Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Method of Dynamically Tuning Burst-Mode Loading on a Shared Memory Real Time Device

IP.com Disclosure Number: IPCOM000110942D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Lisle, RJ: AUTHOR [+3]

Abstract

Some bus attached I/O devices perform their communication with the host processor via a shared memory. Depending on the particular implementation, accesses to this memory by the host can result in the I/O device suspending its operation. For example, on the IBM M-Audio Capture and Playback Adapter (M-ACPA), the host can read or write to the TMS320C25 DSP's program and data memory. Each access by the host can result in the DSP suspending its operation for several instruction cycles. If the DSP is performing real time operations, such as updating an Audio D/A converter to generate sound, then there may be a maximum number of host accesses that can occur during a given period at which point additional accesses result in the DSP falling behind in its work. This can become apparent to the user as audible clicks or pops.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

Method of Dynamically Tuning Burst-Mode Loading on a Shared Memory
Real Time Device

      Some bus attached I/O devices perform their communication with
the host processor via a shared memory.  Depending on the particular
implementation, accesses to this memory by the host can result in the
I/O device suspending its operation.  For example, on the IBM M-Audio
Capture and Playback Adapter (M-ACPA), the host can read or write to
the TMS320C25 DSP's program and data memory.  Each access by the host
can result in the DSP suspending its operation for several
instruction cycles.  If the DSP is performing real time operations,
such as updating an Audio D/A converter to generate sound, then there
may be a maximum number of host accesses that can occur during a
given period at which point additional accesses result in the DSP
falling behind in its work.  This can become apparent to the user as
audible clicks or pops.  A solution to this problem, and the subject
of this disclosure, is to provide a mechanism by which the host can
determine the point at which it will cause the DSP to fall behind.
This is done as follows:

1.  The DSP performs its work in discrete time intervals.  Typically
    this interval is the amount of data stored in a D/A buffer, 256
    samples, for example.

2.  After completing its work for any given period, the DSP enters
    into an idle loop, waiting for the beginning of the next period.
    This could be signalled by an interrupt fro...