This app works with an FTDI Serial-USB adapter cable and allows an Android phone or tablet recording serial data.
There is no particular requirement on the serial data other than it must be ASCII text and each record must be terminated with a carriage return-line feed.The example picture above shows recording GPS data from a NEO-6M GPS module feeding an FTDI Serial-USB adapter that is in turn plugged into an Android phone running the app.
The app supports multiple baud rates. At the moment there are 3 options but that can easily be extended if other settings were required.
When you start a new recording session (by clicking Start), the first piece of data that is saved is the time and date so you know when the recording started.
When you click Save, the data stored in the scrolling window is saved to a file. The file name is "USB Logger" followed by the time and date at the time the file is saved (so you know when recording finished) followed by ".log".
Once the data is saved to the file, the scrolling window is cleared and the date/time added to the top again. So you can save the data in chunks so that the files don't get too big and stitch it back together in one big file in the PC if you need to.
If you collect a lot of data without saving and the tablet runs out of RAM, you will get a warning a little bit before everything crashes so that you can save the data. Once you save the data, it frees the memory so you have a fresh start. It is very likely that you will run out of battery before you run out of RAM but it depends on the tablets. Some cheap ones don't have much RAM. You may need to experiment to find out how often you need to save.
To copy the data to a PC, you need to connect the tablet to the PC with a USB cable. The tablet should appear as a USB flash drive in the PC's File Explorer. Tablets do not always save the data in the same place in their filesystem (depends on Android version and manufacturer) so you may need to search a little bit but it will be in a folder named "USB Logger" and the file name starts with "USB Logger", followed by date and time and terminated with ".log"
It is a text file that you can open with Notepad for instance on the PC and use for further processing.