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问 为什么我设置成禁止其他区读写后，再想设置为允许就不成功呀？
用的是引导区程序设置的。
如果软件有问题那设置禁止其他区读写的时候也应该不成功对吧？

请大侠门帮忙！谢谢
答 1: 这是对的，看看这个The application and Boot Loader section CAN be protected on different levels. There are
four levels of protection for both sections. A short description of the modes follows.
Note that once programmed (cleared), it is impossible to unprogram the bits again without
using serial or parallel programming. For instance, to implement an application that
is to be updated once, set Boot Lock mode 1 on the Application section, and mode 4 on
the Boot Loader section. This prevents the application from accessing the Boot Loader,
while giving the Boot Loader full access to update the application section. Once
updated, the Boot Loader would set mode 3 on the Application section, thus blocking all
further access.
To program the Boot Lock bits, load the R0 Register with the correct bits, set the BLBSET
and SPMEN bits in the SPMCR Register and execute the SPM instruction within
four cycles. The contents of the Z-register are ignored.
Using the LPM instruction instead of the SPM instruction will read the bits.
Table 1. Boot Lock Modes
Mode Bits Description
Mode 1 11 Full read/write access
Mode 2 10 No write access
Mode 3 00 No write access and no read access (data or interrupt execution) from the
other section.
Mode 4 01 No read access (data or interrupt execution) from the other section.

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