cortex-m0加密

　　Code Read Protection is a mechanism that allows users to enable different levels of

　　security in the system so they can protect both their software code and hardware.

　　LPC1100/LPC1300 devices have three different active security levels： CRP1， CRP2， and

　　CRP3. Each mode increases the security level， with CRP3 restricting any access to the

　　device. These devices also feature a new protection level “NO_ISP” which will suppress

　　response to the ISP pin at system startup （but will not prevent debug via SWD， nor will it

　　prevent read access to flash memory）。 In this application note we examine all these

　　security levels and how to use them according to various security requirements. We also

　　provide an example to test all of these modes. This application note will make use of the

　　LPCXpresso1114 or LPCXpresso1343 Evaluation boards and the LPCXpresso

　　Baseboard. The software will be developed using the LPCXpresso IDE.

　　CAUTION： Although the example used in this application note was carefully tested，

　　it is recommended that the user initially configure the device to a level lower than

　　CRP3. Once the code is successfully tested， CRP3 can be used with confidence.