SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
The EMIF controller supports the SDRAM commands described in Table 23-5. Table 23-6 shows the truth table for the SDRAM commands, and an example timing waveform of the PRE command is shown in Figure 23-3. EM1A[10] is pulled low in this example to deactivate only the bank specified by the EM1BA pins.
Command | Function |
---|---|
PRE | Precharge. Depending on the value of EM1A[10], the PRE command either deactivates the open row in all banks (EM1A[10] = 1) or only the bank specified by the EM1BA[1:0] pins (EM1A[10] = 0). |
ACTV | Activate. The ACTV command activates the selected row in a particular bank for the current access. |
READ | Read. The READ command outputs the starting column address and signals the SDRAM to begin the burst read operation. Address EM1A[10] is always pulled low to avoid auto precharge. This allows for better bank interleaving performance. |
WRT | Write. The WRT command outputs the starting column address and signals the SDRAM to begin the burst write operation. Address EM1A[10] is always pulled low to avoid auto precharge. This allows for better bank interleaving performance. |
BT | Burst terminate. The BT command is used to truncate the current read or write burst request. On this device, all the SDRAM accesses are single access except when EMIF controller splits a single access into multiple access (for example, a 32-bit access from CPU is split into two 16-bit accesses if external SDRAM device is 16 bit (NM =1). |
LMR | Load mode register. The LMR command sets the mode register of the attached SDRAM devices and is only issued during the SDRAM initialization sequence described in Section 23.2.5.4. |
REFR | Auto refresh. The REFR command signals the SDRAM to perform an auto refresh according to the internal address. |
SLFR | Self refresh. The self-refresh command places the SDRAM into self-refresh mode, during which the SDRAM provides a clock signal and auto refresh cycles. |
NOP | No operation. The NOP command is issued during all cycles in which one of the above commands is not issued. |
SDRAM Pins: | CKE | nCS | nRAS | nCAS | nWE | BA[1:0] | A[12:11] | A[10] | A[9:0] |
---|---|---|---|---|---|---|---|---|---|
EMIF Pins: | EM1SDCKE | EM1CS[0] | EM1RAS | EM1CAS | EM1WE | EM1BA[1:0] | EM1A[12:11] | EM1A[10] | EM1A[9:0] |
PRE | H | L | L | H | L | Bank/X | X | L/H | X |
ACTV | H | L | L | H | H | Bank | Row | Row | Row |
READ | H | L | H | L | H | Bank | Column | L | Column |
WRT | H | L | H | L | L | Bank | Column | L | Column |
BT | H | L | H | H | L | X | X | X | X |
LMR | H | L | L | L | L | X | Mode | Mode | Mode |
REFR | H | L | L | L | H | X | X | X | X |
SLFR | L | L | L | L | H | X | X | X | X |
NOP | H | L | H | H | H | X | X | X | X |