General
Review and verify the
following for the custom schematic design:
- Reviewed
above "Common checklist for all
sections" section of the user's guide.
- Required
memory interface configuration and recommended
connections.
- IO level
compatibility between processor and attached device.
Connection of attached device IO supply and the IO
supply for IO group referenced to (powered by) the
OSPI0 interface signals.
- Provision
for series resistor and pulldown for OSPI0_CLK.
- Provision
for pullups for data and control signals.
- IO level
compatibility between processor and attached
device.
- Implementation of reset logic and connection of
attached device reset input.
- Clock
loop back configuration based on the memory device
and interface selected (OSPI/QSPI).
- Connection of DQS input from memory (QSPI) or
LBCLKO from processor (QSPI).
Schematic
Review
Follow the below list for
the custom schematic design:
- The
recommendation is to compare the OSPI0 or QSPI0
memory interface with EVM or SK schematic
implementation for provisioning of parallel pulls,
series resistors, and the resistor values.
- The
recommendation is to compare implementation of
attached device reset logic with the EVM or SK
schematic implementation.
- Series
resistor (0Ω) provision for OSPI0_CLK (close to
processor clock output pin to control possible
signal reflections) and external pulldown (10kΩ) for
OSPI0_CLK (close to attached device clock input pin)
to hold the attached device in low state (there are
cases where the clock is stopped or paused in a low
logic state and the pulldown option is consistent
with this logic state).
- Provision
for pullups (10kΩ or 47kΩ) are provided for data and
control signals that can float (to prevent the
attached device inputs from floating until driven by
the host). The recommendation is to verify the
supply source connected to the pullups.
- Connecting the OSPI0 interface to multiple attached
devices (more than x1 attached device) is not
recommended or allowed.
- IO level
compatibility between processor and attached device.
The attached device IO supply and the IO supply for
IO group VDDSHV4 referenced to (powered by) the
OSPI0 interface signals are connected to the same
supply source.
- Supply
rail connected to the IO supply for IO group VDDSHV4
referenced to (powered by) OSPI0 peripheral and
attached device IO supply follows the ROC.
- Implementation of external loopback (based on the
use case).
- Connection of DQS from OSPI memory device and
pulldown added for DQS input near to processor.
- Connection of OSPI0_LBCLKO for QSPI memory device
through 0Ω.
- Pulling
up the reset input to a high state during reset or
supply ramp (is not recommended).
- Implementation of reset logic when used for boot.
The recommendation is to implement the attached
device (OSPI/QSPI memory) reset using a 2-input
ANDing logic. Processor GPIO is connected as one of
the input to the AND gate with provision for pullup
(10kΩ or 47kΩ) (to support boot) near to the ANDing
logic AND gate input and provision for 0Ω to isolate
the GPIO output for testing or debug. The other
input to the AND gate is the MAIN domain warm reset
status output (RESETSTATz).
- When
OSPI0 interface is not used for boot, the reset
logic can be implemented using a processor IO. A
pulldown is recommended near to the reset
input.
Additional
- The
recommendation is to verify that the OSPI/QSPI/SPI Board
Design and Layout Guidelines section of the
processor-specific data sheet is followed.
- In case OSPI/QSPI
boot mode is implemented, the recommendation is to verify
the silicon errata, selected memory meets the boot criteria
described in the processor-specific TRM (or verify with TI,
recommend using E2E).