I tried with a powered USB hub (UGreen), a USB 3 card reader (UGreen) and a USB SSD, an Iphone, SE, an older Google Pixel and a very old LG Android. It worked for the IPhone and the LG, but not for the Pixel. It is a little bit of trial and error. Main problem was the transfer speed of roundabout 1 MB/s. My solution is a Raspberry Pi 5 and less than 100 lines of Python code and a breadboard soldered with 4 LEDs for status indication (yellow program started, blue source connected, red target connected and copy started, green completed). Transfer speed is 80 MB/s, which is what the MicroSD card can deliver. It's a small package, see picture.
A more advanced solution based on the Pi 5 is the Little Backup Box which can be operated via the Smartphone. If you consider one of osmonauta‘s suggestions, please check whether they can synchronize only newer files or always do a full copy (which will waste a lot of space on the SSD). And when selecting an USB hub I would look for a hub with a Power/Data PD port so your smartphone is charged during the copy process. |