AM5716: UART boot

vamshi krishna gajjela

Part Number: AM5716
Other Parts Discussed in Thread: SN74LVC2G241

Dear Team,

We have custom board designed based on AM571x IDK, we prefer to boot from UART, but we do not have SN74LVC2G241 on the board. Is this mandatory to boot from UART?

I am using FTD-I cable for USB-UART conversion.

Please help at the earliest.

Thanks.

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

TI__Guru**** 393215 points

This buffer prevents external voltages being present on the UART pins while the processor is unpowered. This can damage the device.

0 vamshi krishna gajjela over 6 years ago in reply to Biser Gatchev-XID

Expert 1695 points

Hi Biser,

Thanks for your response.

We are trying to boot from UART, but we do not see any data from AM571x over UART (Like CCC). How to confirm CPU is running. We are bringing up our custom board.

Please help me what points to check for.

0 vamshi krishna gajjela over 6 years ago in reply to vamshi krishna gajjela

Expert 1695 points

Hi Biser,

Can we use the below boot-mode "Recovery/Upgrade" for UART boot

Thanks

0 Biser Gatchev-XID over 6 years ago in reply to vamshi krishna gajjela

TI__Guru**** 393215 points

UART boot on AM57x devices is different. Please check this thread: e2e.ti.com/.../1888053

0 vamshi krishna gajjela over 6 years ago in reply to Biser Gatchev-XID

Expert 1695 points

Hi Biser,

First concern is I am not getting any messages from UART on power-up ?

0 Biser Gatchev-XID over 6 years ago in reply to vamshi krishna gajjela

TI__Guru**** 393215 points

As I already posted, UART boot on AM57x devices is different. There are no "CCCC..." characters. If you did read the thread I gave above, you probably found this document, which explains the step-by-step UART boot procedure: e2e.ti.com/.../5342.AM57_5F00_UART_5F00_Boot_5F00_SOP_5F00_By_5F00_TI_5F00_Rio_5F00_Final.pdf

0 vamshi krishna gajjela over 6 years ago in reply to Biser Gatchev-XID

Expert 1695 points

Hi Biser,

I understand uart boot is different on AM57X CPU variant and I went through the PPT you shared. Thank you.

On power up, if CPU configured for UART boot it has to transmit ASCI ID, this confirms CPU is running and Boot ROM is ready to accept images. In my case on the custom board with UART boot mode I do not see any messages coming from Boot ROM. What could be the reason?

AM57X transmit ASCI ID on power up in UART boot mode. Is this statement correct with any variant of AM57X?

Please provide pointers for debugging.

0 Biser Gatchev-XID over 6 years ago in reply to vamshi krishna gajjela

TI__Guru**** 393215 points

You most probably will not see anything on the console, the ASIC ID is binary and very short.

There is an important consideration, which I posted initially: "This buffer prevents external voltages being present on the UART pins while the processor is unpowered. This can damage the device." This means that if you connect the FTDI cable before the processor is powered, and the FTDI cable outputs any voltage to the RX/TX lines at this time, most likely the UART I/O cells are damaged. I/O Cells are NOT Fail-safe compliant and should not be externally driven in absence of their I/O supply.

Anyway, I suggest you follow the PPT and see what happens.

0 vamshi krishna gajjela over 6 years ago in reply to Biser Gatchev-XID

Expert 1695 points

Hi Biser,

Thanks for inputs. if I/O cells were damaged still voltage on these pins is 3.3v? Any info on this.

0 Biser Gatchev-XID over 6 years ago in reply to vamshi krishna gajjela

TI__Guru**** 393215 points

I cannot say. You can boot from some other source and check.

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AM5716: UART boot