Waveform of SD Card data and Clock line

[sadatanvashisth]

I am using imx6UL ,in my design i have a SD card slot connected over usdhc2. Functionally the SD card is working fine but when I am probing the SD card data line and Clock line there is a overshoot up to 3.8 V for 2ns and undershoot of 1V for 2ns in Data line and in clock signal waveform is swinging between -1V to 4V.

What could be the reason. Will it be harmful for the processor.

Wave forms attached for your reference.

[igorpadykov]

Hi sadatan

reason may be layout of sd signals, please check layout recommendations

in sect.3.5.2 High speed signal routing recommendations Hardware Development

Guide for the i.MX 6UltraLite Applications Processor
https://www.nxp.com/docs/en/user-guide/IMX6ULLHDG.pdf

>Will it be harmful for the processor.

please check allowed signal levels provided in sect.4.6.2 I/O (GPIO) DC parameters

i.MX6UL Datasheet http://www.nxp.com/docs/en/data-sheet/IMX6ULCEC.pdf

Best regards
igor
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[sadatanvashisth]

Thanks for the reply Igor.

I have checked the details and found that the overshoots are higher than what the maximum limit is and then I have cross checked the waveforms on the NXP evaluation board as well for SD card and found similar kind of over shoot and undershoot where with approximately swing between -1V to 4V. Can you please verify the same on the evaluation board MCIMX6UL-EVK and confirm. Is it really an issue?