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.
| 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.