More SD problems with USBizi

Firmware updated sucessfully. Version number:


I think we may have a tracking issue on our board which is not going to help!!!

Let me investigate that and if we are still having problems I will come back

I appreciate your help and if it turns out to be a hardware problem then I am sorry to have taken your valuable time

Best regards


Here comes me eating humble pie!!!

It turns out we did have a tracking problem on the PCBs which we have now fixed and everything works perfectly.

I can only apologise for taking up valuable time but I certainly appreciate all the help we were given.

For those who also have problems with the SDCard class, I re-iterate the comments that power smoothing is important. Furthermore the constructor attempts to communicate with the card when it is instantiated but if communications are not possible then the exception is thrown so if you are seeing problems with the constructor then I would suggest that you double check the electrical connections to the socket and card.


We also have problems with sdcard. We have a 22uF cap between SD_PWR and GND. We measure 3.259V on the SD_PWR line.
We have a custom board based on EMX and the sdcard reliability is poor. About 2 boards over ten are not working due to SD card error while instantiating the persistent storage. How to control the fact that power source is not appropriate?

If you short 3.3V to SD_PWR pin then does the SD card always work?

give me 5 minutes to try that right now…

Ok test done without success. This does not seems to be a bad power sourcing (i took for the first experiment 2.8V on usb, the for the second experiment 3.3, from the linear voltage regulator available on our custom board, finally I have tested with laboratory stabilized power supply at 3.3V. Nothing work for this particular board and card.

The fact that in some boards it’s ok and on some of others not ok is very weird and difficult to diagnose

May be it can help in solving this problem:

If I plug the sdcard into a µsd to USB adapter, the card can be read wand write without any problem.