Hello,
I have not used your app to OTA before. I would like to make sure that with the app, I can authenticate with my BLE113 before sending the OTA file by sending a specified string from the mobile application to the BLE113. Is this possible with BLExplr?

Hi,
depending on your setup this can be done.
Well the OTA process how it is implemented does not support any authentication in the process itself.

You could of course write data to a particular characteristic before you start the OTA process, but the OTA process in the app cannot be modified in the way that it first sends e.g. a password to a service/characteristic you implemented and then start the OTA procedure directly.

You could do this manually. Navigate to the service/characteristic, write a passphrase to it and then navigate to the OTA service, select an OTA file and write it to the BLE113.

Regards
Michael