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by T3am5hark
Wed Aug 24, 2016 5:26 pm
Forum: Automation, sensing and robotics
Topic: Multi-Processor Stepper motor control
Replies: 7
Views: 1853

Re: Multi-Processor Stepper motor control

Are all 3 pi's on a common network? If so, then you might consider taking the MUX out of the equation and instead allowing a dedicated process on one of the Pi units drive the motor using remote signalling from the other 3 processes (using either web service, RPC/socket-based, or a message queue sub...
by T3am5hark
Fri Aug 19, 2016 11:19 pm
Forum: C/C++
Topic: Sampling from ADC on SPI
Replies: 3
Views: 1275

Re: Sampling from ADC on SPI

How are you populating the timer struct? I assume it's using ftime? Is it fair to assume that timestamp_msec and next_timestamp_msec are both declared as long long ints? It looks like a pure "busy wait" polling approach - given that you only have to worry about 4ms time windows, you can probably put...
by T3am5hark
Fri Aug 19, 2016 2:33 am
Forum: Automation, sensing and robotics
Topic: Laser Sensing project questions?
Replies: 23
Views: 5301

Re: Laser Sensing project questions?

Here's his code - he's not a programmer by trade so it might be a little rough, but should give you an idea of how he went about it:

https://www.dropbox.com/s/04e3hm1vya9ou ... r.zip?dl=0
by T3am5hark
Thu Aug 18, 2016 4:46 pm
Forum: Automation, sensing and robotics
Topic: Self balancing robot using Raspberry Pi !! PROBLEM !!
Replies: 4
Views: 1719

Re: Self balancing robot using Raspberry Pi !! PROBLEM !!

I'll reiterate on this point that for timing-critical control loops, you generally can't have serial IO happening in the loop. Maybe you can get away with just pulling a few bytes at a time out of the comms buffer and only processing the data every N times through the loop, but I think this is gener...
by T3am5hark
Thu Aug 18, 2016 3:48 pm
Forum: Automation, sensing and robotics
Topic: Laser Sensing project questions?
Replies: 23
Views: 5301

Re: Laser Sensing project questions?

There's also ShootOffApp.com which pretty much packages the solution, but that might defeat the purpose of building your own. I pinged my brother and he's going to send me the Python code he wrote which I'll post somewhere - it basically just looks for an inter-frame step function on the red color p...
by T3am5hark
Wed Aug 17, 2016 11:19 pm
Forum: Automation, sensing and robotics
Topic: Control temperature know of flow heater with RPi
Replies: 2
Views: 1024

Re: Control temperature know of flow heater with RPi

If you decide you want to go the stepper motor route, Adafruit has a project overview and parts list that may be helpful:

https://learn.adafruit.com/adafruits-ra ... s/overview
by T3am5hark
Wed Aug 17, 2016 11:10 pm
Forum: Automation, sensing and robotics
Topic: Control temperature know of flow heater with RPi
Replies: 2
Views: 1024

Re: Control temperature know of flow heater with RPi

Hi there! This one sounds pretty easy - if the knob is quite easy to turn then you can probably get away with a low-end micro tower servo ($2 for a really cheap one, $10 if you spend a little more for metal gear servos). They have pretty good positional accuracy and while the pi isn't ideal for real...
by T3am5hark
Wed Aug 17, 2016 9:15 pm
Forum: Automation, sensing and robotics
Topic: Self balancing robot using Raspberry Pi !! PROBLEM !!
Replies: 4
Views: 1719

Re: Self balancing robot using Raspberry Pi !! PROBLEM !!

Hi there! Any time you've got a timing-critical control loop, you probably need to take serial comms out of the loop. Multi-threading the code would be one way to do this and would work much better since your serial could happily be reading data while your motor code is sleeping between bit banging ...
by T3am5hark
Wed Aug 17, 2016 8:47 pm
Forum: Automation, sensing and robotics
Topic: Yet more MPU6050 demo code
Replies: 122
Views: 110683

Re: Yet more MPU6050 demo code

Hej! Nice work. I was wondering what highest logging frequency you get is. How hard world it be to log 1000 sampels a second and save the data to the sd. I have a Rpi and the mpu6050. I am coming from Arduino and not really sure where to start. Hi there - one option you've got is to do a "pi-duino"...
by T3am5hark
Wed Aug 17, 2016 8:28 pm
Forum: Automation, sensing and robotics
Topic: Laser Sensing project questions?
Replies: 23
Views: 5301

Re: Laser Sensing project questions?

Hi Kevin, My brother did almost this exact project (but with a PC rather than a pi). He did it with OpenCV (he built the image processing in Python on top of OpenCV). OpenCV has a ton of capability but is a little bit daunting from the outset. That's probably your best bet for image processing appli...
by T3am5hark
Wed Aug 17, 2016 8:05 pm
Forum: Automation, sensing and robotics
Topic: send data sensor to hosting server
Replies: 3
Views: 3212

Re: send data sensor to hosting server

Can you elaborate on the "real time" component? How much data are we talking, and what frequency of transmission? If it's continuous / real-time updates, this will probably either push you more in the RPC direction (or possibly doing some pi-side batching with less frequent dumps to a web service). ...
by T3am5hark
Wed Aug 17, 2016 8:01 pm
Forum: Automation, sensing and robotics
Topic: send data sensor to hosting server
Replies: 3
Views: 3212

Re: send data sensor to hosting server

Is your pi on the same network as the MySQL host? Or is it remote (going over the internet)? If it's the latter, you probably don't want to open up your DB to the whole internet, and would be better off putting a service front-end on the host machine so you limit the external interface. A web servic...
by T3am5hark
Wed Aug 17, 2016 7:46 pm
Forum: Automation, sensing and robotics
Topic: Supercapacitor UPS for more power reliability
Replies: 9
Views: 7216

Re: Supercapacitor UPS for more power reliability

That's super cool. I'm curious how much the supercaps cost relative to the pi itself.

