AN2153 Freescale Semiconductor / Motorola, AN2153 Datasheet - Page 23

• Manufacturer Part Number: AN2153
• Description: A Serial Bootloader for Reprogramming the MC9S12DP256 FLASH Memory
• Manufacturer: Freescale Semiconductor / Motorola

Set Baud Rate
Command
Bootloader Software
AN2153
MOTOROLA
While the default communications rate of the bootloader is 9600 baud,
this speed is much too slow if the majority of the MC9S12DP256’s
FLASH is to be programmed; however, it provides the best compatibility
for initial communications with most terminal programs. The set baud
rate command allows the bootloader communication rate to be set to
one of four standard baud rates. Using a baud rate of 57,600 allows the
entire 256 K of FLASH to be programmed in just under two minutes.
Typing a lowercase c on the terminal causes the prompt shown in
Figure 13
number 1 through 4 on the keyboard will select the associated baud rate
and issue a secondary prompt indicating that the terminal baud rate
should be changed. After changing the terminal baud rate, pressing the
enter or return key will return to the main bootloader prompt. The
selected baud rate will remain set until the target system is reset.
The software implementing the serial FLASH bootloader, shown in
Listing, consists of seven basic parts: startup code, bootloader control
loop, programming and erase code, serial communications routines, an
S-record loader and a secondary interrupt vector jump table. The code
is written in a position independent manner so that the generated object
code will execute properly from any address.
Freescale Semiconductor, Inc.
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1) 9600
2) 38400
3) 57600
4) 115200
? 3
Change Terminal BR, Press Return
to be displayed on the host terminal’s screen. Entering a
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Figure 13. Change Baud Rate Prompt
Bootloader Software
Application Note
Code
23