Push-Pull uSD Card Socket

JonnyMac

I'm looking for a push-pull socket for a Propeller project -- was hoping to get a recommendation by those who may have already deployed them. My client wanted the flip-up type, but quickly found he could break them without an effort on his part.

Second... I may have on too many pull-ups on my interface. If my [sometimes wacky] memory serves me there is no for a pull-up on the CD line (?), and that line can be pinged to see if a physical card is presents.

Thanks for any suggestions or guidance.

JonnyMac

(Why can't I add an image to a previous post?)

This is the current uSD interface -- have used with with FSRW in many projects. It works fine. If I can drop a resistor and do card detection without attempting to mount the card, that would be great.

Publison

JonnyMac wrote: »

(Why can't I add an image to a previous post?)

Forum software is wonky. I have added an image to a second post, copied the url to the first post, then deleted the second post, and the image disappears on the first post.

Oh well. It is what it is.

Tracy Allen

Hi Jon, SD and µSD cards have an internal pull-up on the chip select (CS\) line. Test it for high to detect card present/not present. (pull low, release to input, test). If the socket has a CD (Chip Detect) pin that is a different thing, you know, just a mechanical switch that connects to ground when the card is inserted.

To help with proliferation of pullups, I usually tie together DAT1 and DAT2 to a single pullup. Also, I usually skip the pullups on the other pins as well and make the Prop side low outputs if the card is not present.

I've used the push-push socket, Hirose ZX62-B-5PA(33), but lately went back to full size cards for a variety of reasons, not the least of which is the annoying ease of losing the cards.

Cluso99

These are PUSH-PULL...

I use the HR1941CT from Digikey. The solder pins are easily accessible on the front for inspection/hand-soldering/etc. Fairly small footprint.
I now also use the 538-105162-0001 from Mouser on my P8XBlade2.

I only use a 10K pullup on -CS although Peter Jakacki has noted elsewhere, this is not required either.

PropGuy2

Yes - I use the same HR1941CT-ND from DigiKey. It is the exact same one used on the Prop Project board and other Prop products (accessories items). Parallax has numerous schematics for SD card circuits, all work great. Easy to use & solder, and it lasts a long time.

Don M

I have been using these Hirose sockets. DM3AT-SF-PEJM5 They are push-push which I prefer.

Peter Jakacki

I think I've used just about every type, all have their advantages and disadvantages, just depends upon the application. I know those header style ones are very neat for my IoT modules but I don't think I will have the next lot extending the fragile microSD out past the board right under where the cat5 plugs in !!!

I have used the MOLEX 49225-0821 (which now seems to be obsolete, sorry) in a design and I even have a Protel footprint for it too. I find it totally unnecessary to have any pull-ups on microSD and especially the CS line as that is the soft (and recommended) card-detect line as has been mentioned. By all means have a decoupling cap right next to the card but also allow for bulk decoupling somewhere close for some cards, even a 4.7uf ceramic is fine.