Pin interface and factory programming nRF52840 over UART connected with processor

Question

Hi, 
 I have arm based application processor and need to connect with nRF52840 using UART, I don't have any idea about bootloader and factory firmware when hardware assemble. 
 1) What is pin connection required to connect with application processor to factory program nrf52840(new module without any firmware) via UART? without Seggar debugger/programmer. 
 2) If firmware flash is possible via UART, which pin required to put nRF52840 in booting mode? 
 3) Is DFU example is enough to do factory firmware update which is given in SDK nRF5_SDK_15.0.0_a53641a? 
 Thanks

RK · Accepted Answer

again no - the chip comes from the factory entirely blank it has NOTHING on it. You have to do the initial programming via SWD (or have the factory do it). 
 And OTA means 'over the air' so you wouldn't do OTA via UART, you'd do OTA via bluetooth. And to do that you need to have first put a bootloader/softdevice etc on the chip via SWD.

Einar Thorsrud · Answer

Hi, 
 
 There is no bootloader on the nRF5 devices. They are shipped with an empty flash. This means that you must program the device with a bootloader via SWD before you can program it via UART. 
 You can configure any GPIO's you like for UART communication with the host processor when you configure and build the bootloader. 
 Yes, provided that you initially program the bootloader via SWD. You can refer to the Secure DFU Bootloader over Serial Link (UART/USB) example.

Pin interface and factory programming nRF52840 over UART connected with processor

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