Datasheet 搜索 > 微控制器 > NXP（恩智浦） > MCHC908JW32FC 数据手册 > MCHC908JW32FC 用户编程技术手册 5/28 页
器件3D模型￥ 61.678
MCHC908JW32FC 用户编程技术手册 - NXP（恩智浦）
制造商:
NXP（恩智浦）
分类:
微控制器
封装:
QFN-48
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技术参数、封装参数在P14
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MCHC908JW32FC数据手册
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AN2398/D
THE ICP PROCEDURE
In-Circuit Programming of FLASH Memory via the USB for the MC68HC908JB8 5
THE ICP PROCEDURE
Using the ICP scheme, assuming the HID is a keyboard, the following would be
the procedure for reprogramming the JB8 user code:
1. With the keyboard plugged to a PC, the user initiates an ICP event by
launching a program on the PC. This program clears the ICP_FLAG
word to zero in the JB8.
2. User unplugs and replugs the USB connector.
3. After replugging, the JB8 detects that ICP_FLAG word is not a
checksum and continues to run the ICP code. The PC detects the
keyboard is in ICP mode, ready for firmware upgrade.
4. User launches a firmware upgrade program on the PC. (A separate
keyboard must be used for this, since the keyboard in question is in ICP
mode.)
5. To prevent unauthorized access, the PC program asks for the 8-byte
security passcode.
6. Once pass security, the user is allowed to erase and program the user
code in the JB8.
7. After user code upgrade, the final step is to program the ICP_FLAG
word checksum.
8. User unplugs and replugs the USB connector.
9. After replugging, the JB8 detects that ICP_FLAG word is a checksum,
and continues to run the user code — the normal operating mode.
USING THE ICP CODE
This section describes the ICP code listing in the APPENDIX: Code Listing.
After a reset, the value in the reset vector $FFFE:$FFFF points to $F800, the
start of the ICP program. Once initialization has completed, the ICP code
checks for conditions for entry into normal mode (the user code) or ICP mode
(the ICP code).
JB8 will enter ICP mode when:
• The high byte of the pseudo reset vector ($FF7C) is invalid; i.e. it is not
in range of the user FLASH area ($DC to $F7); or
• The ICP_FLAG word is not a checksum.
If neither of the two conditions is true, then JB8 enters normal operating mode.
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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