SPRUJ79 November 2024 F29H850TU , F29H859TU-Q1
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 controller 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 controller arbitration block again evaluates the pending requests and forwards the highest priority pending request to the EMIF.
The controller arbitration block always allows RD access from any of the controller. But for WR access (or execute access), the controller arbitration block arbitrates between the accesses controller from multiple resources (CPU1/2/3 and RTDMA) controller using a round robin priority scheme.
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 14.2.13.