calculator

[nano]

hi all....im a new member...and im working on a calculator project... i wonder if i needed any help in my project would anyone help me or guide me to any useful source about this topic.

 

[blueroomelectronics]

What microcontroller do you plan to use?

 

[HarveyH42]

You would need to be much more specific on what your assignment is. I don't think many people have even considered building a calculator, considering they are pretty easy to pick up for a few dollars most anywhere. They are also handed out for free as advertising. I've got quite a few I never use over the years, banks, insurance office, tax preparer... Hardly worth the time, effort, and money. Usually people build their own to either improve on what's available, or to save money. Since there are many sources of free calculators, that leaves only to improve on something.

 

[nano]

hi thanx alot im gonna use "16f84A" microcontroller

 

[nano]

well im a student and im taking embeded lab this semester....i didn't start making this project yet...but if i faced any kind of problem while maken it.... i will be asking u again for any help ... and thanx anyway

 

[Nigel Goodwin]

hi thanx alot im gonna use "16f84A" microcontroller

Well the 16F84a was obselete last century, I would suggets you use a more modern device, which will be cheaper, and better specified.

 

[HarveyH42]

Well the 16F84a was obsolete last century, I would suggets you use a more modern device, which will be cheaper, and better specified.

But I found an already completed project on the web, that uses the 16F84a. Should be an easy 'A'...

 

[Nigel Goodwin]

But I found an already completed project on the web, that uses the 16F84a. Should be an easy 'A'...

Or an 'F' for cheating

At least move it to a different PIC so it's not blindingly obvious

 

[HarveyH42]

I was only kidding. Wonder if the instructor gets a lot of clones turned in, since I would expect there are many people doing this, other than for school. Really not a bad assignment, read a keypad input, LCD/LED display, and the program to pull it all together, in a small amount of memory (don't know the capacity, wouldn't expect much).

 

[nano]

hi, im having a problem with the multiplication code....
the calculator is supposed to deal with decimal numbers... and multiplying two 8-bit no's the result will be saved in two registers... the problem is after storing the result in( rh& rl) how to convert the number as one number and in decimal so that it could be displayed on the lcd using MPLAB...

 

[lasielle]

nano, you haven't specified any of the design brief you have to work to so anything I say must be a guess... If you are required to work in decimal, the most common method of representing numbers in most commercial calculators is some form of BinaryCodedDecimal - four bits represent 0-9, you store two decimal numbers per byte, and perform your calculations in decimal, just like you do with pen and paper. It isn't as fast as true binary maths, but you don't have to do any conversions for input or display, and any micro will do the BCD calculations far faster than any human can. Many types of calculations are faster done by using look up tables and interpolation rather than complex algorithms. I suggest you go and search for vintage calculator sites, particularly TI and HP. They often have details about how commercial calculators worked internally. I've seen some very detailed info including old patents on calculation methods used in famous historical calculators. Try some of the vintage calculator forums, some guys there know a lot about calculation methods. Good luck, Colin