I.MX28 Custom HW hangs at power initialization

[joelk]

I am having trouble bringing up my custom board based on the i.MX28 EVK. I have inserted print functions in the boot code to see where it fails. I'm using sb_loader to boot from USB. it hangs after PowerPrep_Init4p2Regulator(); line 725 in power_prep.c

My hardware follows the VDD5V only setup as outlined in AN4199

We have unmarked NO_DCDC_BATT_SOURCE and marked out NO_VDD_SOURCE in power_prep.c

Question 1: Are there other code changes that I need to make to support VDD5V only configuration?

Question 2: I notice that I have left the TESTMODE pin C10 floating. Is this a likely cause of the hang? I have marked this line to be tied low for the next PCB revision.

Attached are my power_prep.c and hardware checklist

Any help is greatly appreciated.

Original Attachment has been moved to: power_prep.c.txt.zip

[igorpadykov · Accepted solution]

Hi Joel

you are right TESTMODE should  be tied to ground, otherwise

chip can enter to test mode.

You can further add debug printf for locating accurate operand:

this would be brownout cause and then you can add time delay or

increase brownout level.

All necessary patches are given below

Updates and Patches (9)

i.MX28 Evaluation Kit|Freescale

Best regards

igor

[joelk]

We had our local assembly shop modify the PCB to tie Testmode low before placing the BGA. Our boards now get all the way through power initialization without any problem. I still am not able to boot all the way to uboot prompt but I will start a new thread because it is a RAM problem now.

Thank you for the help

[joelk]

Hi Igor, thanks for your reply.

We have already applied the patches. I will try adjusting the brownout level.

How can i tell if the chip has entered test mode? Is there an obvious change in the chips behavior that I can watch for to make sure this isn't happening?

[igorpadykov]

Hi Joel

sorry details about test mode are not available,

this mode is only for factory testing.

~igor