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by henryhanselscott
Tue May 19, 2015 5:57 pm
Forum: General discussion
Topic: Stepper motors
Replies: 10
Views: 3509

Re: Stepper motors

I've not been able to find anything capable of operating at 2.8A at 2.5V Again most modern stepper drivers will current limit automatically and micro step like the one I posted in my first response. You can actually use a much higher voltage to power the stepper driver. Often you can supply at leas...
by henryhanselscott
Tue May 19, 2015 4:26 pm
Forum: General discussion
Topic: Stepper motors
Replies: 10
Views: 3509

Re: Stepper motors

one you have chosen is accurate to 0.9 degrees Certain stepper drivers can "micro step" therefore greatly increasing the resolution of the step angle. Only if operated in the "full step" mode then you are limited to the actual step angle of the motor. Most any modern stepper driver has a micro step...
by henryhanselscott
Tue May 19, 2015 3:07 pm
Forum: General discussion
Topic: Stepper motors
Replies: 10
Views: 3509

Re: Stepper motors

My path for learning Python on the Rpi: 1. Installed Geany IDE on the pi 2. Watched as many videos as I could find about Python(3) (1 month) 3. Wrote many, many micro programs to test GPIO functions, communications, creating files with Python, etc. (2 months) 4. Hammered my way through my "real proj...
by henryhanselscott
Mon May 18, 2015 11:09 am
Forum: General discussion
Topic: Stepper motors
Replies: 10
Views: 3509

Re: Stepper motors

There are a lot of unknowns in your post: 1. size of steppers 2. speed of motion 3. precision of movement 4. budget 5. etc. So, for a general answer the easiest method to use a pi for this might be to write a very simple code in Python that reads the barcode data, then sends out a serial command to ...
by henryhanselscott
Thu May 14, 2015 10:04 am
Forum: General discussion
Topic: Learning electronics, for smart people.
Replies: 20
Views: 2947

Re: Learning electronics, for smart people.

Many folks may find the Forrest Mims series of books childish. However, they are the best way that I have found to teach electronics to young and old people. Once I was asked to teach a semester of high school electronics at a private school. They picked my curriculum for me, the typical heavy math ...
by henryhanselscott
Tue Apr 14, 2015 9:00 pm
Forum: General discussion
Topic: Raspberry PI B+ how to provide power with battery
Replies: 4
Views: 1007

Re: Raspberry PI B+ how to provide power with battery

Using a battery straight up is a tall challenge since a battery tends to loose voltage over its discharge cycle. Also, finding a battery or battery bank with 5.2 volt output could pose a challenge as well. The simplest battery power that I have found that will work with a pi is to use a USB battery....
by henryhanselscott
Tue Apr 07, 2015 12:23 pm
Forum: General discussion
Topic: Hiding the underlying OS
Replies: 3
Views: 717

Hiding the underlying OS

In some of my applications I do not want my end user to know that Linux or any other OS for that matter is running in the background. These applications autostart on boot and they cover the entire monitor screen so that no trace of the OS is visible to the operator. The concern here is that if someo...
by henryhanselscott
Mon Apr 06, 2015 4:37 pm
Forum: General discussion
Topic: Help :Can Rpi Runs 24/7 with HDMI output
Replies: 8
Views: 1800

Re: Help :Can Rpi Runs 24/7 with HDMI output

Standard off the shelf 20 inch acer monitor. No heat sink, no fan. Using a HDMI to DVI cable to run the monitor.
by henryhanselscott
Mon Apr 06, 2015 4:08 pm
Forum: General discussion
Topic: Help :Can Rpi Runs 24/7 with HDMI output
Replies: 8
Views: 1800

Re: Help :Can Rpi Runs 24/7 with HDMI output

Running 24/7 in a factory decoding and displaying barcode data to the line operator....no issues.
by henryhanselscott
Thu Apr 02, 2015 5:00 pm
Forum: General discussion
Topic: Can the Raspberry Pi Do Everything a Arduino Can?
Replies: 13
Views: 3575

Re: Can the Raspberry Pi Do Everything a Arduino Can?

Run it for months on a coupla coin cells.
Good point!

One such project that I am considering would be suited well for a micro to run full time on a small solar setup. When it needs the functionality of the pi it would power it up and use it, then power it back down again.
by henryhanselscott
Thu Apr 02, 2015 9:56 am
Forum: General discussion
Topic: Can the Raspberry Pi Do Everything a Arduino Can?
Replies: 13
Views: 3575

Re: Can the Raspberry Pi Do Everything a Arduino Can?

Deterministic real-time operations. My thoughts exactly. I use a microcontroller in combination of the pi. The micro handles things like analog, reading high speed inputs, doing time critical tasks. The pi does everything else like data logging, creating files, accessing the net, and using it as a ...
by henryhanselscott
Mon Mar 30, 2015 5:30 pm
Forum: General discussion
Topic: UPS for Pi?
Replies: 52
Views: 37755

Re: UPS for Pi?

Attached is the solution that I am using. I am NOT an EE, just an experimenter. So if anyone uses the information contained USE AT YOUR OWN RISK. I share it with the intent of education and no guarantee exist that says it is the correct way to do this. This is and has been working on my Rpi2 for sev...
by henryhanselscott
Mon Mar 30, 2015 4:59 pm
Forum: General discussion
Topic: UPS for Pi?
Replies: 52
Views: 37755

Re: UPS for Pi?

