If you are using the external MCU_PORz signal, do you have the MCU_BYP_POR pulled high? The AM65x/DRA80x component supports the internal POK circuit, which eliminates the need for a reset signal generator. If MCU_BYP_POR is pulled high, an external reset pulse with the proper timing relative to the power sequencing must be generated and connected to the MCU_PORz and PORz pins.
If you are using the internal POK circuit, do you have the MCU_BYP_POR pulled low? If the internal POK circuit is enabled, MCU_PORz and PORz are not needed and may be pulled high. If a reset signal is needed for an external device, the MCU_PORz_OUT or PORz_OUT can be used.
If you are using the internal POK circuit, do you have an external pull-up resistor on MCU_PORz? MCU_PORz should be pulled high if the internal POK circuit is used.
Do you have a pull-down resistor on PORz_OUT and on MCU_PORz_OUT? The MCU_PORz_OUT and PORz_OUT signals can be used to provide the reset to other devices on the board, but they must have individual pull-down resistors. The AM65x/DRA80x does not drive the PORz_OUT and MCU_PORz_OUT until the device has started to boot. A pull-down resistor keeps the PORz_OUT and MCU_PORz_OUT signals low during the initial power sequencing.
If you are using external MCU_PORz and PORz, do you have a reset circuit that generates the proper reset pulse? If an external reset is used, it must meet the requirements for pulse length and must be held low during power sequencing.
Are all control pins held in the proper state until reset is released? The pins used to configure the device must be held in the desired state until after the rising edge of the MCU_PORz. If the internal POK circuit is used, they must be held in the proper state until the rising edge of MCU_PORz_OUT. MCU_PORz_OUT and PORz_OUT must have a pull-down resistor to remain in the proper state until reset is released.
Note:
The E3 version of the EVM does not have the pull-down resistors on MCU_PORz_OUT and PORz_OUT.