It uses BLE, so no UART is involved. Do you want to talk to something using the charging cable?
I m using the CIQPI source code used in the link you ve sent me (on my watch side) and i need to send a json file to a raspberry.
On the raspberry PI i m using a code that creates a GATT server and sends data via uart:
https://scribles.net/creating-ble-gatt-server-uart-service-on-raspberry-pi/
i ve tested as shown in the link the connexion with the APP NRF toolbox (IT works perfectly)
I would ve liked to know if it would work with a garmin app ( is UART compatible)
Thanks in advance for your answer!
See the programmer's guid and https://forums.garmin.com/developer/connect-iq/w/wiki/19/getting-started-with-connect-iq-ble-development for setting up the CIQ sim for BLE. It's much easier than trying to test on a devive.
In the interface to the pi, I use nodejs.
The CIQ end doesn't handle sending files - that would be something you'd need to add (likely sending the file in pieces). If you want to send files, maybe look at setting up a web server on the pi and use makeWebRequest? You'll want to use https.