1.3 Register Bit Types

The following table describes the register bit attributes used throughout this document.

Table 1-3. Register Bit Types
Register Bit Type NotationRegister Bit Description
RRead: A register or bit with this attribute can be read.
WWrite: A register or bit with this attribute can be written.
RORead Only: A register or bit with this attribute is read only; writing has no effect.
RCRead to Clear: Content is cleared after the read. Writes have no effect.
SCSelf Clearing: A bit with this attribute will be cleared to ‘0’ after being written as ‘1’. Hardware often clears such bits following the completion of some action initiated by the write.
NASRNot Affected by Software Reset: The state of NASR bits do not change on assertion of a software reset.

Many of these register bit notations can be combined. Some examples of this are:

  • R/W: Can be written. Will return current setting on a read.
  • R/W SC: Bit is readable. When set, it will automatically be cleared by hardware once some action is complete.
  • R/W1C: Bit is readable. Write a ‘1’ to this bit to clear.