SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
By default, the EMIF keeps its SDRAM CS signal high. To direct a command to only one of the SDRAMs, EMIF asserts its CS signal to the SDRAM for the duration of the command.
The EMIF always performs burst accesses to the SDRAM. Multiple SDRAM bursts may need to service a single local burst request. Table 17-79 through Table 17-82 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 | T14 | T15 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| R2 | R4 | R8 | R16 | ||||||||||||
| D2-3 | Unused | D4-5 | D6-7 | D8-9 | D10-11 | D12-13 | D14-15 | D16-17 | Unused | Unused | Unused |
| 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.