Add important notes about CMSIS

Author: felipe-iar

NOTES.md

@@ -0,0 +1,25 @@
+## Important Notes
+
+### Updated CMSIS headers
+CMSIS, or Cortex Microcontroller Software Interface Standard, consists of a vendor-independent hardware abstraction layer for Arm Cortex processors which provides consistent device support. Developed by Arm, it provides simple software interfaces to the processor and the peripherals, simplifying software re-use, reducing the learning curve for developers, and reducing the time to market for new devices.
+
+Some of the example projects use legacy versions of CMSIS. If when building a project requiring them, you might face a fatal error such as:
+
+>Fatal Error[Pe1696]: cannot open source file “core_cm3.h”
+
+The recommended solution is to use `git` for fetching the required CMSIS headers:
+* Linux (as root):
+```
+cd /opt/iar/
+git clone https://github.com/arm-software/cmsis_5
+cd ewarm/arm
+ln -s ../../cmsis_5/CMSIS
+```
+* Windows (Administrative Command Prompt):
+```
+cd /iar/
+git clone https://github.com/arm-software/cmsis_5
+mklink -d ewarm-10.xx.x ewarm
+cd ewarm/arm
+mklink -d ../../cmsis_5/CMSIS
+```

README.md

@@ -2,6 +2,9 @@
 
 This repository offers a compendium of links to device vendor repositories with example projects.
 
+>[!IMPORTANT]
+>See [important notes](NOTES.md)
+
 ## Quick Navigation
 - [Arm example projects](#for-arm)
 - [RISC-V example projects](#for-risc-v)