Electronic Notebook

egayam · Joined: 02 Jun 2009 Posts: 5

I need help for my proposal electronic notebook.

This project accepts inputs by write or draw anything in the 4 wire resistive touchscreen, and then the user can save or load the inputs to or from MMC card.

Anyone can give me sample circuits in interfacing touch screen and PIC 16F877A?

email me at ichategay@gmail.com.

Thank you.

Rohit de Sa · Joined: 09 Nov 2007 Posts: 282 Location: India

Use Google for the interface schematics. I found quite a few sites. Here's one:
http://www.circuitcellar.com/library/print/0100/dahlin-114/2.htm

Also have a look at http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3402
This is a resistive touchscreen controller from MAXIM IC. It cost me around USD 8 here in India. Interfacing was breeze.

Rohit

Ttelmah · Guest

Seriously though, to 'write', with handwriting recognition, requires a lot more computer 'grunt' than a PIC, and to just do it as pictorial storage (simpler), requires a lot more RAM than any but the largest PIC's. Certainly not an 877....

Best Wishes

Rohit de Sa · Joined: 09 Nov 2007 Posts: 282 Location: India

A 'do-able' solution would be to have an external RAM chip, with bit in the RAM mapping to 'pixels' or 'dots' on the touchscreen (naturally, without an LCD or some other kind of display behind the touchscreen, you wouldn't be able to see any dots/pixels. Every time a point on the screen is tapped with a stylus, the corresponding RAM location could change to a 1. Obviously, the number of pixels on your screen would be restricted by RAM size. For a given screen, the lesser the RAM, the lesser the number of pixels (which implies that each pixel has much larger dimensions; with this scheme a square or rectangular 'area' of the screen becomes into a pixel).

When the user is done with filling in a 'page' of data, he could press a button, which would save the entire RAM contents to the MMC, thus storing things pictorially, as suggested by Ttelmah.

Ttelmah is very right in pointing out that handwriting recognition requires much more computational power - one the lines of a PIC32 or an ARM or TI DSP. With a large touchscreen, even a dsPIC would struggle with real time recognition. Page-wise recognition may be possible with a dsPIC, though. An '877 is sorely out of its league here :-| , except for, maybe proof-of-concept testing.

Rohit

egayam · Joined: 02 Jun 2009 Posts: 5

Thank you for your advice and suggestions

Steve H · Guest

You may want to try the Beagleboard - it is a small form factor PC that appears to have the capability that you want.

http://beagleboard.org

Lots of support and videos.

HTH - Steve H.

egayam · Joined: 02 Jun 2009 Posts: 5

egayam · Joined: 02 Jun 2009 Posts: 5

rberek · Joined: 10 Jan 2005 Posts: 207 Location: Ottawa, Canada

I think this would be even worse. Its one time programmable and has less RAM and program memory than the 877. And fewer IO too.

r.b.

dyeatman · Joined: 06 Sep 2003 Posts: 1933 Location: Norman, OK

What compiler are you using? You are asking for code over in the MikroElectronica forum as well.

You really need to heed the advice and stop looking at the 16 series PIC! As mentioned earlier, if you plan to do writing or even print recognition a 16 series chip is NOT going to do it. You need to move away from the PIC to something a bit more powerful if you are going to do anything more than take the pixels and save them to a memory card. Regardless, none of the 16 series PICs is a good choice.

It's a lofty ambition to want to tackle handwriting recognition but, as a beginner, you are getting in over your head. This kind of thing is a very complicated project. For the last 20 years I have had the privilege of working with and programming some of the most advanced handwriting and character recognition software in the world. Some of our programs take more than TWO HOURS to compile on a quad core processor!

Good Luck!
_________________
Google and Forum Search are some of your best tools!!!!

egayam · Joined: 02 Jun 2009 Posts: 5

arunb · Joined: 08 Sep 2003 Posts: 492 Location: India

Here are several alternatives .....

1. If handwriting recognition is not required, then the 18F series may do the job. Another alternative is the PIC24 series, and then there is the PIC32 also

2. Use a touchscreen phone such as HTC. This comes installed with Windows Mobile, all you have to do is develop the handwriting recognition software. No need to fiddle around with hardware, programmers etc.

thanks
arunb

PS: Do you really need the handwriting recognition feature ?? , if you can skip this feature, you might be able to solve half the problem