Can the FMAC implement a decimating FIR filter automatically? (can the yet-to-be released STM32U5 FMAC do this)?

[gregstm]

If I have a signal sampled at 16384/32768Hertz, but I am only interested in frequencies below 2000Hz - can I use the FMAC to automatically produce a buffer of FIR filtered samples at 4096Hz? I think some hardware filter accelerators have a decimation register for specifying the down sample rate.

[Imen.D · Accepted solution]

Hello @Community member​ ,

The down-sampling feature is not included in the current version of the FMAC.

Nevertheless, the FMAC is ideally suited for implementing a low pass decimation filter, the down-sampling can be done by simply discarding samples, for example 3 in every 4 in the case of a decimation by 4.

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Imen

[gregstm]

Yes, you can discard samples not needed, but the FMAC has wasted processing for samples not needed - perhaps this makes little difference to the micro's power consumption. The beauty of an FIR low pass decimation filter is that you only have to process the samples you need - if it saves power you might want to consider the down-sampling option for some future versions of the FMAC.