Hello,
Not a 100%, but in this Nordic video the nRF52840 might be using the Alexa Gadgets Toolkit.
Alexa Notepad demo 2020
https://www.youtube.com/watch?v=CdLfg-6kQs0
I can get the Raspberry Pi gadget samples going on an Echo Show, and now trying the same for a DK840.
https://github.com/alexa/Alexa-Gadgets-Raspberry-Pi-Samples
Using template along with the Gadget guide, I can pair the DK to the Echo, but not get Connected.
https://developer.amazon.com/en-US/docs/alexa/alexa-gadgets-toolkit/bluetooth-le-pair-connect.html
Not connected obviously because I'm not yet sending the Amazon ID and Alexa Gadget Secret to make this happen.
Here I'm not exactly sure of how to complete this connection Handshake step using the ID & Secret in Phase 4.
Maybe the gentleman in the video would have some insights on how the Handshake was coded for the 840.
very much appreciated,
thank-you,