SparkFun Forums

[Guilherme]

Hi, somebody here knows about a FFT routine for MSP430 that works?

Or do you know if it is possible to create one using a MSP430?

[Guilherme]

I found one application note related with the hardware multiplier, but the example is written in Assembly language. Is there any way to convert to C language?

And in the MSP430x2xx datasheet written this:

"The hardware multiplier is
implemented in some MSP430x2xx devices."

How could I know if my device has hardware multiplier? I have a MSP430F2012.

[OldCow]

If you use c. The compiler and linker will take care of you. You do not need to know if there is a hardware multiplier or not. Just have faith. You are not allowed to know right from wrong. (Otherwise you are a sinner. )

[leon_heller]

A quick way to find out if the device has a hardware multiplier is to write an assembler program using it and see what happens when you assemble it.

Leon

[Guilherme]

I have this transfer function:

Gc(s)= Kc.s³/(s+129.4)²+(s+76655)²

and I would like to implement a digital filter using a MSP430F2274 (32Kb+256B de Flash / 1Kb de RAM).

And after the signal pass through the filter, I would like to calculate the Vrms from the signal.

If this is possible, can somebody explain to me the way that I could do? For example:

"You should use the A/D and your algorithm should have this and this..."

Tks a lot

[marcovansteen]

Maybe google + the following hints will help:

Use a FIR architecture for the filter with as few coefficients as possible.
Choose ADC sample rate high enough (>> 25 kS/s).

Probably, deriving its coefficients using 'frequency sampling' method is the easiest way: calculate values of Gc(f) for several f, do inverse FFT, this gives you the impulse response h(n) of the filter. All this you can do in Excel (fourier function).

Now simulate the frequency response of the real h[n] with the finite number of coefficients and with the limited resolution (can again be done in excel). Tune the coefficients to optimize the response.

Vrms calculation is done by summing the squares of a number of samples. Take care of scaling..

(I see that most digital filter design software provide no options for random frequency transfers so these are of limited use here. However matlab (or maybe scilab) could be useful)

hope this helps.. good luck...

[falingtrea]

Here is the TI selector guide link for MPS430 devices with a Hardware Multiplier:

HWM MPS430