_Mckay
Mon Jan 28, 2019 11:29 am
Forum: Advanced users
Topic: Handling UART interrupt on Raspbian OS
Replies: 7
Views: 2519

Re: Handling UART interrupt on Raspbian OS

There are a number of ways to handle the UART buffers in Linux, and it is somewhat limited by which driver you are using. Normally, a threaded C program will simply use a blocking Canonical mode with buffer reads terminated by '\n', and consumes negligible cpu time while waiting for a key character ...
by Joel_Mckay
Sun Jan 27, 2019 9:04 am
Forum: Troubleshooting
Topic: Pi v2 Camera Corrupts SD card
Replies: 5
Views: 382

Re: Pi v2 Camera Corrupts SD card

No, the camera cannot interfere with the HAT I2C. My mistake, as it has been a few years.... this was probably what I was thinking about. I'm not sure there is a fix. At least not with sane timescales. The problem as I remember it is that the GPU need access to the I2C to talk to the camera. If you...
by Joel_Mckay
Sun Jan 27, 2019 3:18 am
Forum: Troubleshooting
Topic: updating jessie to stretch
Replies: 3
Views: 1199

Re: updating jessie to stretch

I tried this and it didn't end cleanly, as there seemed to be several hard to replicate bugs after it completed. It would be wise to simply use a fresh/clean foundation raspbian install, and simply import your deb package list selections. One could also try out a pre-setup distro we maintain for our...
by Joel_Mckay
Sun Jan 27, 2019 3:09 am
Forum: Troubleshooting
Topic: Pi v2 Camera Corrupts SD card
Replies: 5
Views: 382

Re: Pi v2 Camera Corrupts SD card

First try it with CVLC to see if it is still hanging the system. As a precaution, disable the HAT eeprom i2c bus, as the Camera module can interfere with i2c bus access. In theory, an open-collector bus drive contention can't cause a "short", but can corrupt the protocol in bizarre ways. Other than ...
by Joel_Mckay
Tue Jan 22, 2019 12:06 am
Forum: Troubleshooting
Topic: Think I've got an sd card problem, but want to rule out anything worse.
Replies: 8
Views: 1177

Re: Think I've got an sd card problem, but want to rule out anything worse.

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 flash-drives are of the lowest quality type. Also, not all USB-to-SATA adap...
by Joel_Mckay
Wed Jan 16, 2019 5:49 am
Forum: Advanced users
Topic: interfacing with matlab & simulink - is it free
Replies: 4
Views: 1239

Re: interfacing with matlab & simulink - is it free

The open Octave is fairly similar to Matlab, and Julia is the super-computing option.
https://julialang.org/learning/

There are no shortcuts in learning how to write software, but python is a good place to start.
by Joel_Mckay
Fri Jan 11, 2019 7:30 pm
Forum: Advanced users
Topic: accessing device connected in eth0
Replies: 2
Views: 587

Re: accessing device connected in eth0

In general, a good VPN will create a local virtual network device, and sand-boxed networks. After a client connects to the tunnel, a local IP is assigned for each remote user in the sand-boxed network. The admin must then decide how to route packets between the sand-boxed area, and other actual LAN ...
by Joel_Mckay
Tue Jan 08, 2019 3:47 am
Forum: Advanced users
Topic: syslog - is someone rerouting data to another site?
Replies: 2
Views: 1413

Re: syslog - is someone rerouting data to another site?

Access attempts are usually logged to: sudo tail -n 100 /var/log/auth.log The Xwindows GUI layer does open local connections to system resources you need to use, and can be reviewed with: sudo netstat | grep 'X11' If you want to monitor network activity, than wireshark is the standard tool. However,...
by Joel_Mckay
Mon Jan 07, 2019 7:23 pm
Forum: Troubleshooting
Topic: Stuck! Cannot SSH or Ping with new Pi3 on Stretch
Replies: 10
Views: 1415

Re: Stuck! Cannot SSH or Ping with new Pi3 on Stretch

Some wifi routers disable cross forwarding between network areas. Our local club desktop image also enables ufw basic firewall by default, as we saw some users getting tagged by annoying traffic on the ssh port (i.e. few inexperienced users would know/bother to change the default password on standar...
by Joel_Mckay
Fri Jan 04, 2019 5:40 pm
Forum: Graphics, sound and multimedia
Topic: Is Openscad ported to Raspbian Stretch?
Replies: 20
Views: 8579

Re: Is Openscad ported to Raspbian Stretch?

@scruss I was hoping our clubs forced qt4 built version was finally getting an update to qt5 with better gpu acceleration. ;-) It would have been nice to finally get that graphics driver lib issue in qt5 finally solved, as it broke several other packages. We just released the rc1 version of our desk...

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