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Hello
I am using LPC1768 for a motor control application. The motor will be controlled with a series of pulses each of 2us wide.
I use a asin function to calculate the time between two pulses. (The motor moves clock and anti-clock wise, hence a sin function is considered)
when asin function is called, the code tends to break. ie it gets stuck at hardware handler routine.
I believe the issue is with the use of asin function, although i am not sure about it. I am using inbuilt asin in math.h
Can anyone kindly suggest me how to use a asin function on LPC1768. If anyone can provide me a small code for how to use it on LPC1768 would be of great help.
I have tried the code on rowley crossworks and on Keil. Both seem to give the same error. But in simulator asin function is working fine.
Kindly suggest.
Regards
Prakash
HELLO
We are also precalculating all the values and storing it in a table and then reading the calculated values from there.
But the issue is that the code seems to work well with the simulator while it gives problem when i try to run using JTAG.
This issue, i believe is because of asin function. When this function is called the system hangs in hardfault handler.
When is just give asin(1) and try using debugger. The system moves to hardfault handler.
I am also thinking of not using math.h and rather writing asin function. Is it possible to get the asin function definition. It would be very helpful if someone can provide the same. May be it would work
Do you maybe give a number of invalid range to asin()?
Note that floating point takes a lot of room - both in code space, and extra stack space.
I recommend building the table on a PC. Either use a small C program or Excel. Just add the table as const data in the source code, and your program will be ready to run directly after boot.
And having the table printed and visible makes it easier for you when debugging. Besides - you can't get any runtime errors from the creation when it's already created ;)
No I have given valid number only in asin function ie from -1 to 1.
Its not feasible to generate the look table from PC, because in my project the look table will change in run time according to input given.
Change in what way? Most often, you can get away with a single lookup table that is just a multiplier from the real value and the real-time code can perform some simple integer arithmetic.