i am not able to understand working of this CACHE signal pleas explain with simple example.
thank you!
I'm not really sure what you want to know.
The AxCACHE signals in the specification taken together indicate "memory types"(see section A4.4), and each memory type then has particular requirements on the system on how they are performed. So your master would use a memory type encoding that will require the system to implement that transfer as the master requires. And a slave would use the memory type indicated to work out how it can respond to this and other transfers.
Alternatively you can use the AxCACHE bits in isolation to determine if a transfer can be cached or buffered.
As far as the "working of the CACHE signal" is concerned, it is a write or read address channel signal, so the information on it is transferred using the AxVALID and AxREADY handshake signals.
If the above does not answer your questions, can you explain in more detail what it is you do not understand, and hopefully someone might then be able to come up with a simple example to help your understanding ?
Thanks for replay
My question is why we need to write in cache memory instead of final destination?
Final destination memory is often off-chip, so subject to significant latency. Keeping a local copy on-chip of frequently accessed external data reduces latency. This local on-chip memory used to store frequently accessed data is what is referred to as a cache.
So getting back to the AXI protocol, it signals different memory types using the AxCACHE signals, so that system components such as caches know what to do with those transfers. Some memory types are not cacheable, those being the "Device" types. These would be used for accesses to external peripherals, where you want this access to read the latest external value, or immediately update the external device, so you don't want those accesses instead going to a local "cache".
There are various descriptions of caches and how they operate available on the internet, so I'm sure they would give you much better descriptions of how to use them in your design that anything I can describe, so I won't try to go into further details here.