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[APB] Assert timing of PSTRB and PPROT

Taichi Ishitani

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

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  • +1 Arm Employee Badge in reply to Taichi Ishitani

    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 timing requirements. Similarly PSTRB is very closely related to PWDATA, so should have the same timing requirements.

    However if any update to the APB protocol is proposed, I'm sure these description updates will be included just to avoid any doubt.

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  • +1 Arm Employee Badge in reply to Taichi Ishitani

    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 timing requirements. Similarly PSTRB is very closely related to PWDATA, so should have the same timing requirements.

    However if any update to the APB protocol is proposed, I'm sure these description updates will be included just to avoid any doubt.

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