ARM r1p3, R4, R4F

Debug

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11.4.18 Device Power-down and Reset Control Register

The PRCR is a read/write register that controls reset and power-down related functionality.

Figure 11-14 shows the bit arrangement of the PRCR.

Figure 11-14 PRCR format

Table11-23 shows how the bit values correspond with the Device Power down and Reset

Control Register functions.

11.4.19 Device Power-down and Reset Status Register

The PRSR is a read-only register that provides information about the reset and power-down

state of the processor.

Figure 11-15 on page11-31 shows the bit arrangement of the PRSR.

a. Cortex-R4 does not implement the Security Extensions, so all the debug features are considered

secure.

31 03

Reserved

Hold internal reset

Force internal reset

No Power-down

Table11-23 PRCR functions

Bits Field Function

[31:3] Reserved Do not modify on writes. On reads, the value returns zero.

[2] Hold internal

reset

Hold internal reset bit. This bit can be used to prevent the processor from running again before

the debugger detects a power-down event and restores the state of the debug registers in the

processor. This bit does not have any effect on initial system power-up as nSYSPORESET

clears it.

0 = Do not hold internal reset on power-up or warm reset. This is the reset value.

1 = Hold the processor non-debug logic in reset on warm reset until this flag is cleared.

[1] Force

internal reset

When a 1 is written to this bit, the processor asserts the DBGRSTREQ output for four cycles.

You can connect this output to an external reset controller which, in turn, resets the processor.

[0] No

power-down

When set to 1, the DBGNOPWRDWN output signal is HIGH. This output connects to the

system power controller and is interpreted as a request to operate in emulate mode. In this mode,

the processor is not actually powered down when requested by software or hardware

handshakes. This mode is useful when debugging applications on top of working operating

systems.

0 = DBGNOPWRDWN is LOW. This is the reset value

1 = DBGNOPWRDWN is HIGH.