SPRUJB6B November 2024 – May 2025 AM2612
PSRAMs unlike Flash, requires DQS(Data Strobe) signals to be driven from device during the write phase also. The OSPI controller inherently does not support driving DQS signal during write phase. To support this requirement, DQS signal is generated in the SoC and given to the PSRAM. The logic drives the DQS signal to 0 during the write data phase of the PSRAM.
DQS signal is driven to 0 only during the write data phase, and not during the command, address and dummy cycle phase(Latency Code Phase) of the protocol. Thus the SoC logic requires the information regarding the cycle counts for the command, address and dummy cycle phase(Latency Code Phase).
This information is provided to to the SoC logic using OSPI1_DQS_CONTROL register in MSS_CTRL register space.OSPI1_DQS_CONTROL_EN enables the DQS control logic, while OSPI1_DQS_CONTROL_COUNTER_CMP_VALUE provides the overall count required for waiting before driving DQS during write data phase, to the SoC hardware logic.
Based on the ablove 2 information provided, the hardware logic in SoC drives the DQS line and the PAD controls for the DQS line on SoC.
Figure 13-223