imx6q boot up failed with serial downloader mode or internal boot on new sabresd based custom board

[raymondwang]

Dear all, we design new iMX6Q board based on sabresd prototype. But we encountered boot up failure issue.

1. MX6Q Design is based on MMPF0100F0+MX6Q ;
2. All power rails are checked properly and as expected;
3. 24MHz and 32kHz clock sources both work;
4. BOOT_MODE1 and BOOT_MODE0 default is set at 10 which should be internal boot mode;

  Connect usb cable to PC ,since it's raw board it should populate USB HID device on PC. Unfortunately,we see nothing on PC;

  We tried to change BOOT_MODE cfg to 01 (serial downloader mode), Nothing happened on PC;

  We change BOOT_MODE cfg to 00 ,HID device populated on PC and MFG tool can flash eMMC device without error. But after resumed to 10 BOOT_MODE, my board can't boot up.

   My question is,Why in serial downloader or internal boot mode ,no HID device populated on PC;

   What other check list we missed? Please help!

[raymondwang]

Anybody can help us?

[VladanJovanovic · Accepted solution]

What is the value of EIM_EB3 ping (BOOT_CFG4[7]) at startup? If it's pulled high, I believe internal ROM will go to loop and not do anything in internal boot and serial downloader modes. This is documented in Table 8-2 in ref. manual.

[raymondwang]

Thank you!, You are right, we had double checked BOOT_CFGx and found BOOT_CFG4[7] is pulled up. Now it's fixed.

[Rita_Wang]

Hi raymond,

It's strange.In the newest reference manual, the boot mode pin setting is show in below picture. As you config BOOT_MODE  00 it worded, when changed to others it did not. So you'd better check the SD card, eMMC and other devices.

Best Regards

Dan