I am using STM32F446RE in my project and as per the project requirements I need to have power on built in test, initiated built in test and continuous built in test on STM32F446RE. Please let me know how different built-in self-tests can be conducted and validated. Thanks
This is non-trivial design task, a good solution requires knowledge of your system and environment (if the self-test is not just a formality). The functional safety library linked by Jan provides building blocks for many components - in case you are ready to involve their NDAs...
Basically, you should trust the core MCU components: the internal oscillator, (part of) internal SRAM, (part of) internal flash, timers etc. and the power supply. If this is broken, the MCU won't run anything, including the self test. The built-in brownout detector can help with check of the power supply (but this is not software).
Using these resources, check remaining internal components (checksums/signatures in internal flash, other banks of internal RAM), state of well-known GPIOs, analog signals. Then important external components: external oscillator (if present), external memories. Then other complex external components (devices attached to SPI, I2C, and so on). For continuous test: enable runtime error detection (ECC, various fault detection...), measure the chip temperature. That's it, more or less.
Interesting this text that Microchip puts in the datasheets:
"Use of Microchip devices in life support and/or safety applications is entirely at the buyerís risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use."
I don't trust using products that have this type of caveat for safe applications.