Quick SD Pullup question...

[AtomSoft]

Do i really need pull-up resistors? If so where?

 

[be80be]

If you want it to work you do LOL I can't say I've seen it both ways but it's in there data sheet **broken link removed**



**broken link removed**

 

[AtomSoft]

i forgot to not im not using a 5v pic im using a 3.3v system (ARM and PIC) .

Also in your schematic the only pin pulled high is CS. So ill assume that has to be pulled high. Also shouldnt it be before the 470 ohm resistor and not after?

NOTE: All are pulled low technically.... if its high the voltage is divided if not its low as normal...

 

[be80be]

I don't no for sure the frist is for 5 volts

and this is for 3.3 **broken link removed**

 

[be80be]

This should tell you all you need to know https://www.electro-tech-online.com/custompdfs/2010/10/ProdManualSDCardv19.pdf

I played with a old card and hooked it up wrong so i put is on the back burner

NOTES: 1) S=power supply; I=input; O=output using push-pull drivers.
2) The extended DAT lines (DAT1-DAT3) are input on power up. They start to operate as DAT lines after the
SET_BUS_WIDTH command. It is the responsibility of the host designer to connect external pullup resistors to all
data lines even if only DAT0 is to be used. Otherwise, non-expected high current consumption may occur due to the
floating inputs of DAT1 & DAT2 (in case they are not used).
3) After power up, this line is input with 50Kohm(+/-20Kohm) pull-up (can be used for card detection or SPI mode
selection). The pull-up may be disconnected by the user, during regular data transfer, with
SET_CLR_CARD_DETECT (ACMD42) command

 

[Noggin]

It might not be useful, but I've done several projects using a PIC32 and a uSD card. I put a 750k pull down on the chip select line because the uSD card has a weak pull up built into it. When you insert the card, the chip select line will go high and I use that to detect a card insertion. Much simpler and cleaner than constantly trying to write data out to the card and seeing what comes back.

 

[AtomSoft]

Thanks guys! To make life simple ill add 20K pullups to all PINS (NON POWER PINS):

 

[AtomSoft]

hey guys take a look at the sd breakout here:
LPC2103 Expansion w/ Power board & SD Breakout w/ Pull Ups « Atomsoft's Blog

 

[DirtyLude]

You only need to pullup lines that could be left floating. Many people don't use any pullups at all and there's no issue. Spec shows pullups on CMD and DAT0 thru DAT3 pins. I would pullup pins 8 and 9 if you are using SPI Mode.

All I use is MicroSD now, because I like the size. SD seems huge to me now, especially how much space it takes up on a layout.

EDIT:Looking at the picture, it is MicroSD.

 

[AtomSoft]

yeah Im using microSD heh i love the size!!! space saver on PCB heh... I just took some new pictures. I had to repair the Card detect trace. SO i tested it in these pics and it works great!

Image of MicroSD NOT pushed in :
**broken link removed**

Image of MicroSD pushed in :
**broken link removed**

This is a Push-Push MicroSD Connector... meaning you push it in and it locks then you push it in again and it pops out .. spring loaded heh

EDIT:

I heard pulling up the RSV pins DAT1 and DAT2 i think they are? 1 & 8? reduces power consumption also.