DAP - Debug access port flexibility

[Deepspace]

I am new to the nRF52840 and the whole Nordic environment, so this may be a pretty basic question. I couldn't find any other blog entries that fit.

I am developing a manufacturing PCBA level test for a nRF52840 based product. We are developing custom firmware for this mfg test. The only port that I have access to without building a bed-of-nails fixture is the  DAP - Debug access port.

Can the  DAP - Debug access port be configured as a standard serial or I2C port, etc.? Can I send commands over this port and get responses back if my firmware supports that?

I'm not sure of the restrictions on using the  DAP - Debug access port, and reading the documentation and web searches have not answered this question.

Thanks so much for your help.

[Jørgen Holmefjord]

Hi,

From the product specification:

The debug access port (DAP) implements a standard ARM CoreSight serial wire debug port (SW-DP), which implements the serial wire debug protocol (SWD). SWD is a two-pin serial interface, see SWDCLK and SWDIO in Debug and trace overview.

The SWDCLK and SWDIO pins does not have GPIO functionality, as you can see in Pin assignments. These pins can therefore not be used for standard serial or I2C ports.

The DAP/SWD can support things like reading/writing memory (Flash/RAM/peripheral registers, etc) and control the CPU. We provide support for Segger RTT, which works similar to a serial interface to the chip over the SWD interface. This can be used as a backend for the Zephyr Shell to send and received commands to and from the device, or for the Logger module to receive logs from the device.

Best regards,
Jørgen