Purpose of Interface MCU on nRF7002

[Michael Zeng]

Is the purpose of the Interface MCU on the nrf7002dk to act as a programmer for the main nrf5340 MCU?

Is there anything preventing the use of the secondary USB port (the one labeled "nRF USB") to program the main nrf5340 MCU? What is this USB port for?

When designing a custom PCB with both the nrf5340 and nrf7002, can the Interface MCU be omitted from the PCB? If so, to program the main nrf5340 MCU, could we use an nrf7002dk as a programmer that connects to the custom PCB?

I also see in the nrf7002dk schematic that the primary connections between the Interface MCU and the main nrf5340 MCU are VCOM0, VCOM1, and SWD3. Are all three of these necessary to program the main nrf5340 MCU? Or could just the SWD3 be used (and we can remove the VCOM0 and VCOM1 connections)?

Final question--can the VBUS pin on the main nrf5340 MCU just be grounded if the "nRF USB" port is not used?

Thank you, and please let me know if any of those questions were not clear!

[Michael Zeng]

In addition, what is the purpose of the SWD0 and SWD1 connectors? According to the nrf7002dk schematic, both of these connect to the the interface MCU GPIO pins. What is the purpose of each of these and what is the difference between the 2? 

[haakonsh]

Is the purpose of the Interface MCU on the nrf7002dk to act as a programmer for the main nrf5340 MCU?

Yes, it is just a debugger that happens to be another nRF5340. It runs J-Link debugger FW from SEGGER.

Is there anything preventing the use of the secondary USB port (the one labeled "nRF USB") to program the main nrf5340 MCU? What is this USB port for?

If the main nRF5340 has a bootloader programmed, then you can do DFU over 'nRF USB'. 

When designing a custom PCB with both the nrf5340 and nrf7002, can the Interface MCU be omitted from the PCB? If so, to program the main nrf5340 MCU, could we use an nrf7002dk as a programmer that connects to the custom PCB?

Yes, to both questions.

I also see in the nrf7002dk schematic that the primary connections between the Interface MCU and the main nrf5340 MCU are VCOM0, VCOM1, and SWD3. Are all three of these necessary to program the main nrf5340 MCU? Or could just the SWD3 be used (and we can remove the VCOM0 and VCOM1 connections)?

You only need SWDIO, SWDCLK, VDD, and GND, in order to use the SWD interface. VCOM are not needed.

Final question--can the VBUS pin on the main nrf5340 MCU just be grounded if the "nRF USB" port is not used?

Yes. DECUSB and D+/- can be NC.

Michael Zeng said:

In addition, what is the purpose of the SWD0 and SWD1 connectors? According to the nrf7002dk schematic, both of these connect to the the interface MCU GPIO pins. What is the purpose of each of these and what is the difference between the 2? 

The difference is that SWD0 needs a specific 10-pin connector, whereas SWD1 can use any set of board-to-board jumper wires.
Also, SWD1 and the GPIO pin headers on the DK supports Arduino shields.