SPRUHZ7K August 2015 – April 2024 AM5706 , AM5708 , AM5716 , AM5718 , AM5718-HIREL
By default, the EMIF keeps its SDRAM CS signals high (CSs are active-low). To direct a command to only one of the SDRAMs, EMIF asserts the CS signal (CSN0 or CSN1) to the SDRAM for the duration of the command. If the EMIF_SDRAM_CONFIG[3] EBANK bit is set to 0x0, CSN1 will always be driven high except during initialization and for the Refresh, Power-Down and Self-Refresh commands.
The EMIF always performs burst accesses to the SDRAM. Multiple SDRAM bursts may need to service a single local burst request. Table 15-73 through Table 15-75 show a few examples how EMIF performs SDRAM accesses for a linear incrementing transaction type. T0, T1, etc. are clock cycles. R0 is read starting at column 0, R8 is read starting at column 8, and R16 is read starting at column 16. D0-1 is the data from column 0 and 1, D2-3 is the data from column 2 and 3, and so on.
| T0 | T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10 | T11 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| R0 | R8 | ||||||||||
| D0-1 | D2-3 | D4-5 | D6-7 | D8-9 | D10-11 | D12-13 | D14-15 |
| T0 | T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10 | T11 | T12 | T13 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| R4 | R8 | R16 | |||||||||||
| D4-5 | D6-7 | D8-9 | D10-11 | D12-13 | D14-15 | D16-17 | D18-19 | Unused | Unused |
| T0 | T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10 | T11 | T12 | T13 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| R6 | R8 | R16 | |||||||||||
| D6-7 | Unused | D8-9 | D10-11 | D12-13 | D14-15 | D16-17 | D18-19 | D20-21 | Unused |
The EMIF uses the unused data phases in the preceding figures by issuing successive read commands if there are reads to open banks pending in the command FIFO.
The write data conversion from SDR to DDR is done outside the EMIF.