AM6411: AM6411 UART Port cannot output

Hello,

• Verify the boot‑mode pins
  • Make sure the BOOTMODE[15:0] pins are latched correctly for UART boot. Please review the AM64x Technical Reference Manual section 4.3 Boot Mode Pins.
  • After changing the boot‑mode setting, power‑cycle the device or assert a warm reset so the ROM samples the new value.
• Identify which UART the ROM uses for UART boot
  • On AM64x devices the ROM UART bootloader uses UART0 in the MAIN domain. Please review the AM64x TRM section 4.4.8 UART Boot.
  • Ensure that the UART0 TX/RX pins are connected to your debug adapter and that they are not muxed to other functions.
• Check pin multiplexing and I/O settings
  • Confirm that the UART0 pins are set to their UART function (not GPIO, SPI, etc.).
  • Verify the correct I/O voltage (1.8 V or 3.3 V) matches your transceiver/level‑shifter.
  • Look for any accidental pull‑up/pull‑down that could inhibit the signal.
• Hardware connections
  • TX of the AM6411 should go to RX of your adapter, and RX to TX (crossed).
  • Ensure a solid ground connection between the board and the adapter.
  • If you use a level‑shifter, verify it is oriented correctly and powered.
• Baud rate and serial‑port settings
  • The ROM UART bootloader communicates at 115200 baud, 8‑N‑1 by default.
  • Set your terminal program to 115200 baud, 8 data bits, no parity, 1 stop bit, no flow control.
• Clock and power
  • Make sure the MAIN domain (including UART0) is powered and its clock is enabled. The ROM enables the necessary clocks during boot, but a missing power‑on reset or a faulty power rail can prevent the UART from functioning.
• Software/image considerations
  • If you are flashing a secondary bootloader (e.g., U‑BOOT, SBL) via UART, ensure that the image is correctly formatted for UART boot.
  • If you later switch to QSPI boot for normal operation, verify that the secondary bootloader’s UART console is configured for the same UART instance and baud rate you are probing.
• Debug with an oscilloscope/logic analyzer
  • Probe the UART0_TX pin (and optionally UART0_RX) to see if the ROM is transmitting any data (even a garbage pattern indicates activity).
  • No transitions at all suggest the UART is not enabled or the pins are muxed away.
• Review the Errata document
  • Please review the AM64x Errata i2371 Boot: ROM code may hang in UART boot mode during data transfer
  • If you use UART as a backup boot, please review i2415 Boot: UART Backup Boot Authentication Failure w/ xSPI Primary Boot Mode.

Best Regards,

Borislav Lazarkov

Borislav,

Due to FQE asks customer to submit ticket as well, customer submit this ticket.

please check below TI interal ticket, I already discussed with sreenivasa. It's the same issue. you can check below ticket first.

 AM6411: uart0 no output but PCIE is ok and failure rate is 7 pcs of ic in 15Ku 

BR,

frank

Hello Frank,

Thank you for the information.

Should I close this thread and to proceed the topic in the thread you have sent me?

Best Regards,

Borislav Lazarkov 

Borislav,

I am ok to follow up with internal ticket. due to this is public, i cannot share customer's information. So, not sure what we can discuss here.

BR,

frank