iMX6SL UART debug issue.

[yakovshaulov]

Hi,

I've a custom board based iMX6SL. One of the serial ports (UART1), for debugging, connects directly to a header, in a way to connect external UART to USB adapter. Our SW Engineer tried to debug through this port and has encountered a problem.

He sent bit stream from PC to our board (I can see the bit stream on the scope on RX line) but the board doesn't respond at all. i.e., we don't see any changes on the TX line from the iMX6SL, and it should happen. 

As I understood, there is no any SW issue because, as SW engineer claims, he took the exactly code for debug on iMX6SL. So, probably is a HW problem.

On the other side, we do able to read and write to LPDDR through the USB port, and seems like the handshake between the LPDDR to iMX works properly. 

Anyone have meet same problem?

Do I miss something and what could be the problem? Is it HW or SW isuue?

[yakovshaulov]

Can anyone explain to me what could be the problem?

[igorpadykov]

could you elaborate what do you mean saying

"MFG tool does not report any problem but the U-Boot does not send any

data out to the UART and does not respond to any command," ?

[igorpadykov]

Hi Yakov

what response is expected from board, is some program running on processor

and expecting data from uart ? One can attach jtag debugger and check

UARTx_URXD, UARTx_USR2 (RDR ready bit), also enable uart

clocks in CCM_CCGRn. Had valid uart baudrate programmed and

selection of register IOMUXC_UART1_UART_RX_DATA_SELECT_INPUT made.

Best regards
igor
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[yakovshaulov]

We are using IMX6SL EVK BSP

We are trying to load U-Boot into RAM using MFG tool.

MFG tool does not report any problem but the U-Boot does not send any data out to the UART and does not respond to any command, even if we stop the MFG before jumping to the kernel, and instead U-Boot is called.

We didn't change any UART configuration but it should work on UART 1

So we expected to see any U-Boot promt.