interfacing SD/MMC card with AVR microcontroller

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akshay985

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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
 

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
 

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...
 
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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.
 

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)
 

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