AM3352: EMU[1:0] questions

Kien

Part Number: AM3352

Hi champs,

I am aware of the Advisory 1.0.36 EMU0 and EMU1: Terminals Must be Pulled High Before ICEPick Samples in the erratasheet.

According to the datasheet, at reset, these 2 pins are H (High-impedance with an active pullup resistor). I have several questions as below.

1. If I need to use EMU0:1 pins as General Purpose Output during normal operation, do I still have to add pull-up resistors to the design?

2. Do EMU0:1 pins play any roles in the booting? Why do they prevent the processor from booting when I have pull-down resistors connected to them?

3. I currently don't have any pull-up resistors for those pins and the board is able to boot normally. But I am not sure if it will be okay for mass production. Please confirm.

Regards,

Kien

over 5 years ago

0 Biser Gatchev-XID over 5 years ago

TI__Guru**** 393215 points

Hi,

1. Yes, it's recommended to have external 4.7kOhm pullups to VDDSHV6.

2. Yes they do. See section 27.1.2.2.2 in the AM335x TRM Rev. P.

3. Internal pullups are weak and may not be sufficient in certain scenarios.

0 Kien over 5 years ago in reply to Biser Gatchev-XID

TI__Expert 3991 points

Biser,

Thanks a lot for your prompt reply. Just one more question.

Chapter 27 in the TRM is about Debug Subsystem. In my opinion, that is for the case when I have a debugger/emulator connecting to the processor via JTAG interface. How about the case when we just power up/reset the processor without having any debuggers connected, ie. during normal operation?

0 Biser Gatchev-XID over 5 years ago in reply to Kien

TI__Guru**** 393215 points

It doesn't matter whether you have a JTAG connected. EMU[1:0] must both be high for normal boot.

0 Kien over 5 years ago in reply to Biser Gatchev-XID

TI__Expert 3991 points

Thanks for your confirmation. Much appreciated.

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AM3352: EMU[1:0] questions