Functional Peripherals Registers
176
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Cortex-M4F Peripherals
2.4.7.2
DCRSR Register (Offset = DF4h) [reset = Unknown]
DCRSR is shown in
and described in
Deubg Core Register Selector Register. The purpose of the Debug Core Register Selector Register
(DCRSR) is to select the processor register to transfer data to or from. This write-only register generates a
handshake to the core to transfer data to or from Debug Core Register Data Register and the selected
register. Until this core transaction is complete, bit [16], S_REGRDY, of the DHCSR is 0. Note that writes
to this register in any size but word are Unpredictable. Note that PSR registers are fully accessible this
way, whereas some read as 0 when using MRS instructions. Note that all bits can be written, but some
combinations cause a fault when execution is resumed. Note that IT might be written and behaves as
though in an IT block.
Figure 2-84. DCRSR Register
31
30
29
28
27
26
25
24
RESERVED
w
23
22
21
20
19
18
17
16
RESERVED
REGWNR
w
w
15
14
13
12
11
10
9
8
RESERVED
w
7
6
5
4
3
2
1
0
RESERVED
REGSEL
w
w
Table 2-94. DCRSR Register Field Descriptions
Bit
Field
Type
Reset
Description
31-17
RESERVED
W
Undefined
16
REGWNR
W
Undefined
Write = 1, Read = 0
15-5
RESERVED
W
Undefined
4-0
REGSEL
W
Undefined
Register select
0b (R/W) = R0
1b (R/W) = R1
10b (R/W) = R2
11b (R/W) = R3
100b (R/W) = R4
101b (R/W) = R5
110b (R/W) = R6
111b (R/W) = R7
1000b (R/W) = R8
1001b (R/W) = R9
1010b (R/W) = R10
1011b (R/W) = R11
1100b (R/W) = R12
1101b (R/W) = Current SP
1110b (R/W) = LR
1111b (R/W) = DebugReturnAddress
10000b (R/W) = xPSR/flags, execution state information, and
exception number
10001b (R/W) = MSP (Main SP)
10010b (R/W) = PSP (Process SP)
10100b (R/W) = CONTROL bits [31:24], FAULTMASK bits [23:16],
BASEPRI bits [15:8], PRIMASK bits [7:0]