Hi @Nicolás Martinez ,
I believe that the easiest way to acquire the timestamp is to configure the related input in the Expert mode option of the smartphone app ST BLE Sensor, as shown in the picture below:
If you otherwise want to set the board by code programming, you can use the DataLogExtended application that you can find in the FP-SNS-STBOX1 in the Projects folder (\Projects\STM32L4R9ZI-SensorTile.box\Applications\DataLogExtended:( it allows also the acquisition of the data and the timestamp with the Unicleo-GUI (via USB or BLE). The driver dedicated to the RTC is in the Drivers folder (\Drivers\STM32L4xx_HAL_Driver).
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-Eleon