SDR SDRAM Controller August 2002, ver. 1.1 1 M-WP-SDR-1.1 Introduction The single data rate (SDR) synchronous dynamic random access memory (SDRAM) controller provides a simplified interface to industry standard SDR SDRAM. The SDR SDRAM Controller is available in either Verilog HDL or VHDL and is optimized for the Altera® APEX™ architecture. The SDR SDRAM Controller supports the following features: ■ Burst lengths of 1, 2, 4, or 8 data words ■ CAS latency of 2 or 3 clock cycles ■ 16-bit programmable refresh counter used for automatic refresh ■ 2-chip selects for SDRAM devices ■ Supports the NOP, READA, WRITEA, AUTO_REFRESH, PRECHARGE, ACTIVATE, BURST_STOP, and LOAD_MR commands ■ Support for full-page mode operation ■ Data mask line for write operations ■ PLL to increase system performance ■ Support for data-path widths of 16, 32, and 64 bits Figure 1 shows a system-level diagram of the SDR SDRAM Controller.