SPRUII0F May 2019 – June 2024 TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S
Different sources within the MCU can make requests to the EMIF. These requests consist of accesses to the SDRAM memory, the asynchronous memory, and the EMIF registers. The EMIF can process only one request at a time. Therefore, a high performance master arbitration block exists within the MCU to provide prioritized requests from the different sources to the EMIF. The sources are:
If a request is submitted from two or more sources simultaneously, the crossbar switch forwards the highest priority request to the EMIF first. Upon completion of a request, the master arbitration block again evaluates the pending requests and forwards the highest priority pending request to the EMIF.
The master arbitration block always allows RD access from any of the masters. But for WR access (or execute access), the master arbitration block only allows access of masters from a CPU subsystem that takes master ownership of the EMIF module based on the configuration in the EMIF1MSEL register in the Memory Controller module. Note that only the EMIF1 has access from both the CPU subsystems; hence, the concept of grab-semaphore is applicable for the EMIF1 only.
When the EMIF receives a request, it is possible that the request is not immediately processed. In some cases, the EMIF performs one or more auto-refresh cycles before processing the request. For details on the EMIF internal arbitration between performing requests and performing auto-refresh cycles, see Section 12.2.13.