NRF52840 and USB circuit board

[learning101]

Hello Support team,

I'm working on a project where I am designing a custom board uisng the Nordic NRF52840 as the MCU (forgive me if I'm using the incorrect terminology or decripition for things as I am new to all this). Essentially, I want to be able to program and update the MCU through a USB. For my design, I am using a generic 4 pin 2.0 USB and have made the necessary conenctions to an FTDI (FT232RL) in order to convert from USB to serial. Now I am unsure of the connections I need to make from the FTDI to the NRF52840, such as which pins the RX and TX should go. I'm not even sure if this design will work with the chip, but it is a method of used in the past for another project. I would appreciate it if y'all could point me in the right direction.

Thank you.

[David Fogelsong]

The good news for you is that the nRF52840 has usb built into the actual chip itself.    However, I suspect (?) it doesn't work automatically, without initialization, like an FT232RL would.

[Einar Thorsrud]

That is correct. the nRF52840 ships with an empty flash, so you need to program it via SWD initially. If you program it with a USB bootloader, then you can subsequently use USB for later programming. The Open bootloader example in the SDK can be used for this.