SD Drive for Atari 8-bit with few hardware changes: 

• no more SD CARD NOT DETECTED - AVR and SD card talk to each other with no odd resistor dividers - just direct connection with SPI communication made the proper way
• AVR runs at 3v3
• tiny AVR in QFN package, thus 14MHz at 3v3 possible and real
• 402 SMD elements used
• level shifting between SIO and AVR removed! Atari reads 3v3 at SIO port 

Buttons and LEDs  

• Pressing left button selects next drive (D1: -> D2: -> D3: -> D4:)
• Pressing right button cycles through drives in opposite direction
• 2 buttons pressed together - resets the device; loader contained in SDRIVE.ATR will load after next Atari reset
• 6 LEDs indicate as follows:
  • two red ones indicate SD card activity and error
  • another 4 LEDS indicate selected drive: D1: PINK, D2: BLUE, D3: GREEN, D4: ORANGE

		`
PINK	BLUE	GREEN	ORANGE
Slot D1: selected and used as Atari disk drive no 1.	Slot D2: selected and used as Atari disk drive no 1.	Slot D3: selected and used as Atari disk drive no 1.	Slot D4: selected and used as Atari disk drive no 1.

How to use?

• Get decent microSD card
• Format it to FAT32
• Put SDRIVE.ATR file on it
• Put also some games and demos. You can use subfolders
• Insert SD card into the SD Drive Mini
• Connect it to Atari SIO port and power on
• All LEDS should power on creating white coloured light
• Red LED shall blink once indicating that the SD card has been detected
• Choose files you want and assign them to drives D1: -> D4: slots using Tab, cursors and Return
• Reset the Atari
• File assigned to D1: shall load (remember to hold Option to disable Basic if required)
• To select another slot press left and right buttons - device will indicate which slot is active with proper colour. Reset your Atari again
• To start file selector again (SDRIVE.ATR), reset SD Drive Mini by holding both buttons on the device and then reset Atari