problem with microSD and DFplayer mini

Other Hardware Audio
1

hi
i have 10 microSD 8-GigaByte brand BlackPCS for use with mp3 DFplayer mini.

al micro SD are FAT32 and work well on computer and MP3 files.
all microSD are new
all microSD store the same mp3 files
using library DFRobotDFPlayerMini.h

problem is: only 3 microSD work on DFplayer. The rest gives error initiating DFplayer:

Unable to begin:
1.Please recheck the connection!
2.Please insert the SD card!

i have tried:

FAT32 Reformat the not-working microSD. Even change the allocation unit size
also inspected properties for both working vs not-working and are equal

any help?

2

You don't have a wiring diagram nor do I know if which Arduino you are using, but check those RX/TX lines first- make sure BOTH of them have a resistor. Also assuming you are using Dupont wires- check those connections and make sure they're ok and not bent. I will also give my standard answer to NOT use the DfMiniPlayer Library and instead use PowerBroker2's DF Mini Fast Library in the Arduino IDE Libraries downloadable section- a much cleaner and easier to use library. Make sure the example works.