Design of the µCalc

[apex]

I saw the µCalc in the Episode 107.
How did you get it that flat?
Did you cut out the pcb for the display?
What kind of battery are you using?
Would like to rebuild it, but don't know how to get power on it.
Or is it just driven with a solar cell?
apex

[Mechatrommer]

IIRC, Dave explained every aspects you mentioned.

[johnboxall]

http://www.calcwatch.com/construction.htm

[EEVblog]

I've explained this in one of my live shows somewhere.
Yes, there is an art to getting it that thin, some careful design considerations.
Two CR2016 batteries that are sandwiched between the top and bottom PCB contacts on the thin top and bottom boards.
Careful LCD selection and mounting in the cutout and matching height components.

Dave.

[apex]

OK.
I think I'm understanding it now,
but in the first moment it looked a bit like black magic to me.
I was thinking of using LiPos but they are mostly to big.
apex

[apex]

Thank you for the blog about it.
I was thinking of putting the LCD into the cutout to save a bit of space there,
but with these DOGM-LCDs its pretty easy.
apex

[frank26080115]

I would love to build my own, it looks like there's a full text input capability and it would be great if the microcontroller could execute MATLAB. Can such a task be accomplished with the current PIC microcontroller?

[FreeThinker]

I've explained this in one of my live shows somewhere.

This highlights one of the problems I've found with the forum & Blogs no search facility.Could this be added easily? Would be a great help now that the forum is getting bigger.

[dengorius]

I've explained this in one of my live shows somewhere.

This highlights one of the problems I've found with the forum & Blogs no search facility.Could this be added easily? Would be a great help now that the forum is getting bigger.

What do you mean no search? There is a search box in the top right corner of the forum and you can find a list of all the vlogs http://www.eevblog.com/episodes

[FreeThinker]

I've explained this in one of my live shows somewhere.

This highlights one of the problems I've found with the forum & Blogs no search facility.Could this be added easily? Would be a great help now that the forum is getting bigger.

What do you mean no search? There is a search box in the top right corner of the forum and you can find a list of all the vlogs http://www.eevblog.com/episodes

Well ok there is a search bar but it is very limited (to the point of being useless) and a more fully featured search is really required.

[tyblu]

http://goo.gl/wt9wl

Google: "uCalc site:eevblog.com"

[EEVblog]

I've explained this in one of my live shows somewhere.

This highlights one of the problems I've found with the forum & Blogs no search facility.Could this be added easily? Would be a great help now that the forum is getting bigger.

If there is a suitable plug-in for Wordpress and SimpleMachines, yes.
If anyone has any pointer then I'll be glad to take a look.

Dave.

[TheDirty]

Well ok there is a search bar but it is very limited (to the point of being useless) and a more fully featured search is really required.

There's a search button on the top left that gives you a more advanced search.  On the toolbar beside HOME, HELP.

Still nothing for the vlogs, though.

[Addidis]

Any Idea when we could purchase one of these bad boys?  This is the perfect calculator, small , scientific, programmable , and it uses PIC which is awesome because thats what I know.  I need a calculator any way this is perfect since its soo much more.
I actually like the quick connect icsp jack on there, perhaps a surface mount part between the boards ? otherwise I would still opt to leave it on.

Did you break out any unused pins? this would actually be a great dev board too.  Even if you just leave pads to solder headers to. This is a great design. I want one.

[tyblu]

If there is a suitable plug-in for Wordpress and SimpleMachines, yes.
If anyone has any pointer then I'll be glad to take a look.

May want to try out the WP plugin "Relevanssi". I use it here: http://trajctrl.tyblu.ca . [Note that the site isn't nearly finished, so stuff the comments. I'm trying to put an old lab book online for future scholastic reference.]

[8086]

Great video! very informative

I'm actually working on a credit card sized data logger right now, so this was very useful. Might have to check out that LCD.

[teedeeus]

David,

Awesome!!!

I am fascinated by the touch keypad you are using on the uCalc.  It looks awesome.  How well does it work?  is it easy to mis-type keys when using it?  Do you have to get your fingers perfectly in the solder-mask circles?  Also, could you give me some pointers on using touch sensors with PICs?  I have noticed that alot of PICs now list "touch" on the pin descriptions, but as I am totally used to arduino and know almost nothing about PICs, where do I start?

-teedeeus

[tyblu]

If you want to use Microchip's stuff, try out one of their touch dev kits:
http://goo.gl/ggBsI

[teedeeus]

If you want to use Microchip's stuff, try out one of their touch dev kits:
http://goo.gl/ggBsI

Thanks for that.  I appreciate it.

-teedeeus

[the_raptor]

Hey Dave you know this video means you have to finish the µCalc right? 

With a dust proof container this would be much more handy for me at uni then the µwatch or carrying a full sized scientific calculator around.

[scrat]

I would love to build my own, it looks like there's a full text input capability and it would be great if the microcontroller could execute MATLAB. Can such a task be accomplished with the current PIC microcontroller?

Of course no, such an MCU can't execute MATLAB! However, one could implement a very simple interpreter emulating some Matlab-like behaviour, but it is not an easy task, limited memory, for example, would be an issue.

[teedeeus]

Dave,

I want the uCalc sooooo bad.  Any chance you would open source your design files and provide the link when it's done?  Any possibility you might make this into a kit?  I do know how to solder surface mount components 

-teedeeus

[mikeselectricstuff]

Hey Dave you know this video means you have to finish the µCalc right? 

Dave, let me guess how this went - lots of enthusiasm to get a nice hardware & mechanical design, built the board, wrote enough SW to test the hardware, but then got bored at the prospect of writing all the software...?
I often get the same thing - I _love_ doing hardware & mechanical design but getting stuck into the software tends to be a far less exciting  prospect... Once I get stuck into it, it's usually OK, but I tend to get very easily distracted into doing  anything else apart from getting started.

I wonder if the answer might be to build a few &  let someone with more software enthusiasm do some software in exchange for splitting the proceeds of sales?

BTW for the detail of connecting the top/bottom battery contact, a small leaf-spring contact  type arrangement would probably be the ideal solution.

Also, instead of gluing together, which is a bit permanant, I wonder if there are some tiny screws you could use, or maybe rivets, which could be drilled out.
Another option may be careful use of hot-melt inside cavities in the inner core spacer , which would allow seperation by applying heat - maybe have some thermal vias in the rear cover to make this simpler.
Or larger holes in the rear, into which the hotmelt is injected while the sandwich is clamped together.

[frank26080115]

Hey Dave you know this video means you have to finish the µCalc right? 

lots of enthusiasm to get a nice hardware & mechanical design, built the board, wrote enough SW to test the hardware, but then got bored at the prospect of writing all the software...?

I have the opposite problem, I breadboard something, and then write (what I think is great) software for it, and then never build a finished "product". Mainly because I'm a poor student who can't afford too much hardware.

Also, instead of gluing together, which is a bit permanant, I wonder if there are some tiny screws you could use, or maybe rivets, which could be drilled out.
Another option may be careful use of hot-melt inside cavities in the inner core spacer , which would allow seperation by applying heat - maybe have some thermal vias in the rear cover to make this simpler.
Or larger holes in the rear, into which the hotmelt is injected while the sandwich is clamped together.

How about using solder? Have copper on the edge and solder the two halves together. This might not last after several reassemblies though.

[David]

Dave - What is the nominal current load when the device is in use? How long a battery life do you expect?