Interface Protocols · All levels

Interface Protocols Cheatsheet

Dense reference for protocol debug, integration, and interview answers.

Debug order

diagram

SIGNAL -> LAYER -> CONTRACT -> METRIC -> DEBUG

AMBA: AR/AW/W/R/B, IDs, bursts, response, ordering
ACE/CHI: snoop, home node, shareability, line state, retry
DDR: controller/PHY, training, refresh, bank conflicts, ECC
PCIe/CXL: TLP, DLLP, LTSSM, credits, enumeration, attach mode
Peripheral: reset state, register map, interrupt, DMA, driver contract
Verification: VIP monitor, scoreboard, assertion, coverage, compliance

Questions before proposing a fix

Which transaction failed first?
Which layer owns forward progress?
Is the observed behavior illegal or merely unexpected?
Which metric proves product impact?
Which artifact proves root cause?
Which regression protects compatibility?

Practice this lesson