General

Review and verify the following for the custom schematic design:

1. Above sections, including relevant application notes and FAQ links.
2. Pin attributes, signal description, and electrical specifications.
3. Electrical characteristics, timing parameters, and any additional available information.
4. MMC0 interface is compliant with the JEDEC eMMC electrical standard v5.1 (JESD84-B51)
5. AM62x and AM62Ax processor families implements a soft PHY. The pulls required for DAT0, clock, and control signals are recommended to be implemented externally.
6. Include a series resistor (0Ω) on MMC0_CLK placed as close to processor clock output pin as possible to dampen reflections. MMC0_CLK is looped back internally on read transactions, and the resistor eliminates possible signal reflections, which cause false clock transitions. Use 0Ω initially and adjust as required to match the PCB trace impedance.
7. Add pullups (10kΩ or 47kΩ) for DAT0 and CMD signals. Connect the pullup to the IO supply group VDDSHV4 (MMC IO rail). For DAT1-7 eMMC device is expected to have the pullups enabled during reset. The eMMC host/PHY disables the eMMC device pullups and enables processor internal pullups. Provision for external pullups is optional, or delete the pullups.
8. VDDSHV4 (1.8V or 3.3V) and the attached eMMC device IO supply is required to be powered from the same power source.
9. Add a pulldown (10kΩ) to the eMMC attached device clock input near to the attached device.
10. For implementing eMMC device reset, use a 2 input ANDing logic when the memory is used for boot. Connect RESETSTATz as one of the inputs and processor IO as another input. Add a pullup for the processor IO input near the AND gate input pin and an isolation resistor near to the processor IO output. Alternatively, RESETSTATz is used as the reset source. When RESETSTATz is used as the reset source, verify the voltage level compatibility with the eMMC IO supply. Use a level shifter as required.
11. When eMMC boot is not required, the eMMC attached device reset can be controlled by the processor IO. The recommendation is to pulldown the reset of the eMMC memory device during board power reset.
12. Add additional decoupling capacitors for attached memory device as required. Refer SK-AM62P-LP schematics.

Schematic Review

Follow the below list for the custom schematic design:

1. Required bulk and decoupling capacitors are provided for processor and attached device rails. Compare with the SK schematics
2. Pull values for the data, command, and clock signals. Compare with the relevant SK
3. Series resistor value and placement on the clock output signal near to the processor clock output
4. Implementation of reset logic including the IO level compatibility. Adding a capacitor at the reset input of eMMC attached device is not recommended when RESETSTATz or processor IO is connected directly to control the reset. A stand-alone reset connection to reset the eMMC memory device is not recommended
5. Supply rails connected follow the ROC

Additional

1. Connect an external pulldown on CLK, and external pullups on CMD and DAT0 to prevent the eMMC device inputs from floating until software initializes the host controller and processor IOs associated with MMC0. The eMMC standard mandates that eMMC devices have internal pullups enabled during reset on DAT1-7, external pullups are not required for DAT1-7 signals. Software turns on the respective internal DAT pullups when the bus width is increased from 1-bit mode to 4-bit or 8-bit mode. External pulls are required because the IOs associated with MMC0 are implemented with standard dual-voltage LVCMOS IO cells with the capability of multiplexing additional signal functions to the respective device pins. MMC0 IOs buffers are off during reset as it is not known what interface may be connected to MMC0 pins
2. Verify eMMC_RSTn reset input is enabled in the eMMC device (eMMC non-volatile configuration space) for the reset logic to be functional. The GPIO reset option makes it possible for software to reset the attached device (eMMC, OSPI, SD card, OLDI, or EPHY) without resetting the entire processor if there is a case where the peripheral becomes unresponsive. Eliminate the GPIO option and use the reset output, either warm or cold. Software forces a warm reset if the peripheral becomes unresponsive. However, using warm reset resets the entire device, rather than trying to recover the specific peripheral without resetting the entire device. When RESETSTATz is used to reset the attached device, verify the IO voltage level of the attached device matches the RESETSTATz IO voltage level. A level translator is recommended to match the IO voltage level. Alternatively, use a resistor divider and select an optimum impedance value. A slow rise or fall time of the eMMC reset input causes too much delay. Low reset input causes the processor to source too much steady-state current during normal operation.
3. ANDing logic additionally performs level translation. Verify the reset IO level compatibility before optimizing the reset ANDing logic. IO level mismatch can cause supply leakage and affect processor operation
4. Pulldown is selected for eMMC, SD card or other peripherals since there are cases where the clock is stopped or paused in a low logic state and the pulldown option is consistent with the logic state.