Debug access port

An external debugger can access the device through the debug access port (DAP).

The DAP implements a standard serial wire debug (SWD) Arm CoreSight™ protocol with a two-pin serial interface (SWDCLK and SWDIO).

The SWDIO pin has an internal pull-up resistor. The SWDCLK pin has an internal pull-down resistor.

The serial wire debug (SWD) pins can be used as GPIO pins when debugging is not active. For more information, see Pin assignments.

There are several access ports for connecting to different parts of the system, as shown in the following table.

Table 1. Access port overview
AP ID	Type	Description
0	AHB-AP	CM33 access port
2	CTRL-AP	Control access port

The AHB-AP is a standard Arm component. See the ArmCoreSight SoC-400 Technical Reference Manual for more information. The control access port (CTRL-AP) is proprietary and described in more detail in CTRL-AP — Control access port.

Debug access port registers

Register overview


Register	Offset	Description
TARGETID	0x024	The TARGETID register provides information about the target when the host is connected to a single device. The TARGETID register is accessed by a read of DP register 0x4 when the DPBANKSEL bit in the SELECT register is set to 0x2.
DLPIDR	0x034	The DLPIDR register provides information about the serial wire debug protocol version. Accessed by a read of DP register 0x4 when the DPBANKSEL bit in the SELECT register is set to 0x3.

TARGETID

Address offset: 0x024

The TARGETID register provides information about the target when the host is connected to a single device.

The TARGETID register is accessed by a read of DP register 0x4 when the DPBANKSEL bit in the SELECT register is set to 0x2.


Bit number				31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
ID				C	C	C	C	B	B	B	B	B	B	B	B	B	B	B	B					A	A	A	A	A	A	A	A	A	A	A
Reset 0x00000289				0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0	1	0	0	0	1	0	0	1
ID	R/W	Field	Value ID	Value								Description
A	R	TDESIGNER										An 11-bit code JEDEC JEP106 continuation code and identity code. The ID identifies the designer of the part.
			NordicSemi	0x144								Nordic Semiconductor ASA.
B	R	TPARTNO										Part number.
C	R	TREVISION										Target revision.

DLPIDR

Address offset: 0x034

The DLPIDR register provides information about the serial wire debug protocol version.

Accessed by a read of DP register 0x4 when the DPBANKSEL bit in the SELECT register is set to 0x3.


Bit number				31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
ID				B	B	B	B																									A	A	A	A
Reset 0x00000001				0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1
ID	R/W	Field	Value ID	Value								Description
A	R	PROTVSN										Protocol version.
			SWDPv2	1								SW protocol version 2.
B	R	TINSTANCE										Target instance.