topic SDK to enable 8ch DMIC Board for RT685-AUD-EVK in i.MX RT Crossover MCUs

SDK to enable 8ch DMIC Board for RT685-AUD-EVK

Hthornburgh — Fri, 11 Nov 2022 00:09:26 GMT

I was trying to find an SDK provided by NXP to get my 8 CH DMIC board setup with the RT685-AUD-EVK. I imagine NXP should have something ready to go since they sell these two devices. If anyone could point me in the right direction that would be greatly appreciated. Thanks!

Re: SDK to enable 8ch DMIC Board for RT685-AUD-EVK

xiangjun_rong — Fri, 11 Nov 2022 10:57:02 GMT

Hi,

There is DMIC driver example as the screenshot for i.mxrt600 family, pls try to use it.

Hope it can help you

XiangJun Rong

Re: SDK to enable 8ch DMIC Board for RT685-AUD-EVK

Hthornburgh — Fri, 11 Nov 2022 18:15:13 GMT

Thank you. The instructions in the read_me have instructions for the MIMXRT685-EVK and include moving resistors and resoldering. Has anyone utilized this SDK for the AUD-EVK? I don't want to follow instructions for the wrong board and find out that I shouldn't have moved them...

Re: SDK to enable 8ch DMIC Board for RT685-AUD-EVK

xiangjun_rong — Wed, 16 Nov 2022 06:12:01 GMT

Hi,

Unfortunately, there is not example based on AUD-EVK, all examples are based on MIMXRT685-EVK. Because the pins are multiplexed with multiple function, the resistors are used to switch the function. So do not care about the resistor, only check if the pins are connected to the DMIC device.

Hope it can help you

XiangJun Rong

Re: SDK to enable 8ch DMIC Board for RT685-AUD-EVK

Hthornburgh — Fri, 18 Nov 2022 19:40:54 GMT

Thank you I was able to listen to the mics with the DMIC driver example. My next goal is to be able to bring the 8 channels of dmic into my computer, I think a combination of the dmic_multi_channel with usb_device_composite_audio_multi_ch would be effective. Do you have any guidance on how to merge these two sdk's? @xiangjun_rong

Re: SDK to enable 8ch DMIC Board for RT685-AUD-EVK

Hthornburgh — Fri, 18 Nov 2022 19:44:32 GMT

@xiangjun_rong thank you I was successful in listening to the 8ch DMIC board with this SDK. My next goal is to get the 8 channels into my computer via usb. I think a combination of the DMIC_Multi_Ch and USB_Device_Composite_Audio_Multi_Ch would be effective, do you have any guidance on how to combine these two sdk's? Or is there already one available that does this that I am overlooking?

Re: SDK to enable 8ch DMIC Board for RT685-AUD-EVK

xiangjun_rong — Tue, 22 Nov 2022 03:31:58 GMT

Hi,

I think it is okay to put the PCM samples from multiple DMIC to the USB load, because both the DMIC and USB are stream, pay attention to the synchronization problem.

XiangJun Rong

Re: SDK to enable 8ch DMIC Board for RT685-AUD-EVK

mlkezarev — Tue, 13 Jan 2026 05:41:32 GMT

Hi,

I’m trying to run the dmic_multi_channel CM33 demo on EVK-MIMXRT685 with the 8-DMIC array board.

Per the demo documentation, enabling the 8-DMIC board on J31 requires moving several resistors (e.g. R379, R380, R384, R389, R390, R391, R392 to 2–3). After doing this, FlexSPI Octal Flash (U19) becomes inaccessible:
- LinkServer flashing fails
- ROM ISP (blhost) connects, but FLEX-SPI-NOR shows Sector Size = 0 / Page Size = 0
- Flash erase/write is impossible

My questions:
Is this demo expected to run without Octal Flash (RAM-only workflow)?
Is there an official flashing/boot procedure after the resistor changes?
Are all resistor changes required, or can some remain in the default state to keep FlexSPI flash working?
Right now it looks like the required DMIC hardware setup prevents normal flash programming/boot.

Thanks for any guidance.