topic Re: DECIMAL NUMBER ARITHMATIC in S12 / MagniV Microcontrollers

DECIMAL NUMBER ARITHMATIC

tballer — Fri, 04 Jul 2008 03:45:42 GMT

I am new to this and am trying to do arithmetic on a decimal number in the following format:
XXX.XXXXXX

The arithmetic will include squaring, taking the square root, dividing and addition and subtraction. What is the best way to go about this?

Re: DECIMAL NUMBER ARITHMATIC

JimDon — Fri, 04 Jul 2008 03:48:17 GMT

Depends on what you consider "best".

The easiest way it to use doubles.

Re: DECIMAL NUMBER ARITHMATIC

tballer — Fri, 04 Jul 2008 05:18:26 GMT

Is it easy then to square a number, lets say 128.3434434, and put it in memory in a 16 bit microcontroller?

Re: DECIMAL NUMBER ARITHMATIC

JimDon — Fri, 04 Jul 2008 09:16:17 GMT

You will need to learn the "C" programming language, but yes it is.

Re: DECIMAL NUMBER ARITHMATIC

nikosxan — Sat, 05 Jul 2008 14:40:06 GMT

Using a C compiler for the specific MCU you use will enable you to have variables of float types and supportes also math (multiplication / division / root, even some trigonometry). Also when having variables and a C language enviroment is no problme 'store results' in memory.... However all these ends up with a lot of code size increase, since float math nedds a lot of code to be implemented, but this should be no major problem if you have decent FLASH memory (eg 64 K or more...). Also, MCUs support integer math internally and up to multiplication / division, so doing a sqrt or a sine is also time consuming compared to sipler 8 / 16 bits math.

What's the need for doing such math ?

Re: DECIMAL NUMBER ARITHMATIC

nikosxan — Sat, 05 Jul 2008 14:43:06 GMT

...Cont...

If you really need do complex math (as float numbers support, sin / cosine, sqrt etc) the only way to go is use a high level language (mostly C for microcontroller, but also Basic or even pascal could be found)...