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 for OSPI or QSPI
memory interface
- Connection of attached device IO supply and the fixed-voltage IO supply for IO group
referenced to (powered by) the OSPI0 interface signals (connected to the same supply
source)
- IO level compatibility (1.8V) between processor and attached device.
- Mapping of processor pin (ball number) to the required functionality (peripheral, signal
name) on custom board (selected pin supports muxing (multiplex) the IO for the required
function) and naming of the signal as per the processor data-sheet pin attributes signal
name column (when using standard peripherals).
- Matching of the polarity of the peripheral data interface signals between the processor
and the attached device (Example Mapping of D0-D7 (data) of processor to D0-D7 of attached
device or similar connections)
- Provision for series resistor near to the processor clock output pin and pulldown for
OSPI0_CLK signal near to the attached memory device
- Provision for pullups including value for OSPI/QSPI data interface and CS signals
- Implementation of attached device reset
logic to support boot and connection of attached device reset input.
- Clock loop back configuration based on the interface selected (OSPI/QSPI) and memory
device used
- Provision for series resistor added on the CS0 that supports boot
- Connection of DQS input from memory (OSPI) and pulldown for the processor DQS input
pin
- Connection of LBCLKO from processor output (for QSPI) to DQS input and addition of
pulldown near to processor DQS input pin
- LBCLKO connection when not used
- Connection recommendations to implement x1 or x2 attached device interface
- Addition of required bulk and high frequency capacitors, and value.
Schematic Review
Follow the below list for the custom schematic
design:
- The recommendation is to compare the OSPI0 or QSPI0 memory interface connections with
EVM 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
schematic implementation.
- Series resistor (0Ω) provision for OSPI0_CLK (close to processor clock output pin for
control of 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 X1 (single) or X2 (multiple) attached devices. Follow
the EVM or recommended guidelines when connecting the OSPI0 interface to multiple
attached devices (more than 1 attached device)
- IO level compatibility between processor and attached device. The attached device IO
supply and the fixed-voltage IO supply for IO group VDDS1 referenced to (powered by) the
OSPI0 interface signals are connected to the same supply source.
- Supply rail connected to the fixed-voltage IO supply for IO group VDDS1 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
using a 2-input (RESETSTATz and processor IO)
ANDing logic or using 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).