AnsweredAssumed Answered

LS1012A SDHC1 EMMC problem

Question asked by diao bangxi on Mar 24, 2019
Latest reply on Oct 7, 2019 by haff

Hi NXP Team,


We are designing LS1012A(LS1012AXN7HKA) based custom board and we configure both SDHC interface.

SDHC1 is using for emmc support and SDHC2 is using for emmc too.

Emmc on the second eSDHC controller work normally.But Emmc on the first eSDHC controller does not work normally.


  1. SDHC1_CMD, SDHC1_CLK, SDHC1_DATA[3:0] are connected to the corresponding pins of eMMC; 

  1. SDHC1_CD_B is pulled up to O2VDD with a 10K resistor; SDHC1_WP is pulled down to GND through 1K resistance. SDHC1_VSEL is suspended (the development board is connected to the power chip MC34VR5100A1EP to control the voltage switch of SDHC1 interface power supply VCC_EVDD);

  1. SDHC1 interface power supply VCC_EVDD is always 1.8v.


It could not read and write to the eMMC after cold start, Through measuring the SDHC1 interface related pins in LS1012A with an oscilloscope, it was found that the waveform of the pin of eMMC was abnormal during the abnormal operation, and it could not drive to the low level state. The waveform of SDHC1_CLK pin is intercepted as follows:

But after power on for about 2.5 minutes, the eMMC worked normally. The emmc on the first eSDHC controller can read and write normally


Any pointers are greatly appreciated.

Have a great day,