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MPC5674F  External Multiplex Bus CS need Variable Wait State Access

Question asked by Steven Petrofsky on Jul 2, 2019
Latest reply on Jul 8, 2019 by David Tosenovjan

Most processors have an RDY signal line to tell the bus to hold until I am done.

 

Configuration:  A  MPC5674F processor EBI external Multiplexed mode using chip select Access.  

 

Problem:          If a peripheral tied to a single /CS on that external bus needs requires an extra  2-3 wait states only part of the time, and "0" wait for states the majority of the time.

 

QUESTION:      How do I tell the bus to extend add waits when the D_TA (bus acknowledge) signal is automatically internally generated.   

  1. Can I override the D_TA to extend that bus access?
  2. Pull another line to inform the processor that the bus transfer is not complete and need more time?

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