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Topic: Transform Severino 5v to 3.3v (Read 1 time) previous topic - next topic


As you could probably be thinking, I need to connect an SD card to Arduino Severino. The thing is Severino has no 3.3v pin, so I need to transform that 5v power to 3.3v for the SD card. Can anyone tell me wich materials shoud I buy and how do I connect them?

Thank you for your help.

Notice that I have no electronics knowladge at all.


Notice that I have no electronics knowladge at all.

Then you should by a SD shield that does the level conversion.
The art of getting good answers lies in asking good questions.


Change the 5V regulator to a 3.3V regulator, the crystal to 8 MHz, reload the bootloader to match.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.


I bought a hex buffer for the i/o pins and use a 3.3v regulator on the 5v out pin and plug the regulated 3.3v into the the VDD of the sd card this way you will not have to desolder any parts and you don't have to run your arudino at half speed.


Interesting. Plugging a SD card was for logging an access control, but it seems that reading users in an SD card could be very slow (I've been reading about that topic.) But it would be nice to know how to get 3.3v. Can you provide a schematic and values? As I said before, I have no knowladge of electronics. I'm learning.


Apr 17, 2012, 04:43 am Last Edit: Apr 17, 2012, 04:45 am by Mr_arduino Reason: 1
I have a picutre:Note this also interfaces with a spi ram chip I am using 2 chip select pins (one for sd card and one for ram chip) to select ram chip or sd card.

and an extremely hard to follow drawing
Code: [Select]

Sd card to arudiono
I am using the arduino uno r3 it should be the same on all revisions though
       |                                       |
       | ooooooooooooooooooooooooooooooooooooo |
       | o zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz  o |
       | o z dddddddddddddddddddddddddddddzd o |
       | o z d aaaaaaaaaaaaaaaaaaaaaaaaaa zd o |
________|_o_z_d_a_______________________ a zd o |
|     F D 3 2 1 0 9 8  7 6 5 4 3 2 1 0  |a zd o |
|     E N 1 1 1 1 ~      ~ ~   ~        |a zd o |
|     R G     ~ ~                  X X  |a zd o |
|     A         Digital (PWM~)     T R  |a zd o |
|  Arduino Uno                          |a zd o |
|                                       |a zd o |
|   F T                                 |a zd o |
|   E E 3                               |a zd o |
|   R S .                               |a zd o |
|   0 E 3                               |a zd o |
|   I R V                               |a zd o |
¯¯¯¯¯¯¯¯3¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯a zd o |
       3zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzazzd o
    aaa3aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa  d o |                              
    a  C3333333333333333333            ooooooo |
  bbabb3bbbb  C___________3____________o___d___C
33b33333z  bbb|bbbbbbbbbbb3bb          o   d   |
3 b a   z yyyy|yyyyyyyyy               o   d   |
_3_b_a___z_y___|________ y 3 b          o   d   |
|1 2 3 4 5 6 7 8        |y 3 b          o   d   |
|  HEF4050B             |y 3 b          o   d   |
|                       |y 3 b          o   d   |
|9 10 11 12 13 14 15 16 |y 3 b          o   d   |
¯o¯¯*¯¯¯¯¯¯¯¯¯¯q¯¯d¯¯¯¯¯ y 3 b          o   d   |
o  *        qqq  dddddddYd3dbddddddddddodddd   |
yoyy*yyyyyyyyyyyyyyyyyyyyy 3 b          o       |
yo  *        q             3 b          o       |
yooo*oooooooooooooooooooooo3ooooooooooooo       |
yy  *** 33333333333333333333 b                  |
ybbbb*b3bbbbbbbbbbbbbbbbbbbbb                  |
yb   * 3    q                                  |(GND is connected to sd pins 3 and 6 that part appears to be slightly diffucult to see)
yb  3*33    q                                  |
 by|3*|qqqqqq   NOTE IMPORTAN READ ME!!!!!!:even though some of the
_by|3*|q_      Wires appear to be connected to another wire because they are touching another wire they are not connected they are overlapping
/912345678|     also some wire were they "overlap" appear to be broken they are NOT
|         |     This is due to 2d limitations to solve this I will write were it is connected by using something like this (Uppercase C)
|         |     After finishing this I  realized alot of wires ended up overlapping                             C_C
|  SD     |     you may have to look around to find were it goes                                                | |
|         |     Two wires overlapping
|         |     AAAAAABAAAAAAA
|_________|           B
Sd pin notes
9 unused
8 also unused
3 GND1
6 GND2
5 Clock
4 supply power (3.3v)
1 cip dection (goes to pin 10 on arduino)
HEF4050B pin notes:
VDD 1 supply voltage
1Y to 6Y 2, 4, 6, 10, 12, 15 output
1A to 6A 3, 5, 7, 9, 11, 14, input
VSS 8 ground supply voltage
n.c. 13, 16 not connected
Aurduino uno pin notes:
Pin 11 MOSI Master Out Slave In
Pin 12 Master In Slave Out (MISO)
Pin 13 is the Serial Clock
Pin 10 Slave Select pin

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