12.4.18. Device Power-down and Reset Status Register

The DBGPRSR Register characteristics are:

Purpose

Provides information about the reset and power-down state of the processor.

Usage constraints

The DBGPRSR Register is a read-only register, with reads of the register also resetting some register bits.

Configurations

Available in all processor configurations.

Attributes

Figure 12.15 shows the bit assignments.

Figure 12.15. DBGPRSR Register bit assignments

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Table 12.23 shows the bit assignments.

Table 12.23. DBGPRSR Register bit assignments

BitsNameFunction

[31:4]

-

Do not modify on writes. On reads, the value returns zero.

[3]

Sticky reset status

Sticky reset status bit. This bit is cleared on read.

0 = the processor has not been reset since the last time this register was read. This is the reset value.

1 = the processor has been reset since the last time this register was read.

This sticky bit is set to 1 when nRESETm is asserted. This bit is reset to 0 by PRESETDBGmn.

[2]

Reset status

Reset status bit:

0 = the processor is not held in reset

1 = the processor is held in reset.

This bit reads 1 when nRESETm is asserted.

[1]

Sticky power-down status[a]

Indicates if the core power domain has been powered down since the DBGPRCR was last read.

0 = the CPU has not been powered down since the last read. This is the reset value.

1 = the CPU has been powered down since the last read.

If this bit is 1:

  • The contents of the core domain debug registers have been lost and must be reprogrammed.

  • Debug-APB transactions that access core domain debug registers receive an error response.

This bit is cleared to 0 on a read.

[0]

Power-up status[a]

Indicates the status of the core power domain.

0 = the CPU is powered-down, that is, it is in Dormant or Shutdown mode. Core-domain debug registers cannot be accessed.

1 = the CPU is powered-up, that is, it is in Run or Standby mode. All debug registers can be accessed.

[a] If you are implementing a Split/Lock configuration, contact ARM for more information about the functionality of this bit.


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