Cortex-M3 vs Cortex-M4

[karthik chandra]

In my project im interfacing pulse sensor, GSR sensor, BP sensor and some medical related sensor. Can any one help me which processor to choose(Cortex-M3 or Cortex-M4).
i bought LPC1768(Cortex-M3)
Cortex-M4 core’s capability for DSP.
im interfacing many analog sensors should i go for Cortex-m4
And also i dint get these sentences There is also the option to get a single precision floating point unit (FPU) on a Cortex-M4. If your application requires floating point math, you will get this done considerably faster on a Cortex-M4 than you will on a Cortex-M3.can you please explain me

 

[memarian]

In my project im interfacing pulse sensor, GSR sensor, BP sensor and some medical related sensor. Can any one help me which processor to choose(Cortex-M3 or Cortex-M4).
i bought LPC1768(Cortex-M3)
Cortex-M4 core’s capability for DSP.
im interfacing many analog sensors should i go for Cortex-m4
And also i dint get these sentences There is also the option to get a single precision floating point unit (FPU) on a Cortex-M4. If your application requires floating point math, you will get this done considerably faster on a Cortex-M4 than you will on a Cortex-M3.can you please explain me

Hi,

It's actually depends on your project and what you need to do with the Data and final target price. ( Cortex-M3 usually costs less than Cortex-M4 - Highly depends on manufacturer and chip capability)

The Cortex-M4 chips usually have a FPU Unit. If you need floating point processing a lot, this unit can accelerate that a lot. for example multiplying 2 Single precision variables in FPU takes 1 clock cycle, but without FPU it can take up to 14 clocks (if i remember correctly). if you need Floating Point Divide operation that ratio will be more!

BTW, Some of the Cortex-M4 Processors have Data and Instruction Cache , so they will be even faster than Cortex-M4 without cache (at Same clock) specially if you have many branches (if/then/else ,...) in your program.

 

[karthik chandra]

thanks for the quick reply
in my project im adding signals(only one sensor) and taking mean and ill be comparing with later signals with that mean
rest sensors ill be comparing with threshold

Cortex-M3 is enough or should i go with Cortex-M4

 

[memarian]

thanks for the quick reply
in my project im adding signals(only one sensor) and taking mean and ill be comparing with later signals with that mean
rest sensors ill be comparing with threshold

Cortex-M3 is enough or should i go with Cortex-M4

Hi,

according to your application and assuming that your sensor sampling rate is reasonable , it seems that you should be ok with Cortex-M3, but it highly depends on number of sensors, sensor sample rate, any other interface /connection management and most important factor is your Cortex-M3 MCU Clock.