MSP430F2616: Math function required more cycle

Rohit6230

Part Number: MSP430F2616

I am adding following math function in my code pwr(), exp(), log() using math.h file, but controller take lots of time to solved equation.

Can you tell me how to increase controller speed. with example.

Also I am trying to add IQmathLib.h file by adding file through linker and write down command like

float ftemp32,

float var1 = 4.678,

ftemp32 = _IQexp( var1 )

compiler compile successfuly but ftem32 output is always display 0,

over 4 years ago

0 Keith Barkley over 4 years ago

Guru 35580 points

You have to convert your float to an IQ32 before doing an operation on it.

IQ32 is *not* a float format, it is a fixed point format.

0 Rohit6230 over 4 years ago in reply to Keith Barkley

Intellectual 705 points

Hi keith, can you explain with example. Also do I need to convert my float value into hex format if my var1 is not constant or not defined...

0 Keith Barkley over 4 years ago in reply to Rohit6230

Guru 35580 points

Sorry, I don't have any examples handy. I have no idea what you mean by "not constant or not defined".

0 Wei.Jetim Zhao over 4 years ago in reply to Rohit6230

TI__Genius 13215 points

Hi,

I would suggest you to go through the package of the IQmath library, which have the user's guide document and examples.

0 Wei.Jetim Zhao over 4 years ago in reply to Rohit6230

TI__Genius 13215 points

Hi,

I haven’t heard from you for more than a week, so I’m assuming you were able to resolve your issue. If this isn’t the case, please click the "This did NOT resolve my issue" button and reply to this thread with more information. If this thread locks, please click the "Ask a related question" button and in the new thread describe the current status of your issue and any additional details you may have to assist us in helping to solve your issues.

0 Rohit6230 over 4 years ago in reply to Wei.Jetim Zhao

Intellectual 705 points

I want to find out log of float value after every 1 sec but when I am using log( float x) , then current take 3-4 sec for calculating od log value. and whenever I am using _IQlog (float x ) then output is always zero..

Can you help me how to calculation log faster.

0 Keith Barkley over 4 years ago in reply to Rohit6230

Guru 35580 points

3-4 seconds? What is your clock speed?

Assuming your values are bounded you can always use a lookup table and some interpolation.

0 Rohit6230 over 4 years ago in reply to Keith Barkley

Intellectual 705 points

My clock frequecy is 16 Mhz... I got float value after averaging of adc counts on every second. So every time I got different float value in variable. So i need to calculate that every time and find log value of this

0 Wei.Jetim Zhao over 4 years ago in reply to Rohit6230

TI__Genius 13215 points

Hi Robit,

16MHz is the max processor frequency you could use with the device.

For your "code pwr(), exp(), log() using math.h file", did you use MSPMATHLIB for your device? If yes, I'm afraid the library doesn't support MSP430F2xx devices as described on the page of the library.

For using example about __IQlog, you could get guide on the document and the example below could be your reference as for _Qlog function.

http://dev.ti.com/tirex/explore/node?node=ADU3.dZ2hTsKa37Gphr7aQ__IOGqZri__LATEST

0 Rohit6230 over 4 years ago in reply to Wei.Jetim Zhao

Intellectual 705 points

Hello Wei,

I am using IQmathLib.h library. but my variables are in Float so whenever I am using log function the output display zero.

For example

flaot a,b,c,d;

a= b / c ;

d = _IQlog( a ) ;

in case log value = 0.1265 then d always show 0 becouse of iqlog is in uint32 format.

As I read document that iq is in UINT32 format. How I can proceed for floating calculation.

0 Wei.Jetim Zhao over 4 years ago in reply to Rohit6230

TI__Genius 13215 points

Hi,

Please find how to use the data types and functions in the example I shared you.

You should use data type of _qN(where 1 <= N <= 15) instead of float for _IQlog.

0 Rohit6230 over 4 years ago in reply to Rohit6230

Intellectual 705 points

Hi,

Due to set of whole program optimization level, Controller not processing log function fast. I set that at global optimization and now its calculate log function in millisecond.

Thank you very much for your reply.

0 Wei.Jetim Zhao over 4 years ago in reply to Rohit6230

TI__Genius 13215 points

Hi Rohit,

Thanks for feedback you progress. Please feel free to come back if any further question or issue.

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MSP430F2616: Math function required more cycle