SD card wire

[livius]

hi,

i try to understand sd card connections to WIpy2.0 without expansion board

but i am confused about pinout and docs
in pinout i have
P12 MOSI
P11 MISO
P23 sdCLK
P4 sdCMD???

in docs:
https://docs.pycom.io/pycom_esp32/library/machine.SD.html
P8: DAT0, P23: SCLK and P4: CMD no external pull-up resistors are needed.
why P8?

normally i will be connect as:

MOSI - P12
MISO - P11
SCK - P23
CS to "any pin"

how to really connect this spi device?

[livius]

@livius
i reply myself ;-)
i see that i misunderstand doc - doc is about direct access to sd
by sd interface to dat0

Do i understand this now corectly? Can someone point me?
And more question in doc is:
and the current implementation only works in 1-bit mode
what limitation it create? And when it will be changed?
I am new in sd card interface.

UPDATE
I understand now 1-bit mode
there are also 4 bit mode - but 1 bit is enough for start playing

[livius]

Finally got it - this was so simple :)
here is really good overview if someone start like i with SD playing
http://www.ti.com/lit/an/slaa281b/slaa281b.pdf

[Les-A]

@livius For anyone referencing this, the link to TI has changed - just search ti.com for slaa281b and you'll find a forum entry with a link embedded in the document which contains a link to a .zip c example.

[SciWax]

@livius Sorry for pulling the thread up again. I would like to ditch the expansion board to save money and use an external SD-card module like the level shifting sd module from this supplier: https://www.sparkfun.com/products/13743

Right now, I'm using a Wipy mounted on an expansion board to connect a SD card to the WiPy. I do that, because I need to use the internal FTP of the WiPy.

Can I just wire a SD card module like in your example? Did it work in a stable manner? I had no issues so far using the expansion board v3.

I also found the following schematic for the expansion board v2. At the top, you can see how the sd module is wired on the expansion board. Mostlikely I would use that setup then:

https://github.com/wipy/wipy/blob/master/hardware/ExpansionBoard-v1.2/ExpansionBoard-v1.2_Schematics.pdf

[robert-hh]

@SciWax The schematic is for Expansion board 1.2 with WiPy 1.3. That wiring will not work with the esp32 modules. Just use the wiring as detailed in the Pinout:

P8: DAT0, P23: SCLK and P4: CMD

I have made my own carrier board using that wiring and it works fine.

[SciWax]

@robert-hh thank you, rob! I guess I don't need a sd-card module then and can directly connect the SD card to these pins like in this thread:

https://forum.pycom.io/topic/2589/wipy-with-external-microsd-card-module?_=1644102331573
https://forum.pycom.io/topic/2589/wipy-with-external-microsd-card-module/5?_=1644102135472

I guess you just soldered a card slot to your carrier board, which is directly connected to these pins on the Pycom board like suggested in the linked thread?

[robert-hh]

@SciWax said in SD card wire:

I guess you just soldered a card slot to your carrier board,

Kind of yes. I used a small carrier board avoiding the SMD soldering. The link to the board is here: https://github.com/robert-hh/Pycom-baseboard with KiCad files for PCB and schematics. The USB/Serial adapter consumes quite a bit of current (~10mA).
The board contains also the espressif logic for firmware updates. I put that board usually in a small metal box, which then serves somewhat as ground plane for a quarter wavelength antenna.

[SciWax]

@robert-hh thank you for the link, rob! I will look into it!