The DDR subsystem in this device comprises DDR
controller, DDR PHY and wrapper logic to integrate these blocks in the device. The DDR
subsystem is referred to as DDRSS0 and is used to provide an interface to external SDRAM
devices which can be utilized for storing program or data. DDRSS0 is accessed via CBASS0
interconnect.
Table 9-1 shows DDRSS allocation across device domains.
Table 9-1 DDRSS Allocation Across Device DomainsInstance | Domain |
---|
MCU | MAIN |
---|
DDRSS0 | - | ✓ |
Figure 9-1 shows an overview of the DDRSS0 and its surrounding modules.
The DDRSS0 supports:
- Memory Types:
- DDR4 up to 1600Mbps
- LPDDR4 up to 1600Mbps
- Memory Bus Features:
- 16-bit width with in-line ECC
- Up to 2 ranks
- SDRAM address range up to 8 GB
- System Bus Interface:
- 128-bit data width
- Little endian only
- Address aliasing prevention to block accesses to unpopulated SDRAM region
- Clock asynchronous to DDR clock
- Configuration Bus Interface:
- 32-bit data width
- Linear incrementing addressing mode
- 32-bit aligned accesses only
- Little endian only
- Clock asynchronous to DDR clock
- Key Features:
- Full coherency across all commands
- Bank interleaving
- Priority based scheduling
- Scheduling based on bank openness
- Class of Service (CoS) - Three latency classes supported
- Read/write scheduling to avoid turn-around time
- Prioritized refresh scheduling
- Dynamic change of refresh rate via software for extended temperatures
- Statistical counters for performance management
- SDRAM ECC Features:
- In-line ECC
- 32-byte ECC calculated over 256-byte data
- Read-modify-write ECC for sub-word writes
- Support ECC cache to improve in-line ECC performance
- Support 64 cache-lines each 512-byte wide
- ECC address error logging
- Statistical counters for counting ECC errors
- Low Power Features:
- All power modes defined by JEDEC
(clock stop for LPDDR4, self-refresh, power-down, etc.)
- Self-refresh entry and exit via software or
hardware clock stop request/acknowledge
- System bus clock stop via hardware clock stop request/acknowledge when controller is idle
- Automatic idle power saving mode when no or low activity is detected
- DDR and system bus clock frequency change using self-refresh via software or hardware clock stop request/acknowledge
- Turning off SoC power after DDR is put into self-refresh (DDR reset and CKE I/O retention)
- Tri-stating of all DDR I/O cells via software
while driving CKE and RESETn pins during self-refresh
- LPDDR4 Frequency Set Point (FSP)
- Functional Safety Features:
- VBUSM2AXI bridge AXI bus timeout
- DDR PHY Features:
- Automatic and software controllable initialization and calibration (ZQ) for the DDR PHY and I/O cells
- Automatic and software controllable delay line calibrations with Voltage and Temperature (VT) compensation
- Automatic and software controllable write levelling with VT compensation
- Automatic read DQS gate training per rank with VT compensation
- Automatic and software controllable DQ/DQS eye training per rank
- Automatic and software controllable read and write data bit deskew
- Automatic and software controllable Command/Address (CA) levelling with VT compensation for LPDDR4
- Automatic and software controllable CA bit deskew for LPDDR4
- Refreshes to SDRAM during leveling and training
- No seeding requirement based on board topology for any of the leveling and training algorithms
- Dynamic/automatic I/O Receiver disable when read transfer is not on going
- Capability of disabling data macros and I/O cells when not in use