How to implement SinC filtering of Sigma Delta data stream with G4 peripheral and FMAC?

[Dldw.1]

I am preparing to replace TMS320F280049C of Ti Company with STM32G474. The sampling of motor current in the project is based on Sigma /Delta modulator. How to use FMAC and other peripheral devices provided by G474 to realize sinC filtering and decoding of code stream?

best regards to you 。

​

[GwenoleB]

Hello @Dldw.1​ 

Is there a specific reason you selected STM32G4?

My first proposition should be to use CMSIS DSP and design a sinC FIR filter. Getting your data from SPI with DMA channel to sample them through your software FIR.

Have a look on STM32L4 which embeds the DFSDM block (AN4990). The sinC filter is already implemented.

I hope it help. Do not hesitate to ask for further information.

Best Regards,

Gwénolé

[Dldw.1]

Thank Gwenole for your reply。

We choose TO use STM32G4 in this servo motor control project, mainly because real-time response is very critical in motor control algorithm. The Cordic unit inside STM32G4 is very suitable for coordinate transformation (sin and cos functions), as well as the square root operation in motor algorithm. In addition, The built-in filter FMAC is suitable for IIR operations (Notch). It has the advantage of low cost. If sigma-Delta bit stream modulation can be implemented on STM32G4, it is undoubtedly a very competitive scheme.

​

Best regards to you.

​

[Asantos]

I would suggest using the STM32H723VE or the STM32H730 if a 128Kb flash is enough. It has DFSDM, FMAC, CORDIC, double-precision FPU, 520MHZ, cortex-m7, and costs almost the same as the STM32G4 (for the same memory and pinout size)

[Dldw.1]

Hi Asantos, 

Thank you for your suggestion. I will try to see if the chip supply and price are suitable 

Best regards to you.