SAM L11 Debug Access Level

Debug Access Level Overview

The SAM L11 has the following configurable Debug Access Levels (DAL), which restrict programming and debug access to Secure and Non-Secure resources in the system:

  • DAL2: Debug access with no restrictions in terms of memory and peripheral accesses.
  • DAL1: Access is limited to the Non-Secure memory regions. Secure memory region accesses are forbidden.
  • DAL0: No access is authorized except with a debugger using the Boot ROM Interactive mode.

The DAL is combined with three key-protected ChipErase commands, which provide three levels of Non-Volatile Memory erase granularity as shown in the figure below.

saml11-dal.png

Dual-Developer Approach

In this approach, the first developer (Customer A) is in charge of developing the Secure application and its associated Non-Secure Callable (NSC) library (.lib/.h), and providing a predefined linker file to the second developer (Customer B). This Secure application is then loaded in the SAM L11 Flash and protected using the set DAL1 command to prevent further access to the Secure memory region of the device.

A second developer (Customer B) will then start his/her development on a preprogrammed SAM L11 with limited access to Secure resources (call to Non-Secure API only). To achieve this, Customer B will use a linker file and the NSC library provided by customer A. The figure below illustrates a dual developer approach on SAM L11.

saml11-dal_dual_dev.png
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