Parallax SD products

idbruce

Here is the scenario.....

If I visit this link: https://www.parallax.com/product/32313 and scroll to the bottom of the page, there is the pic shown below, with no active link. Upon further investigation, I arrive at this page: https://www.parallax.com/product/32312, which states the product is not available. Then if I go to documentation for that product, I end up with a PDF that has a schematic for this product. Now I am wondering if Parallax had a problem with this product and if the schematic is a good working design, and if so, what would be the value for the various resistors?

Mike Green

Parallax has been building this into their products now with the Activity Board, Board of Education, QuickStart Human Interface Board, Memory Board, etc. all having SD cards. The Project Board has the pads and traces for an SD card option. This adapter is really for older projects or breadboard-based projects where this form-factor is useful. I've used 10K resistors for the pullups. I'm sure anything from around 3.3K to over 20K would likely work with the usual tradeoffs of power consumption vs noise tolerance and lead length.

Genetix

Mike, the development boards use MicroSD, which are smaller than SD.

Bruce, parts of the Parallax website aren't up to date.
Is this what you were looking for?
https://www.parallax.com/product/452-10017

Mike Green

Genetix ... Sorry, I was being lazy leaving out the "Micro"

idbruce

Thanks Mike, I appreciate your detailed answer. I don't see you posting much lately. I certainly hope all is well with you.

@Genetix

I actually have a couple microSD holders on hand, but I really wish I had one of those adapters shown in Post #1.

idbruce

If anyone has a micro-SD Card Adapter (Product ID: 32312) that they do not need, I will happily swap them an SD Card Adapter (Product ID: 32313) for it.

Duane Degn

Bruce,

If you can wait a few weeks, you could purchase one (or more) of these little boards from ICStation.



I'm using one with my CNC router project and it seems to work fine.

For $1.69 it seems like a good deal. I'm going to order a couple more myself.

idbruce

Thanks for the heads-up Duane

I'm using one with my CNC router project and it seems to work fine.

If I get one, is there anything that I should do special in the the wiring to get it working?

Bob Lawrence (VE1RLL)

Resistor value:

You can see the resistors in pict 2 .The resistors 103 resistors (10K ohm)

Duane Degn

idbruce wrote: »

If I get one, is there anything that I should do special in the the wiring to get it working?

I used jumper wires between the uSD card holder and the QuickStart board.

MISO on the adapter corresponds to DO in the SD object.
MOSI corresponds to DI.

I kind of wish the header pins on the adapter were pointed down rather than up but it's not a big deal and it would be easy to change.

idbruce

Thanks Duane

Mike Green

SparkFun sells a MicroSD card socket on a breakout board (https://www.sparkfun.com/products/544) but without the resistors. I've taken 1/10W 10K resistors and wrapped them around the "back end" of soldered header pins and soldered them in place on the back of the breakout board ... Soldered the other ends together ... left one of the wires long enough to bend it so it goes to the Vcc pin. Takes a few minutes to do and works great if you can't get hold of something similar with built-in resistors.

Re: Post #5. April is a busy time for me, either visiting family or attending conferences. New York was lovely on April 2nd. Thanks for noticing.

Duane Degn

Mike Green wrote: »

SparkFun sells a MicroSD card socket on a breakout board

I'm pretty sure I've used my board from SparkFun without any pull-up resistors at all. Kye mentioned many SD cards have internal pull-ups.

I'm not a fan of SparkFun's uSD board. There isn't a way to mount the board inside an enclosure while maintaining access to the SD card.

I like the $1.69 board from ICStation a lot more than the $9.95 SparkFun board.

idbruce

Mike

Re: Post #5. April is a busy time for me, either visiting family or attending conferences. New York was lovely on April 2nd. Thanks for noticing.

It is good to know that you are well and enjoying yourself, instead of going through turmoil and troubles. Last time I asked someone about their reduction in forum participation, they told me some horrible news. I sure hope their situation has improved, but I doubt it.

SparkFun sells a MicroSD card socket on a breakout board (https://www.sparkfun.com/products/544) but without the resistors. I've taken 1/10W 10K resistors and wrapped them around the "back end" of soldered header pins and soldered them in place on the back of the breakout board ... Soldered the other ends together ... left one of the wires long enough to bend it so it goes to the Vcc pin. Takes a few minutes to do and works great if you can't get hold of something similar with built-in resistors.

Thanks for the tip.... It is always nice to have various options.

Tracy Allen

SD cards have an internal pullup resistor on the CS\ chip select line only, but not on the data or clock lines. External pullups on those lines are not necessary for operation of the card. However, it can be useful to add those resistors externally so that the Prop pins will not float when the card is removed.

The fact that the card has an internal pullup on CS\ can be used to detect whether or not a card is present. Bring CS\ pin low briefly then read it a millisecond or two later. If it is high, the card is present. That won't work of course if you add an external pullup on CS\.

idbruce

Thanks for the info Tracy, that is nice to to know.