I'm interested in projects leveraging solar and it seems like this might be able to help with high peak load or intermittent sunlight on a solar panel as well.
by T3am5hark
Wed Aug 17, 2016 7:42 pm
Forum: Automation, sensing and robotics
Topic: Network Control Interfaces for Pi
Replies: 1
Views: 555

Re: Network Control Interfaces for Pi

Here's a demo of ControlSocket being used to remotely steer a web cam:

http://raspberrypicam.blogspot.com/2016 ... again.html
by T3am5hark
Wed Aug 17, 2016 2:47 am
Forum: Networking and servers
Topic: Control server program
Replies: 3
Views: 1119

Re: Control server program

If you're willing to guinea pig the latter in particular I'd be interested in the feedback... I'm still soliciting testers for it. But the idea there is to make a very simple socket interface with a simple command interface that you can basically map to *whatever* in the back end.
by T3am5hark
Wed Aug 17, 2016 2:44 am
Forum: Networking and servers
Topic: Control server program
Replies: 3
Views: 1119

Re: Control server program

Hi there, I've done some very similar projects and have some examples you might be able to benefit from on GitHub. First, if you look in OliWeb, there's a lot of stuff there including use of JQuery from HTML (with Bootstrap) for driving stuff on the pi backend. OliWeb is a web server I wrote specifi...
by T3am5hark
Wed Aug 17, 2016 12:06 am
Forum: Automation, sensing and robotics
Topic: Network Control Interfaces for Pi
Replies: 1
Views: 555

Network Control Interfaces for Pi

I've got two projects out on GitHub designed to allow easy interfacing of external control mechanisms to Raspberry Pi projects if anyone is interested. The first is OliWeb https://github.com/m2ware/OliWeb which is a very lightweight web server with interfaces to talk to the pins on the pi as well as...
by T3am5hark
Tue Aug 16, 2016 11:59 pm
Forum: Automation, sensing and robotics
Topic: Rc Control
Replies: 12
Views: 5695

Re: Rc Control

I have an arduino implementation that can read the PWM signal off of a remote control, but it relies on pin interrupts and probably wouldn't work on a pi. However, I've been fairly successful using serial comms between the arduino and the pi to communicate data, so something like that might work.
by T3am5hark
Thu Mar 17, 2016 2:27 pm
Forum: Networking and servers
Topic: Pi Web Server: testers wanted
Replies: 42
Views: 15055

Re: Pi Web Server: testers wanted

I've just added support for start-on-boot (requiring absolute paths in config file). Would be grateful for some other folks to test this as well.

~Jeff
by T3am5hark
Mon Aug 31, 2015 10:41 pm
Forum: Automation, sensing and robotics
Topic: PWM for servos, motors, and LEDs plus plus
Replies: 71
Views: 45832

Re: PWM for servos, motors, and LEDs plus plus

Excellent! I will definitely give it a go - thanks!
by T3am5hark
Mon Aug 31, 2015 9:52 pm
Forum: Automation, sensing and robotics
Topic: PWM for servos, motors, and LEDs plus plus
Replies: 71
Views: 45832

Re: PWM for servos, motors, and LEDs plus plus

Hi Joan, This is really excellent - I've been complaining vocally for some time about the lack of "arduino-like" pwm control on the pi. I was wondering if you have this working for the pi2 as of yet? I also wrote a GPIO control utility for some projects (mainly servo control) and had to do the follo...
by T3am5hark
Tue Aug 25, 2015 6:22 pm
Forum: Networking and servers
Topic: Pi Web Server: testers wanted
Replies: 42
Views: 15055

Re: Pi Web Server: testers wanted

Excellent - glad it's working for you. Let me know if you hit any more snags!
by T3am5hark
Mon Aug 24, 2015 10:42 pm
Forum: Networking and servers
Topic: Pi Web Server: testers wanted
Replies: 42
Views: 15055

Re: Pi Web Server: testers wanted

Oops - I had a temporary brain failure. The error wasn't with df, it was with invoking df.cgi (the script). Once I changed permissions on the script: chmod 775 df.cgi it worked just fine. Try setting permissions on the script and give it a whirl. Requested File = [/df.cgi] [2015-8-24 17:39:45] Invok...
by T3am5hark
Mon Aug 24, 2015 10:38 pm
Forum: Networking and servers
Topic: Pi Web Server: testers wanted
Replies: 42
Views: 15055

Re: Pi Web Server: testers wanted

Quick Question ..... I hope this is the correct place to ask this. I've set up Oliweb and I think it's pretty great. I'm just using the sample stuff inside to play and test it... So in cgi-bin i put something to check mounted volumes called df.cgi in it I put: df -h I get no output. What did I miss...
by T3am5hark
Sat Sep 27, 2014 4:10 am
Forum: Networking and servers
Topic: Pi Web Server: testers wanted
Replies: 42
Views: 15055

Re: Pi Web Server: testers wanted

As I wrote to you previously, I have a small issue: If you submit an empty box in a form, then the result is 1, and not "nothing" as I would have expected. (but I simply made a small script that removes 1 from the result). Sorry for lengthy delay in addressing this - I overlooked the issue in the t...

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