nrfjprog in a daisy chain

[Dash]

When a Jlink programmer is connected to multiple devices (daisy chained) how do I specify which device is being programmed on the command line using nrfjprog?

Additionally, if I have two nrf52DK boards connected simultaneously I can get the serial numbers of each debugger using the nrfjprog -i option. How can I specify which serial number I want to use for programming operations using nrfjprog?

[Sigurd]

Hi,

You can use the -s command to select the debugger you want to use. From the documentation :

-s --snr <serial_number> Selects the debugger with the given serial number among all debuggers connected to the computer for the operation. Must be combined with another command.

[Sigurd]

Normally daisy chaining programming allows you to connected several chips/devices to a single programming interface, and then program them all at once.

Q: How does the SWD know which nrf52 device it is programming since there is one on the nrf52DK and one on the thingy52?

A: When you have connected another device to the Debug out port (P19 or P20) on the nRF52-DK, the Segger J-Link OB debugger on the nRF52-DK will detect the supply voltage of the board and program/debug the target chip on the external board instead of the on-board nRF52832.

If you are interested in production programming, we have a white paper on that here.