Question about using VIT library on RT1170-EVK

[Shawn_]

Hello everyone,

I‘m recently learning to use the VIT library for wake-up word recognition on RT1170-EVK. As described in the VIT documentation, the VIT library supports 3 microphones, but since RT1170-EVK does not have proper MIC placement, only one SAI-EM6022 MIC is enabled in the SDK Demo. My question is if I want to use the VIT library on RT1170-EVK and enable 2 MICs, what changes do I need to do in hardware? Can I use the SAI-EM6022-MIC as the reference MIC and then use a DMIC on the EVK as MIC2 to enable the AFE in the VIT library?

Thanks and Regards!

[kerryzhou · Accepted solution]

Hi @Shawn_ ,

  Thank you for your interest in the NXP MIMXRT product, I would like to provide service for you.

   The RT1170-EVK and the SDK with VIT:

SDK_2_11_0_MIMXRT1170-EVK\boards\evkmimxrt1170\audio_examples\maestro_record

It is using the on board SAI-EM6022 MIC, and it just use 1 channel in the VIT, you can check the vit_proc.c:

#define NUMBER_OF_CHANNELS _1CHAN

typedef enum { _1CHAN = 1, _2CHAN, _3CHAN} NumberOfChannel_en;

If you want to use more MIC, you may consider to use the on board DMIC, with will trigger by the PDM, it will collect the data to PCM, then you an connect the PCM data to the VIT input cannel.

This is the thought, we still don't have the related code.

But, as I know, if you want to add more MIC channel, modify the vit_proc.c

Wish it helps you!

If you still have questions about it, please kindly let me know.

Best Regards,

Kerry

[Shawn_]

Hi Kerry,

thanks for your anwser. I still have a question, as it is mentioned in VIT's document, the recommended distance between 2 microphones is 3.5cm to 7cm. But the RT1170-EVK has no proper placement. So if I want to use the VIT Library for 3 DMIC just in the same way as it is described in the following documenthttps://www.nxp.com.cn/webapp/Download?colCode=TP-CONNECTS2021-ENT445&location=null ,what should I do on the EVK, or maybe it is unpossible for EVK, I need to connect another 2 DMICs additional outside the EVK?

Thanks and Regards!

[kerryzhou]

Hi @Shawn_ ,

  Thanks for your updated information and effort.

  Your mentioned point is reasonable, so we can consider the RT1170-EVK other DMIC is not very good for the VIT to add more MIC.

   Maybe you need to add external MIC which meet  :the recommended distance between 2 microphones is 3.5cm to 7cm.

  It may consider the different mic interference issues.

Wish it helps you!

Best Regards,

kerry