Doubt in AMBA-AHB

[sri]

Hi.

I am quite new to AMBA and had a doubt.

The protocol says that when Master puts IDLE on the bus, Slave should
respond with a Zero-wait state OKAY response. On that i had a doubt.
Consider at CLK1 master puts address phase for the last transfer of a
burst.
Then at CLK2 Master puts IDLE on HTRANS and the Data phase of the prev
Address..
Also slave puts a wait state as it cannot respond to the Data phase..
So at CLK3 shud the slave put a OKAY response for the IDLE of CLK2 or
just respond for the pending Data phase, if it can..

Hope someone can help on this one.. Thanks in advance..

Regards,
Srinath Buyao.

 

[Joseph]

sri wrote:

Hi.

I am quite new to AMBA and had a doubt.

The protocol says that when Master puts IDLE on the bus, Slave should
respond with a Zero-wait state OKAY response. On that i had a doubt.
Consider at CLK1 master puts address phase for the last transfer of a
burst.
Then at CLK2 Master puts IDLE on HTRANS and the Data phase of the prev
Address..
Also slave puts a wait state as it cannot respond to the Data phase..
So at CLK3 shud the slave put a OKAY response for the IDLE of CLK2 or
just respond for the pending Data phase, if it can..

Hope someone can help on this one.. Thanks in advance..

Regards,
Srinath Buyao.

Clock cycle number 3 will be a response for the data phase.

When a slave output HREADY as 0, the idle transfer (or any other
transfer on the address phase) is not committed. So the data phase can
continue until the device response with a HREADY set to 1.

And if HREADY = 1 and HTRANS = IDLE, the idle transfer is commited, then
on next cycle, all slaves on the AHB buse must response with OKAY with
HREADY=1 (zero wait state).

Joseph