AM5728: UART0 garbage characters

ashok sihag

Part Number: AM5728

Hi,

I am using UART0 as boot mode for AM5728.I am not getting CCCCC....CHARACTER.Instead of that i am getting garbage value.Baud rate is 1152000.

Please guide.

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

TI__Guru**** 393215 points

Hi,

On AM57x devices the default boot UART is UART3, not UART0. See section 33.3.5 in the AM572x TRM Rev. L for details.

0 ashok sihag over 6 years ago in reply to Biser Gatchev-XID

Intellectual 380 points

Hi,

Yeah you are right.Actually by mistake i wrote UART0.Actually i am looking at UART3.I am getting garbage value on that port.

What can be the cause of that?

0 Biser Gatchev-XID over 6 years ago in reply to ashok sihag

TI__Guru**** 393215 points

AM57x devices do not print "C" characters at boot time. They send out an ASIC ID. The UART boot procedure is different. See discussion here: e2e.ti.com/.../1888053

0 ashok sihag over 6 years ago in reply to Biser Gatchev-XID

Intellectual 380 points

Hi,

Thanks for the input.I am also getting the character "VA!.."continuously.So what is the next step to proceed.

0 Andreas Dannenberg over 6 years ago in reply to ashok sihag

TI__Guru 70392 points

Ashok,

ashok sihag said:
Thanks for the input.I am also getting the character "VA!.."continuously.So what is the next step to proceed.

So you getting this out of UART3? With no code running?

Can you try adding a pull-up resistor to your logic-level UART output signal of the device?

Sometimes floating pins can cause random data to be seen by an external receiver, especially when no user code is running yet (that would take care of pinmux etc. initialization). Temporarily adding a pull-up resistor would help making sure that this is not the case here.

Regards, Andreas

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AM5728: UART0 garbage characters