Search

Technical Discussion Group Forum

This forum is provided for user discussion. While Beacon EmbeddedWorks support staff and engineers participate, Beacon EmbeddedWorks does not guarantee the accuracy of all information within in the Technical Discussion Group (TDG).

The "Articles" forums provide brief Articles written by Beacon EmbeddedWorks engineers that address the most frequently asked technical questions.

To receive email notifications when updates are posted for a Beacon EmbeddedWorks product download, please subscribe to the TDG Forum of interest.

TDG Forum

PrevPrev Go to previous topic
NextNext Go to next topic
Last Post 02 May 2005 07:41 PM by  yuanfei@addvalue.com.sg
how to use nPCWAIT signal?
 2 Replies
Sort:
You are not authorized to post a reply.
Author Messages
yuanfei@addvalue.com.sg
New Member
New Member
Posts:


--
27 Apr 2005 01:29 AM
    I am wondering what is the purpose nPCWAIT signal. I did not see any hardware signal generation depends on this signal. according to Application notes "Interfacing Static memory controller with IO devices" . Seems the wait state generation is also not depends on it, instead just counting clock. So how this pin is used exactly. Does any where get soem concrete documents or timing diagram for this?

    Thanks
    kurtl@logicpd.com
    New Member
    New Member
    Posts:


    --
    29 Apr 2005 10:51 AM
    nPCWAIT is the bus cycle extension signal for PCMCIA card access timing.

    Section 5.1.7.2 PC Card Timing of the LH7A404 User's Guide covers this in detail, but here is a quick summary. If a PC card requires wait states beyond the maximum programable wait state value, the WEN bit can be set which allows the external device to assert nPCWAIT. While nPCWAIT is low the current bus transaction will be held beyond the programmed wait states until the external device deasserts the signal ending the current transaction.

    I tried to dig up a timing diagram from the Sharp Data Sheet, but at this time they do not publish that signal on their PCMCIA timing waveforms.
    yuanfei@addvalue.com.sg
    New Member
    New Member
    Posts:


    --
    02 May 2005 07:41 PM
    Thanks
    You are not authorized to post a reply.