Embedded Memory User Guide: Agilex™ 5 FPGAs and SoCs

ID 813901
Date 9/03/2024
Public
Document Table of Contents

2.3. Asynchronous Clear and Synchronous Clear

The Agilex™ 5 M20K and MLAB embedded memory blocks support asynchronous clear and synchronous clear on output latches and output registers.
  • Asynchronous Clear (aclr): This signal clears the memory block output immediately when asserted. The output remains cleared until the next read cycle after the aclr signal deasserts.
  • Synchronous Clear (sclr): This signal clears the memory block output on the next rising edge of the output clock after the sclr signal is asserted. Similar to aclr, the output stays cleared until the next read cycle after the sclr signal deasserts.
Note: The M20K blocks support asynchronous clear on the read address registers, but this functionality is limited to simple dual-port and simple quad-port modes only. When the read address registers are cleared in the M20K block, the subsequent reads will access the memory content at address 0.
Important: Separate Signals for Different Configurations: Both aclr and sclr signals are independent and must be used separately for each memory block configuration. You cannot combine them for a single clearing operation.
Figure 5. Behavior of Asynchronous Clear and Synchronous Clear in Registered ModeThe figure below depicts how asynchronous clear (aclr) and synchronous clear (sclr) signals affect the output data of Agilex™ 5 embedded memory blocks when operating in registered mode. Registered mode refers to a configuration where the outport is registered. All the registered output ports are synchronous to the output clock.
Figure 6. Behavior for Asynchronous Clear and Synchronous Clear in Unregistered ModeThe figure below depicts how asynchronous clear (aclr) and synchronous clear (sclr) signals affect the output data of Agilex™ 5 embedded memory blocks when operating in unregistered mode. Unregistered mode refers to a configuration where the outport is not registered. All the unregistered output ports are not synchronous to the output clock.
Figure 7. Behavior When Asynchronous Clear is Used on Read Address Register in Registered and Unregistered ModesThe figure below depicts how asynchronous clear (aclr) impacts the output data of Agilex™ 5 embedded memory blocks when used on the read address register operating in registered and unregistered mode.