interfacing SD/MMC card with AVR microcontroller

[akshay985]

I m working on ATmega16 and trying to interface SD/MMC card in SPI mode only
why the voltage levels drop after card is inserted

 

[ckshivaram]

your supply is getting shorted .. same problem i had ,, and i got it rectified after finding this fault

---------- Post added at 22:48 ---------- Previous post was at 22:47 ----------

which module are you using to insert the card... any readymade module or you developed it

 

[cocoloco]

what is the voltage of AVR Mcu?:grin:

if it's 3.3volts ok,if it's 5 volts,you need a 3.3v reg for sd card and put voltage divider resistor on spi line ,if your sd card was on 5 volts,may be shorted,fried...

 

[yokohama]

You must use a resistor between the mcu and the sd card or use shift level ic like HC244 or HC4050 fed with 3.3 V.

 

[ckshivaram]

give 3.3V directly to sd card and operate with 5V to controller, or use a resistor to drop 5V to 3.3, or
use 3.3V zener ( easiest solution)