Product Specs

16 Debug and trace
Page
73
16.2 CTRL-AP - Control Access Port
The Control Access Port (CTRL-AP) is a custom access port that enables control of the device even if the
other access ports in the DAP are being disabled by the access port protection.
Access port protection blocks the debugger from read and write access to all CPU registers and memory-
mapped addresses. See the UICR register APPROTECT on page 66 for more information about enabling
access port protection.
This access port enables the following features:
• Soft reset, see Reset on page 82 for more information
• Disable access port protection
Access port protection can only be disabled by issuing an ERASEALL command via CTRL-AP. This
command will erase the Flash, UICR, and RAM.
16.2.1 Registers
Table 21: Register Overview
Register
Offset
Description
RESET
0x000
Soft reset triggered through CTRL-AP
ERASEALL
0x004
Erase all
ERASEALLSTATUS
0x008
Status register for the ERASEALL operation
APPROTECTSTATUS
0x00C
Status register for access port protection
IDR
0x0FC
CTRL-AP Identification Register, IDR
RESET
Address offset: 0x000
Soft reset triggered through CTRL-AP
Bit number
Id
Reset 0x00000000
31 30
0 0
29
0
28
0
27
0
26
0
25
0
24
0
23 22 21 20
0 0 0 0
19
0
18
0
17
0
16
0
15
0
14
0
13
0
12
0
11
0
10
0
9
0
8
0
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
A
0
Id RW Field
Value Id
Value
Description
A RW RESET
Soft reset triggered through CTRL-AP. See Reset Behaviour in
POWER chapter for more details.
NoReset
0
Reset is not active
Reset
1
Reset is active. Device is held in reset
ERASEALL
Address offset: 0x004
Erase all
Bit number
Id
Reset 0x00000000
31 30
0 0
29
0
28
0
27
0
26
0
25
0
24
0
23 22 21 20
0 0 0 0
19
0
18
0
17
0
16
0
15
0
14
0
13
0
12
0
11
0
10
0
9
0
8
0
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
A
0
Id RW Field
Value Id
Value
Description
A W ERASEALL
Erase all FLASH and RAM
NoOperation
0
No operation
Erase
1
Erase all FLASH and RAM
ERASEALLSTATUS
Address offset: 0x008
Status register for the ERASEALL operation