I have figured out as to why the RETRODE II won't work with the Samsung S4. It's due to the type of file system that the RETRODE II uses. The S4 is extremely picky with the file type. :(
I found this out because my SD card keeps disconnecting & displaying the same errors that the RETRODE does. reads but then instantly corrupts.
But as soon as I use Samsung flash, no problem occurs.
Would explain as to why the RETRODE II controllers work but as soon as you plug a cart in, it goes haywire & throws its toys out the pram.
Perhaps this could bring the RETRODE community closer to making this device work with more phones. :D
I have the same problem on my nexus 7 2012 (Android 4.4.4) it seems Google took out support for the FAT file system which the retrode and seemingly your SD card use
Sorry I didn't reply until now, I never get notified when I get new messages.
4.4 has also seems to have made sdcard support even worse. It doesn't allow to write to the sdcard.
I still have the same "corrupted sdcard" issue on 4.3 so it may well be a kernel issue. However it does work - sort of on the Asus TF300T. As soon as it showed up in md . emu it crashed shortly there after.
It doesn't help that saves don't work, on some games nore can you copy the saves back to & forth without corruption. I had a look into a shining force srm file & it's been destroyed by the retrode & is completely unusable.