9.1.2 Registers Access Permissions

Each Peripheral has different register access permissions depending on the following:
  • Its PAC Security Attribution (Secure or Non-Secure)
  • If it is a Mix-Secure Peripheral: PORT, EIC
  • If it is an Always Secure Peripheral: IDAU
  • If it is an Always Non-Secure Peripheral: DSU
Peripherals excluding Mix-Secure Peripherals case:
  • If the peripheral is configured as Non-Secure in the PAC:
    • Secure access and Non-Secure access are granted
  • If the peripheral is configured as Secure in the PAC:
    • Secure access is granted
    • Non-Secure access is discarded (Write is ignored, read 0x0) and a PAC error is triggered

Always Secure Peripheral case (IDAU) :

  • Secure access is granted
  • Non-Secure access is discarded (Write is ignored, read 0x0) and a PAC error is triggered

Always Non-Secure Peripheral case (DSU):

  • Secure access and Non-Secure access are granted
Mix-Secure Peripherals case (PORT, EIC):
  • If the peripheral is configured as Non-Secure in the PAC:
    • Secure access and Non-Secure access are granted
  • If the peripheral is configured as Secure in the PAC:
    • The peripheral behaves like a Mix-Secure peripheral

For additional information, refer to 14 Implementation Defined Attribution Unit (IDAU).