Ending transactions - data phase, Computer Engineering

Ending transactions:

Either side may request that a burst end after the present data phase. Simple PCI component that do not support multi-word bursts will always request this instantaneously. Even devices that do support bursts will have some restriction on the maximum length they can support, like as the end of their addressable memory.

The initiator can mark any data phase as the last one in a transaction by deserting FRAME# at the same time as it asserts IRDY#. The cycle after the target asserts TRDY#, the last data transfer is complete, both sides dessert their individual RDY# signals, and the bus is make idle again. The master may not dessert FRAME# before asserting IRDY#, nor may it assert FRAME# whereas it waiting, with IRDY# asserted, for the target to assert TRDY#.

The only minor exception is a master abort termination is happen when no target responds with DEVSEL#. Clearly, it is useless to wait for TRDY# in such type of case. However, even in this case, the master has to assert IRDY# for at least 1 cycle after deserting FRAME#. (Usually, a master will assert IRDY# before retain DEVSEL#, so it have to simply hold IRDY# asserted for 1 cycle longer.) It is to ensure that bus turnaround timing rules are obeyed on the FRAME# line.

The target requests the initiator end a burst by asserting STOP#. The initiator will then finish the transaction by deserting FRAME# at the next legal chance. If it desires to transfer any more data, it will continue in a separate transaction. There are various ways to do this:

Disconnect with data

If the target asserts TRDY # and STOP # at the same time, it indicates that the target wishes this to be the last data phase. For instance, a target that does not support burst transfers will always do it to force single-word PCI transactions. It is the most efficient way for a target to stop a burst.

Disconnect without data

If the target asserts STOP# without asserting TRDY#, it indicates that the target desire to stop without transferring data. STOP# is considered corresponding to TRDY# for the purpose of ending a data phase, but data is not transferred.

Retry

A Disconnection without data before transferring any data is a retry and unlike other type PCI transactions, PCI initiators are needed to pause slightly before continuing the operation. Observe the PCI specification for details.

Posted Date: 10/13/2012 7:35:28 AM | Location : United States







Related Discussions:- Ending transactions - data phase, Assignment Help, Ask Question on Ending transactions - data phase, Get Answer, Expert's Help, Ending transactions - data phase Discussions

Write discussion on Ending transactions - data phase
Your posts are moderated
Related Questions
DOM is the Document Object Model (DOM) which is an interface specification handled by the W3C DOM Workgroup that explains an application independent mechanism to access, parse, or

What do you mean by system calls? System calls give the interface among a process and the operating system. When a system call is executed, it is treated as by the hardware as

Write a function that will get a variable number of input arguments: the length and width of a rectangle, and possibly also the height of a box that has this rectangle as its base.


Define speculative execution. Speculative execution means that instructions are implemented before the processor is particular that they are in the correct execution sequence.

Define the three prime processes of uml The three prime processes were OMT (Rumbaugh), OOSE (Jacobson) and Booch. OMT was strong in analysis, while Booch was strong in design a

Advntages of parallel processing oversequential computation Parallel computing has the following benefits over sequential computing: i)    Accumulate time ii)   Solves b

Vector reduction Instructions When operations on vector are being decreased to scalar items as a result then these are vector reduction instructions. These instructions are ref

TARGET = "_self" "_self" puts the new document in the same window and frame as current document. "_self" works the same as if you hadn't used TARGET at all.

What are the different layers of TCP/IP protocol stack? Layers in the TCP/IP protocol architecture are:- o  Application Layer o   Host-to-Host Transport Layer,  o  Net