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Dumping registers on SD clock line of i.MX6 solo EVK

Question asked by 麻生 淳一 on Jan 23, 2019
Latest reply on Jan 28, 2019 by igorpadykov


I am looking at the schematic of IMX6SOLOX_SABRESDB-DESIGNFILES then noticed there are 10 Ω dumping resistors on each SD clock lines(R53, R94 and R83).

When R83 on SD4_CLK were replaced with 0 Ω resistor, I obserbed the SD card could not work with SD4 ports.

The below is the picture of SD4_CLK with 0 Ω resistor on i.MX6 side, there is a spike on the rising edge.

But the there is no spike on the SD4_CLK on SD card side. (see below)


In case of R83 with 33 Ω resistor,  SD card works.

Then I have some questions.


What are the purpose of those resistors and why are those needed?


Dose the spike on SD4_clock affect the data sampling for receiving data from the SD card?