AM62L: Booting issue when RGB-Display is connected.

According to Hardware Design Considerations for Custom Board Design Using AM62L (AM62L32, AM62L31) Processor Family in section 2.2 Configuring the Boot Mode and AM62L (AM62L32, AM62L31) Processor Family Schematic, Design Guidelines, Design Checklist and Review Checklist in section 6.1.5 Configuration of Boot Modes (for Processor):

"The recommendation is to connect the processor boot mode input pins (configured for alternate function) to the alternate function through a 0Ω series resistor. Series resistor can be used to isolate the alternate function during testing."

Using resistors with any appreciable resistance value (e.g., 33Ω, 47Ω, or 100Ω typical termination values) on the BOOTMODE[15:12] pins creates a voltage divider effect between the pull-up/pull-down boot configuration resistors and the load presented by the RGB display circuitry. This corrupts the logic level seen at the boot mode pins during POR, causing the device to sample an incorrect boot mode configuration.

Without the RGB display connected, the muxed lines are only loaded by the boot mode pull-up/pull-down resistors, which correctly establish the desired logic levels. When the display is connected, the additional loading (from the display driver's input impedance or termination) shifts the voltage levels at the BOOTMODE pins, resulting in a misread boot configuration.

What I could recommend you:

• Replace series termination resistors with 0Ω resistors on all BOOTMODE[15:12] pins muxed with RGB signals. The 0Ω option still provides a convenient test point/isolation capability (you can lift the resistor for testing), while not introducing any voltage drop.
• Verify pull resistors on BOOTMODE[15:12] are firmly tied to VDDSHV0 through 10kΩ or 47kΩ resistors (pull-up or pull-down as needed for your target boot mode). These must dominate the logic level at the pin during POR regardless of the connected RGB load.
• For BOOTMODE[11:0] pins muxed with RGB (if any) — since input buffers are OFF during POR in reduced boot mode, these pins are safe and can also use 0Ω series resistors. No pull resistors are required on these since they are not sampled during boot.
• Ensure boot mode inputs are stable before PORz deasserts — any capacitive loading from the display cable/connector must settle before the device samples the boot mode pins.
• You can review these Threads:
  • [FAQ] AM625 / AM623 / AM620-Q1 / AM64x / AM243x / AM62Ax / AM62Px / AM62D-Q1 / AM62L - Bootmode implementation without isolation buffers
  • [FAQ] AM625 / AM623 / AM620-Q1 / AM64x / AM243x / AM62Ax / AM62Px / AM62D-Q1 / AM62L - Supported bootmode configurations

Best Regards,

Borislav Lazarkov