SPRUHZ7K August 2015 – April 2024 AM5706 , AM5708 , AM5716 , AM5718 , AM5718-HIREL
This section applies only to SR2.x.
The internal pull resistors of pads gpmc_a[27:24, 22:19] can be permanently disabled by pulling sysboot15 low during power-on-reset deassertion. When sysboot15 = 0, the corresponding PULLUDENABLE bit does not apply anymore. In this case it is a don't care bit whatever value set. This functionality is intended to be used when mmc2_dat* signals are configured on the gpmc_a[27:24, 22:19] pads. In this case, if sysboot15 = 0, external pull-up resistors with values as per JEDEC eMMC specification (JESD84-B451) must be connected to these pads. If gpmc_a[27:24, 22:19] are connected to non-multiplexed NOR flash used for booting and sysboot15 = 0, external pull-down resistors are mandatory on these pads otherwise boot is not possible. During NOR flash run-time accesses the external pull-down resistors are not needed.