SD Media Controller  - Page 1
Forum section: electronics / beginners

author: adamjy12345
author_rank: Newbie
timestamp: November 06, 2015, 12:04:48 am
content: Hello all,I'm new to the forums and first time poster. I'm getting into electronics and having fun playing around on some projects. I'm currently working on a project creating a SD card reader through USB. I know that you can purchase one but I want to make a duel SD card reader. I've looked online for the last two weeks and found some interesting information. I'm unable to find anyone that has already created one (besides a few on Amazon, eBay: commercially). But I want to create my own.I think my biggest hurdle is finding the correct Host controller (as I can find plenty of schematics on a singe SD card reader). I found Multi Host controllers that do all the different types but can I repurpose them to do just two SD Cards?Maybe its not possible without manufacturing a host controller. But I can't find the answer anywhere else and I'm hoping that I can end my. I apologize in advance if my terminology is incorrect, I'm learning something new every day. Though not new to electronics but creating them i am.Cheers,Adam

author: rs20
author_rank: Super Contributor
timestamp: November 06, 2015, 12:17:32 am
content: Many options here,A) Find a controller than can do two SD cards (apparently you're having trouble with this)B) Use two separate single-SD-card controllers and put a USB hub chip on the same board, thus giving you a device with a single USB plug but appears as two separate SD card readers (which presumably suits your purpose just fine)C) Use a microcontroller with a USB interface and write your own code.

author: max666
author_rank: Frequent Contributor
timestamp: November 06, 2015, 05:46:01 am
content: If you really want to create your own, then I can't help you, don't know anything about that.But since you asked if one could repurpose multi host controllers, I would think yes you can. For example I have the "Kingston MobileLite G4 Reader, USB 3.0 (FCR-MLG4) € 9,13" which has a SD and a microSD slot and it can access both slots simultaneously. It's a very good card reader. And since I believe pin-out between SD and a microSD is identical and adapters are solely passive, it would be easy from there.Even more simple I guess would be to get "InLine OTG Cardreader Dual Flex with Hub, USB 3.0 (66774) € 11,99" and be done.But I have a feeling I'm answering something you didn't ask.

author: adamjy12345
author_rank: Newbie
timestamp: November 06, 2015, 04:51:32 pm
content: Thank you both rs20 and max666. You have given me a good ideas. I'll take a look at the chip that you mentioned and see what I can come up with.Cheers,Adam

author: M.Stallnig
author_rank: Newbie
timestamp: November 12, 2015, 01:03:36 pm
content: Hello.I want to build a sd card reader as well, but for only a single card, preferably with usb3.You wrote you know where to find schematics for single sd card readers, could you tell me where? (I haven't found anything in 2 weeks of search, and I don't think I can reverse engineer one)Since I am absolutely new to electronics and don't know what I need to know to get through this project, do you have some tips for me what and where to investigate?

author: max666
author_rank: Frequent Contributor
timestamp: November 12, 2015, 02:49:11 pm
content: Why? Why? WHY?!"I am absolutely new to electronics" and "build a sd card reader, preferably with usb3" does not compute.If you need an sd card reader, then buy one.If you want to learn about electronics, pick an easier project. If the goal for whatever reason is sd usb3 card reader, then I guess start learning about microcontrollers. Learn how to access an sd card with a microcontroller. Then maybe step up your game with bigger microcontrolers with usb interface, maybe go to FPGA's. But again, this would be a long way to go and not a beginner project.

author: M.Stallnig
author_rank: Newbie
timestamp: November 13, 2015, 02:27:33 pm
content: I knew it would be tough to begin with something as crazy as this, but I am known for going all out crazy with my projects.I may be not quite a beginner though:I am a 25 years old metal-designengineer. I have basic knowledge about electric principles and a bit about how cirquits work.I can assemble my own PC, and know about its parts. I am savy on Windows, down to the registry, have basic understanding of c++, c#, flash actionscript, and VBS.I haven't soldered anything yet, but that will be the simplest part to learn. I have already looked into electronics and SMD as far as I could on my own.Also I played lots of Minecraft (Redstone and stuff).Since you asked why I want to do this:I initially didn't plan on building a cardreader my self, but only a prop of this memoryunit from the game "Halo":http://s1201.photobucket.com/user/JustinBranfuhr/media/Cortana/Cortana5_zps76c054fb.jpg.htmlIt would feature some LED, powered by a micro-USB port. (I can figure out the math behind that)After dismantling a cheap USB2.0 memory stick, it turned out to be only a micro sd-card with a same size PCB. This thing is tiny!I thought I could integrate this to actually make my prop a working memory stick.The thing is, I want to make the prop original in size and it turned out, that the main body is going to be only 3mm thick. I stick to that, otherwise I could have been done already.So, I plan on making it out of 3 stacked sheets of 1mm-PCB, which allows for 1mm space in between the outer 2 sheets.The LED-part is still doable, but even though the PCB from the memory stick is tiny, it's too thick to fit in between there. It is made up of a 1mm pinrow for the sd-card, a 0.8mm PCB,and a layer of around 0.4mm smd parts (and a COB-Blob of 1.5mm, which is yet another, but probably solvable problem). Also the sd-card itself is 1mm thick.Then I found this USB 3 micro sd-card reader with high capacity sd-card:http://shop.graphicart.ch/images/product_images/info_images/128gb_microsdxc_633x_w_3.0reader.jpgI bet it features a pcb close in size to the one I have present. If possible, why not go straight for that...And this is as far as I got. If I knew the cirquit, I could recreate it in a more distributed way directly on my own 3 PCB-sheets, but I can't find any schematics,and I'm surely not able to reverse engineer such a tiny device on my own. And so I came here, to ask if anyone does already have access to schematics,or would be smart and kind enough to pull some off the cuff.Actually designing and programming my own card reader would surely be insane at this point, but if there's no way around, maybe someone could at least tell me what I would need to know,and where to look that stuff up, to actually go the hard way and build up from scratch.I'm glad for every input.

author: M.Stallnig
author_rank: Newbie
timestamp: December 09, 2015, 03:53:43 pm
content: For those interested, I made a seperate post for my project:https://www.eevblog.com/forum/projects/cortana-chip-microsd-card-reader/msg817450/#msg817450

author: amyk
author_rank: Super Contributor
timestamp: December 10, 2015, 10:43:27 am
content: It's not that hard, others have done it... but be prepared to read a lot. At the minimum, you'll need to read- USB spec-- USB mass storage spec--- SCSI passthrough command set- SD spec- datasheet for MCU you want to useI actually happen to have read all those, and I'd say making one would take a few weeks at least. It won't be very fast, but it will work, and you'll probably learn a lot in the process.Here is an example:https://davidgf.net/page/20/pic-usb-sd-card-reader