My SD shield works nicely on 5v supply, but does not detect SD card on 3.3v. Could someone explain the possible reason behind this? Could you also provide a solution for this?

I've worked with it on Arduino Uno. Now I want to use SD card directly with ESP-12E to read its contents using SPI by doing something like this. Since ESP8266 operates olny on 3.3v, I need SD card to work on this voltage.

I've used two separate SD card shields without any luck! Photos of the two shields and micro-SD card are attached.

SDHC card shield-front

microSD card shield-front

microSD card shield-back

microSD card and adapter

  • Are we supposed to guess what your circuit is doing? The only info you provided was a few pictures of the readers. What are the wires connected to? Are you saying you connected 3.3V to the "3V3" pin and left the "5V" pin open?
    – Bort
    Sep 20 '16 at 19:43
  • How do you know it's the card reader and not your code that is at fault?
    – Majenko
    Sep 20 '16 at 19:51
  • The circuitry is actually a pretty straight-forward SPI (MOSI-MOSI, MISO-MISO, SCK-SCK, CS-chipSelectPIN, GND-GND, VCC-VCC). Yes, I connected 3.3V to the 3V3 pin and left the 5V pin open. Sep 20 '16 at 19:53
  • 1
    It's probably the fault of shield because it works when I supply 5V to it. Sep 20 '16 at 19:54
  • @AshishRanjan "VCC-VCC"? That's not helpful either. What is the other VCC? Realize that it's important to document what is going on. You're asking for help, it's best to give us as much info as possible.
    – Bort
    Sep 20 '16 at 19:58

I could not find any info on the full size SD card adaptor, but the microSD adaptor has a 3.3V (LM1117 or equivalent) regulator on it. It, therefore, needs a minimum of 4.5V to operate.

To run the adaptor from 3.3V, you would have to remove the regulator and solder in a piece of wire in its place.

  • Perhaps you are right, I'll try to run it by soldering a 3.3V wire to the output of AMS1117 tomorrow. Sep 20 '16 at 20:18
  • No need to remove the ams1117. Just adding a jumper wire between in an out will suffice.
    – Gerben
    Sep 21 '16 at 7:07

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