SD card interface

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jremote

New Member
I am a new user and will help in this forum as much as possible.

My project:

I have a SD(secure digital) card that I R/W with Pic16f877A. The SD card operates on 3.3 v but I need the Pic to run at 5v. I need an IC that I can interface to the SD card for 3.3V data. (resistors are not acceptable).

Anyone ?
 

Why aren't resistors acceptable?.
 
Res

They will work but I like to keep my design as accurate as possible. there is a small margin of error with load resistors. I would rather get the digital 3.3 volts. I think maxum makes a chip but I fail to find one. The SD card I am useing has specs that allow 5v operation but some on the market require Max 3.3v I dont have control on the end user's choice of cards.

Thanks for your replay.

Jerry
 
res

I have decided to proceed with Res. I calc a 100 omh / 150 ohm to get me within 3v tolerance. The DO should still trigger the Pic at 3.3 v ? Does anyone have a good schematic ?
 
Re: res

jremote said:
I have decided to proceed with Res. I calc a 100 omh / 150 ohm to get me within 3v tolerance. The DO should still trigger the Pic at 3.3 v ? Does anyone have a good schematic ?
Click to expand...

From the 3.3V to the PIC requires nothing, a PIC will quite happily accept 3.3V logic levels to it's inputs. From the PIC to the 3.3V simply requires a potential divider, consisting of two resistors in the ratio 50/33, there's not really any schematic required?.
 
card

I am stumped I cannot get the code to work.

I set up the SPI , Initialize card with 80 clock ticks and followed the advice of the pros. I think I will try AT45DB041 chip.
 
I know this is an old post, but for anybody who happens to have the same question: You need to use a voltage translator such as MAX3002 or ADG3308. You should be able to get that from mouser or digikey.

Melissa
 
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