How do you connect an AHB slave to an AHB-lite system?
AHB slaves are fully AHB-lite compatible, so can be connected directly, unless they generate SPLIT or RETRY responses. If the AHB slave generates RETRY responses, you will need an Ahb2Ahb bridge (there are several examples in ARM's AMBA Design Kit (ADK)) between the AHB slave and the AHB-lite system. This Ahb2Ahb bridge will locally service the RETRY response, while holding HREADY low (1'b0) to the AHB-lite system. If the AHB slave generates SPLIT responses then in addition to the Ahb2Ahb bridge required for RETRY responses, you would also need a local Dummy master and an Arbiter. SPLIT responses require the arbiter to grant a different master, so we need the dummy master on this local full-AHB bus to drive IDLE cycles until the slave is able to complete the SPLIT transfer.
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