Use external micro-SD card vs. the built-in one on the ESP32 Wrover Kit V3

[i_am_mrp]

I want to use an external micro-SD card vs. the built-in one on the ESP32 Wrover Kit V3 board.

It seemed that older (pre V3) boards had pins (SD_IO2, IO2) that needed to be jumped so that the uSD card would be enabled. In the V3 board version, those pins are gone, and it seems the uSD card is enabled by default. I was able to use the IDF sample code and my own code to access the on-board card so I know that works.

I need to test an external micro-SD card HW (the one that will be in my production product). How do I disable the on-board card so I can use an off-board one?

[WiFive]

Take it out of the slot?

[i_am_mrp]

In any case, physically removing the SD card (media itself) and using it elsewhere is not the issue.

Perhaps my question needs to be clarified?

The question is: Do I need to disable the on-board SD card reader circuitry before I use the same GPIO to attach to an external SD card reader?

I looked at the SD card schematic and seems adding essentially another SD card reader to the same GPIO would not work. Doing this would mean the same GPIO are connected to 2 physical SD card readers at the same time.

My understanding is both (or more) SD card readers could share the same lines for {MOSI, MISO, CLK} but need separate lines for the slave/chip select (SS or CS) where only one select line can be low (active low scenario) at a time.

If the V3 board had a jumper to disable the on-board SD card reader, then I could "just reuse" the existing GPIO as is.

Thank you.

[WiFive]

It is just a connector, so if there is no card, the gpio are not really connected to anything. Are you trying to use 2 cards at the same time in SPI mode?

[i_am_mrp]

I want to use/test a single SD card reader (the one I will use in a production system) vs. the on-board one.

There is physical circuitry connected to the on-board card reader with various pull-ups (10K 1%) and voltage-suppressor diodes on the lines.

I am still pretty new to electronics design and the ESP32 so I wasn't sure if just not having the physical card media inserted would be sufficient so I could just wire up my external SD card reader and not have any problems. Based on your comment I won't.

I was using 4.7-6.2K pull-ups on my other circuits for the SD cards; I don't think the 10K will be much of an issue but will relook at the specs and then try it out.

Thank you.