35.5.3 Refresh (Auto-Refresh Command)

An Auto-refresh command is used to refresh the external SDRAM devices. Refresh addresses are generated internally by the DDR-SDRAM device and incremented automatically after each auto-refresh. The MPDDRC generates these auto-refresh commands periodically. A timer is loaded in the MPDDRC_RTR with the value which indicates the number of clock cycles between refresh cycles (see MPDDRC Refresh Timer Register). When the MPDDRC initiates a refresh of the DDR-SDRAM device, internal memory accesses are not delayed. However, if the CPU tries to access the DDR-SDRAM device, the client indicates that the device is busy. A refresh request does not interrupt a burst transfer in progress.