nRF52840 Dongle programming for Windows

[EdwinP]

I need to write a Windows program that talks to the nRF52840 Dongle.  Is there a .dll or .lib or source code for communicating with the Dongle?  I have programmed the dongle with s140_nrf52_6.1.0_softdevice.hex.  I can not find any documentation of the actual interface that is seen on the PC.  Is it just operated via commands over the COM port?  Are these commands documented?  Where can I find this documentation?

I also need an application to use the nRF52840 Dongle in a pass-through UART mode.  Do I need to load a different hex file into it for that?  Where can I get that?  Is there documentation of the GATT service and characteristic UUIDs for this code?

Thanks!

[EdwinP]

More: I found the GATT definitions for ble_app_uart, which looks like the code I need for the pass-through mode.  Can I program ble_app_uart_pca10056_s140.hex into the PCA10059 dongle?  How do I do that?  I tried using nrfutil, but it would not program my dongle.

I tried these commands to build a package and then program the dongle:

nrfutil pkg generate --hw-version 52 --application-version 4 --sd-req 0xA9 --application ble_app_uart_pca10056_s140.hex app_dfu_package.zip

nrfutil dfu serial -pkg app_dfu_package.zip -p COM4 -b 115200

Is there a package I can download for this?