Operation - Motorola DragonBall MC9328MX1 Reference Manual

Chapter 9
Bootstrap Mode Operation
Bootstrap mode is designed to allow you to initialize a target system and download programs or data to the
target system's RAM using the UART 1 or UART 2 controller. After a program is downloaded, it can be
executed, which gives you a simple debugging environment for failure analysis and a channel to update
programs stored in flash memory. Bootstrap mode has the following capabilities:
• Allows you to initialize your system and download programs and data to system memory using
UART 1 or UART 2
• Accepts execution commands to run programs stored in system memory
• Supports memory and register read and write operations of selectable data size (byte, half-word, or
word)
• Provides an 8-word instruction buffer for ARM920T vector table storage, instruction storage and
execution

9.1 Operation

In bootstrap mode, the MC9328MX1's UART 1 and UART 2 controllers are initialized to auto-baud
detection mode, no parity, 8-bit character length, and 1 stop bit, and then they are ready to accept bootstrap
data download. The first character received must be
used and which UART port is being used for bootstrapping. The first character is not part of a program or
data being downloaded. To download the data or program, the code must be converted to a bootstrap
format file, which is a text file that contains bootstrap records. A DOS-executable program,
can be downloaded from the DragonBall Web site to convert an S-record file to a bootstrap format file.
The MC9328MX1's internal registers must be initialized as the target system before a program can be
downloaded to system memory. Because these internal registers can be treated as a type of memory, each
of them can be initialized by issuing a bootstrap record.
The bootstrap design provides an 8-word instruction buffer to which ARM920T core instructions can be
downloaded. The buffers are word-access only. This feature enables the ARM920T core instructions to be
run even if the memory systems are disabled or in a core stand-alone system. The instruction buffer starts
at 0x00000004. Regardless of the operation (initializing internal registers, downloading a program to
system RAM, or issuing a core instruction), bootstrap mode will only accept bootstrap record transfers that
are made with the UART. The record type determines what action will occur.
The instruction buffer allows the user to download the vector table to the buffer without the use of external
ROM or Flash. The feature provides the user a fast and easy environment to use IRQ during program
debugging.
MOTOROLA
or . This character determines the baud rate to be
a A
Bootstrap Mode Operation
,
STOB.EXE
9-1