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AN-724
APPLICATION NOTE
One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Te l: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
ADuC70xx Serial Download Protocol
Rev. C | Page 1 of 8
INTRODUCTION
A key feature of the MicroConverter® product family is the ability
of the devices to download code to their on-chip Flash/EE pro-
gram memory while in-circuit. An in-circuit code download is
conducted over the device UART serial port, and is thus commonly
referred to as a serial download. The serial download capability
allows developers to reprogram the part while it is soldered
directly onto the target system, avoiding the need for an external
device programmer. The serial download feature also enables
system upgrades to be performed in the field; all that is required
is serial port access to the MicroConverter. This means manu-
facturers can upgrade system firmware in the field without
having to swap out the device.
Any MicroConverter device can be configured for serial down-
load mode via a specific pin configuration at power-on or during
the application of the external reset signal. For the ADuC70xx
family of MicroConverters, the
BM
input pin is pulled low
through a resistor (1 k). If this condition is detected by the
part at power-on or during application of a hard reset input,
the part enters serial download mode. In this mode, an on-chip
resident loader routine is initiated. The on-chip loader configures
the device UART and, via a specific serial download protocol,
communicates with any host machine to manage the download
of data into its Flash/EE memory spaces. The format of the
program data to download must be little endian.
Note that serial download mode operates within the standard
supply rating of the part (2.7 V to 3.6 V). Therefore, there is no
requirement for a specific high programming voltage because it
is generated on-chip. Figure 1 shows how to enter serial down-
load mode on an evaluation board.
As a QuickStart™ development tool, a Windows® program
(ARMWSD.exe) is provided by Analog Devices, Inc. This
program allows the user to download code from PC serial ports
COM1 to COM31, inclusive, to the MicroConverter. Note,
however, that any master host machine (PC, micro-controller,
or DSP) can download to the MicroConverter once the host
machine adheres to the serial download protocols detailed in
this application note.
This application note details the MicroConverter serial
download protocol, allowing end users to understand and
to successfully implement this protocol (embedded host to
embedded MicroConverter) in an end-target system.
For the purposes of clarity, the term host refers to the host machine
(PC, microcontroller, or DSP) attempting to download data to
the MicroConverter. The term loader refers to the on-chip serial
download firmware on the MicroConverter.
(A) RELEASED
(RESET = 1) (RESET = 1)(SERIAL DOWNLOAD = 1)
(RESET = 1) (SERIAL DOWNLOAD = 1)
(SERIAL DOWNLOAD = 0)
(RESET = 1)
(D) RELEASE (E) RELEASE
(SERIAL DOWNLOAD = 0)
(RESET = 0) (SERIAL DOWNLOAD = 0)
(B) PUSH (C) PUSH
04844-001
Figure 1. MicroConverter in Serial Download Mode
