How to upload firmware on custom board with brand new nRF52840

[Salvo]

Hi,

i'm new on using nRF5 modules and i have some question about how to program the nRF52840 on a custom board, so with a completely new chip.

Reading the schematic of the nRF52840 Dongle i understand that the device is flashed directly connected to the USB of the PC, but reading a forum and information on the infoCenter, i understand that it is possible to becouse the dongle arrives with a pre-programmed bootloader, that allows flashing firmware via USB.

Now I'm asking: if I have the necessity to make a custom board with a brand new nRF52840, what do I have to take care about during the schematic design in terms of connector and pins necessary to flash the device? I need the SW interface? If yes, I will have to use another external programmer until I will flash a bootloader that enables for the USB programming mode, it is?

Thanks in advance.

Salvo.

[Salvo]

Thanks MaAtevz and nar_tri for your answers, they are very useful.

I'm interested in programming the custom board with a nRF52 DK, becouse of the very out of budget Segger jlink programmer. So now i'm asking: is it possibile to flash a brand new nRF52840 with any DK like a nRF52840 dongle (PCA10059), which has a connector with SWIO and SWDCLK pins (J2 connector), or i need the bigger one DK like the PCA10056?

If i buy two nRF52840 Dongle, could i flash one dongle with the other with the same procedure i will use with my future custom board? I'm asking just to know if i can do some practice with this procedure. 

Edit:
I read about the DFU mode to program the nRF52840, but this mode requires the presence of a bootloader inside the nRF chip, is it correct? And this bootloader for the DFU mode is not inside a virgin nRF52840 module, right?

Thanks a lot, this forum is great!

Salvo

[Matevz B]

I think the P1 and J2 ports on PCA10059 are only used to program the 52840 SOC on it. nRF52 DK (PCA10040) and nrRF52840 DK (PCA 10056) have additional hardware and ports (P19 and P20 on 52) to program other boards.

I think you are correct about the DFU, but I don't have experience with it.

[Salvo]

Yes, you are right about P1 and J2 connector. I will take a PCA10056 for testing and to be able to flash whatever nRF SoC.

Thanks a lot for the help.