Difference Between AHB and AXI

AHB vs AXI

AHB is Advanced High-performance Bus and AXI is Advanced eXtensible Interface. Both the ABH and AXI are Bus masters, which are really different in many aspects.

When the Advanced High-performance Bus is a single channel Bus, the Advanced eXtensible Interface is a multi- channel Bus. The AHB is also a shared Bus whereas the AXI is a read/write optimized bus.

In AHB, each of the bus masters will connect to a single-channel shared bus. On the other hand, the bus master in AXI will connect to a Read data channel, Read address channel, Write data channel, Write address channel and Write response channel.

Another difference that is noticed is that the Bus latencies in AHB start lower than the AXI. The AHB starts at 16 Byte transactions where as the AXI starts at 64 Byte transactions. It can also be seen that the AHB Bus utilization is higher than AXI utilization. Moreover, The Advanced eXtensible Interface uses around 50 per cent more power, which means that AHB has an edge over it.
Advanced eXtensible Interface is the third generation of Advanced Microprocessor Bus Architecture interface. Some of the features of AXI incude separate address/control and data phases, burst based transactions with start address issued, support for unaligned data transfers using byte strobes, easy addition of register stages to provide timing closure and issuing of multiple outstanding addresses. The AXI, which suits high speed sub-micrometer interconnect, mainly targets high clock frequency system designs and high performance.
Some of the features of Advanced High-performance Bus includes single edge clock protocol, several bus masters, split transactions, pipelined operations, burst transfers, non-tristate implementation and large bus-widths.

Summary
1. AHB is Advanced High-performance Bus and AXI is Advanced eXtensible Interface.
2. When the Advanced High-performance Bus is a single channel Bus, the Advanced eXtensible Interface is a multi- channel Bus.
3. In AHB, each of the bus masters will connect to a single-channel shared bus. On the other hand, the bus master in AXI will connect to a Read data channel, Read address channel, Write data channel, Write address channel and Write response channel.
4. The AHB is also a shared Bus whereas the AXI is a read/write optimized bus.
5. Bus latencies in AHB starts lower than the AXI.
6. The Advanced eXtensible Interface uses around 50 per cent more power, which means that AHB has an edge over it.
7. AHB Bus utilization is higher than AXI utilization

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