Merge pull request #3801 from raspberrypi/anchor-points-for-paul

Add architecture switching and security sections, to be built out more in future

documentation/asciidoc/microcontrollers/silicon/rp2350.adoc

@@ -45,6 +45,18 @@ Key features include:
 ** USB 1.1 controller and PHY, with host and device support
 ** 3 Programmable IO (PIO) blocks, 12 state machines total
 
+==== Security
+
+RP2350 has a comprehensive security architecture, built around Arm TrustZone for Cortex-M, including the following features:
+
+* Signed boot support
+* 8KB of on-chip antifuse one-time-programmable (OTP) memory
+* SHA-256 acceleration
+* A hardware true random number generator (TRNG)
+
+==== Architecture Switching
+
+RP2350 includes a pair of open-hardware Hazard3 RISC-V cores which can be substituted at boot time for the Cortex-M33 cores. Our boot ROM can even auto-detect the architecture for which a second-stage binary has been built and reboot the chip into the appropriate mode. All features of the chip, apart from a handful of security features, and the double-precision floating-point accelerator, are available in RISC-V mode.
 
 === RP2350-based Boards