[sdiy] ARM vs dsPIC performance

[Eric Brombaugh]

On Sep 13, 2006, at 9:43 PM, Robin Whittle wrote:

> I wonder how the ARM microcontrollers compare with the latest dsPIC
> microcontrollers for execution speed.
> <snip>
> Without doing a lot of research, it is my impression that a 40 MIPs
> dsPIC, programmed in assembler, would be faster than this 60 MHz ARM
> chip, for general 16 bit DSP operations.
>

I'd tend to agree with you - especially for true DSP operations. The 
autoincrement and prefetching capabilities built into the dsPIC allow 
MACs to run at the full instruction speed - you'll never get that kind 
of throughput on a generic ARM processor. The dsPIC instruction set is 
fairly orthogonal, so it's not too hard to pick up the essentials 
quickly. ARM can do 32-bit operations but execution time is lame. dsPIC 
works best on 16-bit data but does so very quickly.

Development tools-wise the ARM's got it all over the dsPIC. ARM is 
ubiquitous - supported by many semiconductor manufacturers and 
development systems. dsPIC is single-source and hasn't gotten nearly as 
much market penetration. I've got no experience with the dsPIC C 
compiler, but ARM is supported by gcc that's an excellent compiler with 
a deep history - many commercial ARM IDEs use gcc in the backend.

I guess it boils down to what you're after: for complex applications 
that don't demand DSP or tight time constraints I'd consider ARM. For 
simple stuff or situations that need medium-precision DSP the dsPIC is 
a great choice.

Eric