66AK2L06: What do the reserved bits mean in DEVSTAT register?

Jason Hsui

Part Number: 66AK2L06

Hi, all,

As the follow link shows:

e2e.ti.com/.../2253607

I still work on the secondary arm boot issue on our board.

We are using 66AK2L06 on our board which doesn't have dedicated FPGA and MCU to control booting sequence as EVM.

But we have checked it meets the power supply and booting sequence requirement with datasheet.

I have tested TI EVM with TCI6630K2 and 66AK2L06(replaced manually). There isn't any problem on EVM.

I notice that the reserved DEVSTAT bits value are different between our board and EVM.

The value on our board is 0x12408087 while it is 0x02008087 on EVM(bit22 is different).

I think bit22 in DEVSTAT may reflect what is the unmet conditions to 66AK2L06 on our board.

Does anybody know what is the reserved bits in DEVSTAT register mean?

Any help will be appreciated.

Best Regards,
Jason

0 Yordan Kovachev over 9 years ago

Hi Jason,

I've notified the factory team. Their feedback will be posted here.

Best Regards,
Yordan

0 db_woodall over 9 years ago

Hello,

The Reserved bits are for internal (TI) use only. They have no application for end users.

-dave

0 Jason Hsui over 9 years ago in reply to db_woodall

Hi, Dave,

I am not want to use the reserved bits in my application.

From the datasheet, bit24-bit20 indicates the bootstrap value latched via the external pins.

I suspect that we maybe connect some pin(s) incorrectly which cause the secondary arm cores failed to boot up.

I just want to know which pin the bit22 corresponds to.

Best Regards,

Jason

0 db_woodall over 9 years ago in reply to Jason Hsui

Hi Jason,

The reserved bits do not necessarily map to pins. They may map to internal conditions.
-dave

0 Jason Hsui over 9 years ago in reply to db_woodall

I have found what the root cause with secondary arm failed to boot up.

Some power supply requirements are more strict as show in datasheet.

And when the secondary arm boot up, the bit22 in DEVSTAT is cleared as expected.

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