SD card pinout

Designing hardware that use VLSI Solution's devices as the system controller for the entire design.
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scf
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Posts: 5
Joined: Tue 2021-07-06 21:55

SD card pinout

Post by scf »

On some of your designs with the VS1010, you've used a standard microSD card connector. That's fine.
SD card 1.png
SD card 1.png (47.18 KiB) Viewed 907 times



On other VS1010 designs, you've used a connector with two CD pins, one of which is used to control the 3.3V supply to the SD card and is also connected to GP0_8 on the VS1010.
SD Card 2.png
SD Card 2.png (74.4 KiB) Viewed 907 times


The data sheet for that connector (Tomin MSSN09-A0-3000) seems to be unavailable, or at least very very obscure.

Would you please explain what you're doing in this second case? Are you enabling the 3.3V regulator with GP0_8, and then disabling it under some circumstances? Since SD cards have only one CD pin, and it's shared with DAT3, how does that enable work?

Thanks!
Hannu
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Joined: Mon 2016-05-30 11:54

Re: SD card pinout

Post by Hannu »

card detect 1 and card detect 2 are open if there isn't card inserted. when card is inserted CD1 and CD2 are connected.

As the CD2 is connected to GPIO pin it is possible to do two things. First is card detection and the second is power cycling the SD card.
card detec pins 11 and  12
card detec pins 11 and 12
minidemo_sd.png (3.77 KiB) Viewed 903 times
Here's how the connection looks on the connector side.

The connector has been updated without footprint/symbol change and it is really old. One compatible connector is https://www.digikey.com/en/products/det ... 51/3044809
scf
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Re: SD card pinout

Post by scf »

Thanks for the prompt reply.

What is the need to power cycle the 3.3V rail to the SD card slot? Is that required by the SD spec? I can understand that in designs with a user-removable SD card, it would be useful to software to be able to detect the absence of a card.

Thanks!
Hannu
Senior User
Posts: 361
Joined: Mon 2016-05-30 11:54

Re: SD card pinout

Post by Hannu »

Sometimes SD-card get's stuck. Usually this is some kind of brown-out situation or VSDSP thinks card being in some other state than it is.

I usually experience this when programming VS1005 Breakout board Mk2 and first boot to installed system requires cold boot. So far I haven't seen any other repeatable problems.

Another aspect is power down. When the power is shut off, SD card may take some mA power and before shutting down the IOVDD regulator, driving the SD regulator down and then powering off can be difference between power down and brown out state.
scf
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Re: SD card pinout

Post by scf »

That all makes sense. Thanks for clarifying.

Since the project is very cost-constrained, the cheaper connector without the extra card detect might be better for us. I can still use a GPIO to control the regulator enable, so that the power can be suspended as needed by software.
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pasi
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Re: SD card pinout

Post by pasi »

If you compare to the vs1000 audio module schematics, that one uses a single CardDetect, and a different GPIO pin to control the 3V3 regulator.
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