Advantages of AMBA AHB | Disadvantages of AMBA AHB
This page covers advantages and disadvantages of AMBA AHB bus. It mentions benefits or advantages of AMBA AHB and drawbacks or disadvantages of AMBA AHB.
Introduction: AMBA stands for Advanced Micro-controller bus architecture. It is the bus architecture designed for microcontrollers. It is the open standard which defines on chip interconnect specification for the connection and management of functional blocks in SoC (System on Chip). It enables usage of large number of peripherals and their connections with more than one microcontrollers or microprocessors.
AMBA standards cover various bus specifications in different versions.
• Advanced High Performance Bus (AHB)
• Advanced System Bus (ASB)
• Advanced Peripheral Bus (APB)
• Advanced Trace Bus (ATB)
• AMBA Extensible Interface (AXI)
What is AMBA AHB?
AMBA AHB is designed for high performance and high clock frequency system modules. AHB supports efficient connection of processors, on-chip memories and off chip external memory interfaces.
The AMBA AHB offers high performance, pipelined operation, multiple bus masters, burst transfers, split transactions, single clock edge operation, single cycle bus master handover, non-tristate implementation and wide data bus configurations (64/128 bits).
The figure-1 depicts AMBA based SoC design which uses AHB or ASB protocols for high bandwidth interconnect and APB protocol for low bandwidth peripheral interconnects. AHB to APB bridge or ASB to APB bridge is used to connect high bandwidth and low bandwidth peripherals together.
The typical AMBA AHB system consists of AHB master, AHB slave, AHB arbiter and AHB decoder.
AHB master : It initiates read and write operations by using address and control information. Only one bus master is allowed to use bus at one time.
AHB slave : It responds to read or write operation as per address space range.
AHB arbiter : It ensures only one bus master is allowed to initiate data transfers at one time. The protocol is fixed but it allows implementation of arbitration algorithm as per application requirements.
AHB decoder : It is used to decode address of each transfer and provides select signal for the slave. A single centralized decoder is needed in all the implementations. Refer AMBA AHB protocol specifications for more information.
Benefits or advantages of AMBA AHB
Following are the benefits or advantages of AMBA AHB:
➨It offers high performance, pipelined operation and high bandwidth operation.
➨It supports multiple bus masters, burst transfers and split transactions.
➨AHB can be implemented as single shared bus, hierarchical bus and as bus matrix.
➨Bus arbitration solves many ordering problems.
➨It is easy to add new blocks.
➨It offers excellent latency and low power consumption.
➨It delivers cheaper boards.
Drawbacks or disadvantages of AMBA AHB
Following are the drawbacks or disadvantages of AMBA AHB:
➨It has bandwidth bottleneck.
➨It does not scale well when blocks are added.
➨Multiple outstanding transactions are not handled well.