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[APB] Assert timing of PSTRB and PPROT

Hi All,

I have a question about assert timing of PSTRB and PPROT.

I think APB4 spec (IHI0024C_amba_apb_protocol_spec.pdf) does not describe when PSTRB and PPROT should be asserted.
I guess these signals should be asserted while PSEL is high like PADDR and PWDATA.

Is my understanding correct?

Regards,
Taichi Ishitani

Top replies

Colin Campbell over 5 years ago +1 verified

Yes, exactly what you describe. All "control" signals (other than PENABLE) in an APB transfer should be constant for the entire transfer. Only PREADY, PSLVERR and PRDATA should change after PENABLE goes...
Colin Campbell over 5 years ago in reply to Taichi Ishitani +1 verified

I thought that was the point of your initial question, the spec does not show this, so my reply attempted to explain what IS required. Regarding my earlier comment about control signals staying constant...
Colin Campbell over 5 years ago in reply to Taichi Ishitani +1 verified

To be honest I'm not sure the spec needs updating to explicitly cover these signals. PPROT is a control signal just like PADDR or PWRITE, so it seems reasonable to assume it would have exactly the same...

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0 Taichi Ishitani over 5 years ago in reply to Colin Campbell

Thank you again for your kindly replies.
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0 Taichi Ishitani over 5 years ago in reply to Colin Campbell

Thank you again for your kindly replies.
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