SPRUHX5I August 2014 – May 2024 TMS320F28374S , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376S , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28378S , TMS320F28379S
An asynchronous read is performed when any of the requesters mentioned in Section 24.2.2 request a read from the attached asynchronous memory. After the request is received, a read operation is initiated once the request becomes the EMIF's highest priority task, according to the priority scheme detailed in Section 24.2.13. In the event that the read request cannot be serviced by a single access cycle to the external device, multiple access cycles are performed by the EMIF until the entire request is fulfilled. The details of an asynchronous read operation in select strobe mode are described in Table 24-23. Also, Figure 24-13 shows an example timing diagram of a basic read operation.
Time Interval | Pin Activity in Select Strobe Mode | |
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Turnaround period | Once the read operation becomes the highest priority task for the EMIF, the EMIF waits for the programmed number of turnaround cycles before proceeding to the setup period of the operation. The number of wait cycles is taken directly from the TA field of the asynchronous n configuration register (ASYNC_CSn_CR). Between each access (Write or Read) EMIF inserts two cycles of delay even though TA field is programmed as 0. After the EMIF has waited for the turn-around cycles to complete, the EMIF again checks to make sure that the read operation is still the highest priority task. If so, the EMIF proceeds to the setup period of the operation. If the read operation is no longer the highest priority task, the EMIF terminates the operation. | |
Start of the setup period | The following actions occur at the start of the setup period:
| |
Strobe period | The following actions occur during the strobe period of a read
operation:
| |
End of the hold period | At the end of the hold period:
|