17.2 Embedded Characteristics

  • Interface to DDR2, DDR3, LPDDR2, LPDDR3 Memories
  • All Signals Supported on Control, Write Data and Read Data Interfaces
  • Internal 5 AXI Ports Controller with Arbitration
  • External 16-bit DDR Interface
  • Support for 1 Memory Rank
  • For DDR3, LPDDR2 and LPDDR3 Configurations: Direct Software Request Control or Programmable Internal Control for ZQ Short Calibration Cycles
  • For DDR3, LPDDR2 and LPDDR3 Configurations: Support for ZQ Long Calibration after Self-refresh Exit
  • For LPDDR2 and LPDDR3 Configurations: Support for ZQ Reset Feature through Software
  • Dynamic Scheduling to Optimize Bandwidth and Latency
  • Read and Write Buffers in Fully Associative CAMs (Content Addressable Memories)
  • Delayed Writes for Optimum Performance on SDRAM Data Bus
  • Software-programmable Quality of Service (QoS) Support
  • Control Options to Avoid Starvation of Lower Priorities
  • Coherency for Write-After-Read (WAR) and Read-After-Write (RAW) Hazards
  • Paging Policy Selectable by Configuration Registers:
    • Leave pages open after accesses, or
    • Close page when no further accesses are available in the controller for that page, or
    • Auto-precharge with each access, with an optimization for Page Close mode which leaves the page open after a flush for read-write and write-read collision cases
  • Supports Automatic DDR-SDRAM Power-down Entry and Exit caused by Lack of Incoming Transaction for a Programmable Time
  • Supports Automatic Clock Stop (LPDDR2/LPDDR3) Entry and Exit caused by Lack of Incoming Transaction
  • Supports Automatic UDDRC Low-power Mode Operation caused by Lack of Transaction Arrival for a Programmable Time through the Hardware Low-power Interface
  • Supports Self-refresh Entry and Exit as follows:
    • Support for automatic self-refresh entry and exit caused by lack of incoming transaction for a programmable time
    • Support for self-refresh entry and exit under software control
    • Support for self-refresh entry and exit using dedicated DDRC hardware low-power interface control
  • Support for Dynamically Changing Clock Frequency while in Self-refresh:
    • DDR3 DLL-off mode supported
    • Shadow timing registers provided to allow fast frequency changing
  • Support for Deep Power-down Entry and Exit under Software Control (LPDDR2/LPDDR3)
  • Support for explicit SDRAM Mode Register Updates under Software Control
  • Flexible Address Mapper Logic to allow Application-specific Mapping of Row, Column, Bank, and Rank Bits
  • Programmable Support for 1T or 2T Timing
  • User-selectable Refresh Control Options:
    • Controller-generated auto-refreshes at programmable average intervals
    • Ability to disable controller-generated auto-refreshes
    • Ability to issue a refresh through direct software request
    • When LPDDR2/LPDDR3 is used, user-selectable ability to perform per-bank refreshes rather than all-banks refreshes
  • Advanced Power-saving Design Includes No Unnecessary Toggling of Command, Address, and Data Pins (RAS/CAS/WE/BA/A hold last state after each command; DDR_D does not transition on writes when bytes are disabled)
  • Support for DDR2, DDR3, DDR3L, LPDDR2, LPDDR3
  • Leverages Out-of-order Requests to Maximize Throughout
  • The UDDRC Implements the Following Standards:
    • JEDEC DDR2 SDRAM Specification, JESD79-2
    • JEDEC DDR3 SDRAM Specification, JESD79-3
    • JEDEC DDR3L SDRAM Specification, JESD79-3-1A
    • JEDEC LPDDR2 SDRAM Specification, JESD209-2
    • JEDEC LPDDR3 SDRAM Specification, JESD209-3