ARM ARM DUI 0224I

Programmer’s Reference

4.3.8 Flag registers, SYS_FLAGx and SYS_NVFLAGx

The registers shown in Table4-10 provide two 32-bit register locations containing

general-purpose flags. You can assign any meaning to the flags.

The PB926EJ-S provides two distinct types of flag registers:

• The SYS_FLAGS Register is cleared by a normal reset, such as a reset caused by

pressing the reset button.

• The SYS_NVFLAGS Register retains its contents after a normal reset and is only

cleared by a Powe r-On Res et (POR).

Flag and Nonvolatile Flag Registers

The SYS_FLAGS and SYS_NVFLAGS registers contain the current state of the flags.

Flag and Nonvolatile Flag Set Registers

The SYS_FLAGSSET and SYS_NVFLAGSSET registers are used to set bits in the

SYS_FLAGS and SYS_NVFLAGS registers:

• write 1 to SET the associated flag

• write 0 to leave the associated flag unchanged.

Flag and Nonvolatile Flag Clear Registers

Use the SYS_FLAGSCLR and SYS_NVFLAGSCLR registers to clear bits in

SYS_FLAGS and SYS_NVFLAGS:

• write 1 to CLEAR the associated flag

• write 0 to leave the associated flag unchanged.

Table4-10 Flag registers

SYS_FLAGS

0x10000030

Read Reset Flag register

SYS_FLAGSSET

0x10000030

Write Reset Flag Set register

SYS_FLAGSCLR

0x10000034

Write Reset Flag Clear register

SYS_NVFLAGS

0x10000038

Read POR Nonvolatile Flag register

SYS_NVFLAGSSET

0x10000038

Write POR Nonvolatile Flag Set register

SYS_NVFLAGSCLR

0x1000003C

Write POR Nonvolatile Flag Clear register