Table 12-21 Bit Assignments For The Ap Select Register, Select; Figure 12-23 Bit Assignments For The Ap Select Register, Select - ARM Cortex-M3 Technical Reference Manual

Debug Port
Bits Function
[31:24] APSEL
[23:8] -
[7:4] APBANKSEL
[3:1] -
b b
[0] CTRLSEL
a. On a SW-DP the register is write-only and therefore you cannot read the field value.
b. Implemented on SW-DP only. On a JTAG-DP this bit is Reserved, SBZ/RAZ.
12-58

Figure 12-23 Bit assignments for the AP Select Register, SELECT

Table 12-21 lists the bit functions of the Select Register.

Table 12-21 Bit assignments for the AP Select Register, SELECT

Description
Selects the current AP.
The reset value of this field is Unpredictable.
a
Reserved. SBZ/RAZ .
Selects the active four-word register window on the current AP.
The reset value of this field is Unpredictable.
a
Reserved. SBZ/RAZ .
SW-DP Debug Port address bank select, see CTRLSEL, SW-DP only on page 12-59.
After a reset this field is b0. However the register is WO and you cannot read this value.
If APSEL is set to a non-existent AP then all AP transactions return zero on reads and
are ignored on writes.
Note
Every ARM Debug Interface implementation must include at least one AP.
Copyright © 2005, 2006 ARM Limited. All rights reserved.
a
a
ARM DDI 0337B