Technically they could work, but would not be the preferred solution to your goal. You need something that can carry the pi and stabilize the voltage for a few milliseconds. You could string up a bank of supercaps, but they are better suited for supplying large current loads over time than short bur...
by henryhanselscott
Mon Mar 30, 2015 4:31 pm
Forum: General discussion
Topic: UPS for Pi?
Replies: 52
Views: 37755

Re: UPS for Pi?

Supercaps might not be the right solution, but normal electrolytic caps in the range of 1000uf might be worth a shot just to keep the power stable for a few milliseconds of transition.

Henry
by henryhanselscott
Mon Mar 30, 2015 1:02 pm
Forum: General discussion
Topic: Time Critical GPIO on Rpi2
Replies: 7
Views: 1474

Re: Time Critical GPIO on Rpi2

Premature question above....looking at that information now.
by henryhanselscott
Mon Mar 30, 2015 12:58 pm
Forum: General discussion
Topic: Time Critical GPIO on Rpi2
Replies: 7
Views: 1474

Re: Time Critical GPIO on Rpi2

If you need accurate gpio event times for most purposes you should use my pigpio library.
Somewhat of a newbie question I guess.... How friendly does it play with Python3 as it is written in C? Do you have any Python code examples using it?

Thank you,
Henry
by henryhanselscott
Mon Mar 30, 2015 10:23 am
Forum: General discussion
Topic: Time Critical GPIO on Rpi2
Replies: 7
Views: 1474

Re: Time Critical GPIO on Rpi2

50 microseconds would be ideal for most of my control applications. For comparison, one particular PLC that I use has a scan time of 25 microseconds and it handles most time critical functions within the realm of my applications. Typical uses: Reading encoder counts measuring RC time constants Ultra...
by henryhanselscott
Mon Mar 30, 2015 9:24 am
Forum: General discussion
Topic: Time Critical GPIO on Rpi2
Replies: 7
Views: 1474

Time Critical GPIO on Rpi2

Is any work being done in the area of GPIO now that the pi2 has 4 cores? Doing task like timing the reflective sound of an ultrasonic sensor should be much more accurate with the newer faster processor. It seems like a GPIO module could be optimized and take advantage of the new cores for advanced t...
by henryhanselscott
Fri Mar 27, 2015 11:33 am
Forum: General discussion
Topic: Intended for kids and hijacked by adult hobbyists?
Replies: 19
Views: 2833

Re: Intended for kids and hijacked by adult hobbyists?

Has their ever been any data compiled about the average age of the users here on the forums? Any survey information. My bets are most are older than 18.
by henryhanselscott
Fri Mar 27, 2015 9:53 am
Forum: General discussion
Topic: Intended for kids and hijacked by adult hobbyists?
Replies: 19
Views: 2833

Re: Intended for kids and hijacked by adult hobbyists?

With the Rpi, I am a 47 year old kid.

Henry
by henryhanselscott
Thu Mar 26, 2015 9:41 am
Forum: General discussion
Topic: UPS for Pi?
Replies: 52
Views: 37755

Re: UPS for Pi?

My solution uses 2 100 farad supercaps in series charged by a 5 volt supply through a diode and a 1 ohm power resistor. The supercaps actually charge to about 4.4 volts because of the diode drop. The supercaps charge feeds a DC boost convertor. Boost convertor: http://www.ebay.com/itm/3-pcs-XL6009-S...
by henryhanselscott
Wed Mar 25, 2015 9:50 am
Forum: General discussion
Topic: Pi Project Ideas
Replies: 14
Views: 2213

Re: Pi Project Ideas

I have been a Rpi guy since November 2014, just a few short months. I had previously never had any exposure to Linux based computing or Python. I have been an embedded developer for 20 years and primarily have used PIC micros. Now that I can effectively use the Rpi I cannot stop my mind from running...
by henryhanselscott
Tue Mar 24, 2015 9:30 am
Forum: General discussion
Topic: Rpi2 as CNC controller?
Replies: 2
Views: 1209

Rpi2 as CNC controller?

I currently use Mach3 and a Windows box for my CNC equipment. Stepper motion is controlled via pulses out of the parallel port. I have used this setup for several years now and MOST of the time it works good. However, Windows is still Windows. Considering the faster pi2, does anyone who has experien...
by henryhanselscott
Mon Mar 23, 2015 5:00 pm
Forum: General discussion
Topic: Help! Screwed up
Replies: 3
Views: 528

Help! Screwed up

Ok, did something really dumb and cannot figure out how to fix. Using the latest rasbian image I have created a python script that uses tkinter as a GUI. Tkinter is configured to cover the entire screen (no toolbar). The pi is configured to boot straight to the desktop and then the python project st...
by henryhanselscott
Wed Mar 18, 2015 2:21 pm
Forum: General discussion
Topic: pi to pi ethernet data
Replies: 1
Views: 387

pi to pi ethernet data

Curious how I would send data from one pi to another pi using the ethernet port. For example, I want to send the value 245 from one pi to the another pi. Using serial UART from one pi to the other (Using Python3 one each pi) I can easily send this data. But, how would I send this data over ethernet ...

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