Keep DTR/RTS high during DFU

[alien]

Hi guys:

Right now I have my custom board using nRF52833.

I wang to use DFU over uart to upgrade firmware.

I try a different way to enter DFU mode, and this require DTR stay low during the whole precess.

Can this  achieved by modifying the code in nrfutil python script or bootloader?

Thanks in advance!

[alien]

Also I disabled Flow Control in bootloader.

[Edvin]

Hello,

During a DFU process, the nRF is reset at least once. A successfull DFU usually has 2-3 resets depending on what SDK you are using (nRF5 SDK or nRF Connect SDK).

During a reset, there is no way to keep a pin as an output. You can set it immediately after the reset, but there will be a small gap. If that doesn't work for you, you would need to use an external pullup or pulldown resistor. That is unfortunately the only way to keep GPIO states while resetting the nRF. 

Best regards,

Edvin

[alien]

Hi Edvin,

Thanks for your reply.

Since I individually have an usb-serial pcb board. The DTR/RTS will keep high when there is no data transport on TXD/RXD. During the DFU process, DTR/RTS will become low before the DFU finished.  I just want to know if I can always let DTR/RTS stay high on this usb-serial pcb board.

Alien

[Edvin]

Hello Alien,

So you are saying that your usb-serial pcb already pulls up the DTR/RTS? 

[alien]

Hi Edvin,

Yes,when it pluged in my computer, the DTR/RTS stay high.

Alien