April 2013 DocID024207 Rev 1 1/11
AN4246
Application note
Proprietary Code Read Out Protection
on STM32L1 microcontrollers
Introduction
The protection of the intellectual property of embedded code has become a high importance issue
concerning the microcontrolle rs. In order to provide this protection, STM32 microcontrollers have
diff erent means of protecting Flash code against copy and reverse engineering.
This application note describes the generic STM32 family Flash protection features. The focus is on the
Proprietary Code Read Out Protection (PCROP) which is embedded in medium-density plus
STM32L151xC, STM32L152xC, STM32L162xC and STM32L100xC microcontrollers.
Table 1 lists the microcontrollers concerned by this application note.
Table 1. Applicable products
Type Applicable products
Microcontrollers STM32L1 (STM32L151xC, STM32L152xC, STM32L162xC and STM32L100xC)
www.st.com
Contents AN4246
2/11 DocID024207 Rev 1
Contents
1 Flash code protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Global Read Out Protection (RDP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Write Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Proprietary Code Read Out Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Secure Firmware Update (SFU) bootloader protection . . . . . . . . . . . . . . . 7
2.2 Preloaded third-party IP code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Reference documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
