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AHB Slave HREADY

Hello

I am new to AMBA and I am writing code AHB slave in one of my project, I have read specs.

My question is Is there any specific condition for slave when it gives HREADY low?

I am confused with HREADY signal that it is provided by the slave but at which time and in which condition HREADY becomes low?

Thanks in advance.

  • Hi ajoo,

    HREADY is used by a slave to add wait states to the data phase of an access, so whenever it needs more time to complete a transfer request. The reasons why that slave might need to add a wait state depend on the slave design.

    For example if the slave is a bridge to an APB slave, the APB access takes a minimum of 2 cycles to complete, so at the end of 2 cycles the AHB slave "bridge" can then drive HREADY high to signal the APB access has completed, but it needed to hold HREADY low for the 2 cycles during which the APB access was occuring (it needed to stall the master).

    Hope that helps,

    JD