I am working on a project using a SAMD21 processor and ILI9341 TFT screen. The circuit is powered by a 12VDC power supply (obviously have DC-DC stepdown converter). I also have a 3V backup battery to power the RTC in the MCU in the event of a power loss. Everything works fine except when I shut off 12V power and then turn it back on. The TFT screen goes all white, even though the processor is running, which seems obvious why.
Any suggestions how I can sense that the screen is all white, or that power has been reintroduced to the TFT screen so I can send the display information to the TFT screen again?