Datasheet 搜索 > 微控制器 > Maxim Integrated（美信） > DS89C450-MNG 数据手册 > DS89C450-MNG 用户编程技术手册 4/7 页
器件3D模型￥ 82.045
DS89C450-MNG 用户编程技术手册 - Maxim Integrated（美信）
制造商:
Maxim Integrated（美信）
分类:
微控制器
封装:
DIP-40
Pictures:
3D模型
符号图
焊盘图
引脚图
产品图
页面导航:
应用领域在P5
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DS89C450-MNG数据手册
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Figure 3. Physical connection, DS5000-based designs.
The bootloader uses the clock source attached to the XTAL1/XTAL2 pins as its time base. If a crystal is
used, it must meet the recommendations (resonance in fundamental mode, parallel AT-cut, amount of
load capacitance, etc.) listed in the datasheet for that device. Because the bootloader relies on internal
timers for the autobaud measurements, it has a few restrictions on the range of frequencies compatible
with the bootloader. Please consult the User's Guide for your particular device for the range of clock
frequencies that are compatible with the bootloader.
Software
After the bootstrap loader has been activated, the microcontroller will poll the serial port, looking for a
carriage return (0Dh) character in the eight data bit, no parity, one stop bit (8-N-1) format. The bootstrap
loader software measures the length of the high and low spaces within that character to determine the
baud rate of the host system. This autobaud feature allows the bootstrap loader to communicate with a
number of host systems without being limited to a fixed baud rate.
Once the bootstrap loader has been invoked and the baud rate calculated, the device will transmit a
sign-on banner identifying the device. Then the device will display a prompt character and wait for
commands. Again, the command set varies between device families, but they are usually single ASCII
characters and will always include versions of load, verify, and erase memory commands. Consult the
specific device user guide for a command listing.
The simple bootstrap loader interface permits several ways to communicate between the PC and target
microcontroller. The simplest is to use the Microcontroller Tool Kit (MTK2) from Maxim. MTK2 is a PC
utility for communicating with the ROM/bootstrap loader of most Maxim microcontrollers. It is a
highfeatured front-end, simplifying the task of configuring the target and uploading and downloading
code and configuring special functions.
A main window allows the user to type commands directly to the target microcontroller. Many commands
supported by the target loader can be entered directly from the main window of MTK2. Special support is
provided for filerelated commands that require special communication protocols.
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