availability of 1.8V sd card interface with nRF52840

[sangyun Kim]

we are trying to use SD card on nRF52840 but we are facing with some issue regarding io voltage.

nRF52840 VDD voltage already are connected with 1.8V and then we can not change it. at this moment, we want to connect the sd card with nRF chip.

is it possible to connect sd CARD to the nRF chip thru 1.8V io interface?

[Jared]

Hi,

So the VDD of the nRF52840 is 1V8 and you're wondering if the SD card will work with GPIOs at 1V8? 

Well, that would depend on the SD card. What is specified in the datasheet of the SD card?

regards
Jared 

[sangyun Kim]

MicroSD PRO Endurance | Memory Card | Specs & Features | Samsung Semiconductor Global

we will use this micro sd card for this interface.  

[Jared]

Seems like 1V8 is ok for this SD card: 

[sangyun Kim]

Hi Jared.

I got the below command regarding USH-I bus mode 3.3V support is also mandatory to control SD spec.

SD memory cards have used a 3.3V signaling interface since the SD standard was introduced in 2000 and through SD Specification 3.0, when 1.8V signaling was added with the UHS-I bus mode, the ultimate removable single-ended interface. UHS-I adopted 1.8V signaling because it is suitable for faster rise/fall time and lower electromagnetic interference. However, UHS memory cards still require 3.3V signaling to initialize the card so hosts need to support 3.3V signaling, too.

[Jared]

Hi,

Ok, I don't really have that much experience with SD card. But if you supply the board with 1V8 then you can't get 3V3 on the GPIO peripheral. You would either have to use an external level shifter or increase the voltage supply.

regards

Jared