[2023 School Recruitment Questions] Summary of Common Interview Questions (7. Common Bus Protocols) (Continuously updated with subsequent interviews....)

1. The difference between AHB/APB/AXI protocol in AMBA bus

AHB (Advanced High-performance Bus) advanced high-performance bus.
APB(Advanced Peripheral Bus) Advanced Peripheral Bus
AXI (Advanced eXtensible Interface) Advanced Extensible Interface

• AHB is a bus designed for high-efficiency, high-bandwidth and high-speed system modules. It can connect high-efficiency modules such as microprocessors, on-chip or off-chip memory modules, and DMA.
• APB is mainly used in low speed and low power peripheral devices, which can optimize power consumption and complex interfaces for peripheral devices.APB provides a communication bridge between AHB and low-bandwidth peripheral devices, so APB is a secondary expansion bus of AHB.
• AXI high speed, high bandwidth, pipelined interconnection, one-way channel, only need the first address, parallel read and write, support out-of-order, support unaligned operations, effectively support high initial delayPeripherals, there are a lot of connections.

AHB Agreement

1. Composition of AHB

• Master: Can initiate read and write operations, provide address and control signals, and only one Master will be activated at the same time.
• Slave: Responds to read and write operations in the given address range and returns success, failure or wait status to the Master.
• Arbiter: Responsible for ensuring that only one Master is working on the bus at a time.The arbitration protocol is specified, but the arbitration algorithm can be determined according to the application.