5.4 External gating of the SRAM interface

The SMC has a partial Q-Channel device interface. An external device can use the Q-Channel interface to gate transactions on the SRAM interface.

The external gating Q-Channel interface moves the SMC to a state that forcefully stops all activities towards the SRAM, when ext_gt_qreqn goes LOW. The SMC cannot deny an external gating request.

The SMC accepts an external gating request when there is no ongoing transfer and its internal buffers are empty. After the SMC sets ext_gt_qacceptn LOW, the system can apply the reset without the risk of data loss.

If the SMC receives a new AXI transaction while ext_gt_qreqn and ext_gt_qacceptn are LOW (Q_STOPPED state), then the cfg_gate_resp signal controls whether the SMC:

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