Browse Prior Art Database

Personal Computer System to Intel 80452-Based Adapter Download Algorithm

IP.com Disclosure Number: IPCOM000099867D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 8 page(s) / 184K

Publishing Venue

IBM

Related People

Landry, JA: AUTHOR [+3]

Abstract

This article describes the use of a direct memory access (DMA) and a first-in, first-out (FIFO) buffer to download firmware to an 80452-based adapter.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Personal Computer System to Intel 80452-Based Adapter Download Algorithm

       This article describes the use of a direct memory access
(DMA) and a first-in, first-out (FIFO) buffer to download firmware to
an 80452-based adapter.

      During the life of an automotive interface adapter card, many
small functional changes occur.  Most of the changes are handled in
firmware.  To meet the need for flexible downloadable firmware, a
download algorithm is required for an 80452 microcontroller-based
adapter card. The 80452 microcontroller consists of a host command
register as well as a 128-byte FIFO buffer.  An external RAM and ROM
are used on the adapter card for the firmware, as shown in Fig. 1,
which is a block diagram of the 80452-based microcontroller adapter
card.  A simple, but crude method for downloading the code is through
the use of the host command register.  Because of the handshaking
required from the 80452 and the length of the instructions used to
transfer a byte of code to RAM, a faster algorithm is needed.  The
host would waste too much time waiting for the 80452 to transfer a
byte.

      Two unique features of the 80452 were used in creating the
algorithm, the 128-byte FIFO buffer and a DMA channel. The FIFO
buffer is initialized to accept 127 bytes from the host when the FIFO
buffer empty flag toggles from low to high.  The host can download
bytes until the flag toggles from high to low.  The DMA channel is
initialized to transfer data from the FIFO buffer to external memory
as soon as one byte is put into the FIFO buffer by the host.

      The algorithm for the download also includes a checksum routine
and a code-placement verification routine.  To optimize the amount of
time the host is required for handshaking, all code verification
occurs after all the code is downloaded.

      Figs. 3A through 3F comprise a flow chart of the algorithm of
this disclosure.  The algorithm begins by waiting for a "download
begin" command from the host.  Two commands are accepted: a download
command or a download debug command.  A download debug command is
provided to determine the cause of a failure in the download.  When
executed, an error code is sent to the host for t...