Chain tool speed

[roscop13]

Hello I'v just ordered a NRF51-DK kit.

I'm looking at the different tool chain. In my application speed is critical 16Mhz is actually bearly enough, so my question is:

-Is there a difference in the execution speed of the same code written : Keil , eclipse GCC, or Mbed?

-I see that the NRF51-DK is actually running at 32Mhz, is this ok to put a 32 Mhz Cristal to a nRF51822??

Thanks

[Nguyen Hoan Hoang]

It's all about how you write your code. Knowing how the compiler generate code and write optimize code would be the latest. One compiler with same setting you can have 2 sets of code with one running faster the the other.

A simple example

a = b / 2;  // Takes many cpu cycles
a = b >> 1; // only 1 cycle

Compiler will not optimize that for you.

There is a good book on writing optimized code.

"C++ Footprint and Performance Optimization" by Rene Alexander & Grahm Bensley. Published by SAMS. ISBN 0-672-31904-7

PS. mBed not recommended for speed.