Visible to Intel only — GUID: iga1405375477899
Ixiasoft
Visible to Intel only — GUID: iga1405375477899
Ixiasoft
33.2.2.4. Sharing Pins with other Avalon® memory-mapped interface Tri-State Devices
If an Avalon® memory-mapped interface tri-state bridge is present, the SDRAM controller core can share pins with the existing tri-state bridge. In this case, the core’s addr, dq (data) and dqm (byte-enable) pins are shared with other devices connected to the Avalon® memory-mapped interface tri-state bridge. This feature conserves I/O pins, which is valuable in systems that have multiple external memory chips (for example, flash, SRAM, and SDRAM), but too few pins to dedicate to the SDRAM chip. See Performance Considerations section for details about how pin sharing affects performance.
The SDRAM addresses must connect all address bits regardless of the size of the word so that the low-order address bits on the tri-state bridge align with the low-order address bits on the memory device. The Avalon® memory-mapped interface tristate address signal always presents a byte address. It is not possible to drop A0 of the tri-state bridge for memories when the smallest access size is 16 bits or A0-A1 of the tri-state bridge when the smallest access size is 32 bits.