CE/FCC fails if CLK frequency is increased (higher than 48MHz)

We plan to buy 200pcs J1010 (reComputer from Seeed) but this version comes with 16GB eMMC. Because eMMC is a no go for us for many reasons and the main one being the space.

We asked if microsd slot can be added and we’ve been told that they are going to release a version with microsd slot along with eMMC but the CLK frequency for sdcard is going to be limited to 48MHz due to EC/FCC. We verified that the Jetson nano 4GB Developer Kit has an SDR104 SDXC UHS card with CLK set to 208MHz and passed EC/FCC tests.

Could somebody clarify this for me ? We would like the same speeds for sd card as Jetson Nano Developer Kit has. What would be your advice here? Thank you!

Hi, this needs your board vendor to clarify. Please check with them directly.

Hi @konkhra , this is Elaine from Seeed. We tested for higher CLK and it will fail for CE/FCC. We followed the strict certification requirement so the default frequency is SDR25.
In perspective of the frequency you need, you can adjust to SDR-50/ SDR-104 for higher speed, but it will cause failure of CE/FCC.

Do you have a guideline on how to modify the CLK frequency? I’m trying to figure out if this modification is an easy change or creates headaches.

Also I was expecting more clarification on why the Jetson Nano 4GB Developer Kit with CLK frequency set to 208MHz passed CE/FCC. My guess would be the lack of eMMC on the developer kit.

We are thinking about developing our custom carrier board. Can you point me to the EC/FCC guidelines so that we can assure we pass those tests?

Hi @konkhra this is Eddy form Seeed. We’ll publish this guideline when the carrier board with SD slot is ok. If necessary, you can directly contact our technical support mailbox.

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