AT91RM9200DK U-Boot User Manual
Version: V1.0
CONFIDENTIAL – INTERNAL USE ONLY
Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s
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port devices or systems.
Reference: ABP-STD-BOOT-003
ARM-Based Product Application Group
Release Date: 10-Jul-2003
Revision History
Date 10-Jul-2003 Name AT91RM9200DK U-Boot User Manual
Version V1.0 Reference ABP-STD-BOOT-003
ARM-Based Product Application Group
ATMEL CONFIDENTIAL – INTERNAL USE ONLY
Revision Date Author Comments
V1.0 24-Jun-2003 NLe Creation.
Page i
Table of Contents
Date 10-Jul-2003 Name AT91RM9200DK U-Boot User Manual
Version V1.0 Reference ABP-STD-BOOT-003
ARM-Based Product Application Group
ATMEL CONFIDENTIAL – INTERNAL USE ONLY
1 - Scope................................................................................................................................... 1
2 - Features............................................................................................................................... 1
3 - Overview.............................................................................................................................. 1
3.1 - Description.............................................................................................................................................. 1
3.2 - AT91RM9200 Development Kit Setup.................................................................................................... 2
3.3 - Autoboot Mode and Interactive Mode..................................................................................................... 2
3.4 - Environment Variables ........................................................................................................................... 2
4 - Data Download.................................................................................................................... 4
4.1 - Download via the serial port ................................................................................................................... 4
4.2 - Download via the Ethernet Interface ...................................................................................................... 4
5 - Memory Operations............................................................................................................ 6
5.1 - Generic Memory Operations .................................................................................................................. 6
5.2 - Flash-specific Operations....................................................................................................................... 6
5.3 - DataFlash Features ................................................................................................................................ 7
5.4 - Advanced Features ................................................................................................................................ 8
5.4.1Scripting ............................................................................................................................................ 8
5.4.2Code Execution................................................................................................................................. 9
Go command ............................................................................................. 9
Bootm command........................................................................................ 9
5.5 - Automatic Host Configuration................................................................................................................. 9
6 - U-Boot Reference............................................................................................................. 10
6.1 - Reserved Environment Variables ......................................................................................................... 10
6.2 - Commands ........................................................................................................................................... 11
Page 1 / 15
Date 10-Jul-2003 Name AT91RM9200DK U-Boot User Manual
Version V1.0 Reference ABP-STD-BOOT-003
ATMEL CONFIDENTIAL – INTERNAL USE ONLY
ARM-Based Product Application Group
1 - Scope
This document aims at describing the bootloader embedded in the AT91RM9200DK
development kit. It gives a general overview of U-Boot and a detailed description of the
different commands to use.
It is mainly destined to those who want to know how using U-Boot.
2 - Features
The main features of the U-Boot software for the AT91RM9200 series ARM Based
Products are:
• Standalone primary bootstrap
• Small footprint
• OS-independent
• Auto-boot and interactive modes
• Command line interface
• Non-volatile environment variables
• Flash programming capability
• DataFlash programming capability (only available in latest Open Source download)
• Download through serial interface (Kermit protocol)
• Download through Ethernet (tftp)
• Integrated bootp
• Scripting capability
3 - Overview
3.1 - Description
The U-Boot program is a standalone software application that initializes the
AT91RM9200 processor and then jumps to the main application. If the user sends a
character to the system console during the bootstrap, U-Boot enters interactive mode.
The user is prompted to enter commands on the command line. The commands allow
the processor to read/modify memory areas, set environment variables, download data
from the serial port or from the Ethernet interface and execute code routines.
The U-Boot program is completely standalone. In particular, it is independent of the
operating system and not linked to the main application software. However, it is able to
launch the latter by executing an absolute branch operation.
U-Boot is a project supported by the Open Source community. It is distributed under the
GPL license. See the source code for credits and other licensing information.
Page 2 / 15
Date 10-Jul-2003 Name AT91RM9200DK U-Boot User Manual
Version V1.0 Reference ABP-STD-BOOT-003
ATMEL CONFIDENTIAL – INTERNAL USE ONLY
ARM-Based Product Application Group
3.2 - AT91RM9200 Development Kit Setup
To start the U-Boot software:
• Connect a PC running a terminal emulator such as Kermit or HyperTerminal to the
Serial Debug port of the AT91RM9200DK development board. The default port
parameters are 115200 bps (can be changed later), 8 bits, one stop, no parity, no
flow control. The PC acts as the system console.
• Power-up the board.
The U-Boot starts and supplies a prompt on the terminal emulator.
It is recommended that a network connection is in place when U-Boot is used. In this
case, the network should be connected to the Ethernet interface of the AT91RM9200DK
development board.
3.3 - Autoboot Mode and Interactive Mode
When the AT91RM9200-based system is powered up, a banner is displayed on the sys-
tem console. The user is then prompted to send a character to the system console to
enter the interactive mode. If, after a delay controlled by the bootdelay environment vari-
able, no character is received, U-Boot continues in autoboot mode by attempting to
execute the command defined by the bootcmd environment variable. Typically, this vari-
able contains a “go” command that performs a jump and gives control to the main
application software.
Note that if the bootdelay variable is not defined or does not contain a relevant value, U-
Boot does not attempt the autoboot and will remain in interactive mode. The same fall-
back in interactive mode occurs if the bootcmd variable is undefined.
3.4 - Environment Variables
U-Boot has the ability to define and maintain environment variables in non-volatile mem-
ory. An environment variable may contain any character string. Some variables have a
reserved name which directly impacts the behavior of the system. An example of such a
reserved variable is ipaddr. This variable contains the IP address of the local host in the
quad-dotted notation. For complete information on the reserved environment variables,
refer to Section 6.1.
Other variables are user-defined. Their name can be almost any alphanumeric string
and they may contain any character string for the user's convenience.
The list of currently defined environment variables can be displayed on the console with
the printenv command. The example below shows a typical display following the print-
env command:
Uboot> printenv
baudrate=115200
ipaddr=192.168.1.1
ethaddr=12:34:56:78:9A:BC
serverip=192.168.1.5
Environment size: 80/8188 bytes
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