A typical embedded system has no security structure. If a hacker breaks in anywhere he has access everywhere — to the keys, critical data, and everything. Secure coding is a great thing to do, but it only takes a single flaw to compromise the whole system, and on a system with thousands of lines of code, it could take a long time to find and fix all problems. It’s a never ending battle because new exploits are conceived continually. Partitioning greatly limits the scope of an intrusion and allows focusing secure coding efforts on the most critical partitions. This talk focuses on use of the Cortex-M Memory Protection Unit to partition the application and RTOS for security. After introducing the MPU and partitioning briefly, it discusses novel techniques at a fairly detailed level. It shows the mechanics with code and build file snippets.