SD MMC peripheral on ESP32-S3

[Nico-GYW]

Hi everyone,

I have recently discovered the esp32 and Micropython environment and am stuck using the built-in SD/MMC hardware peripheral on an ESP32-s3.

My home made development card has the following hardware connections:

ESP32-S3 pin	SD card pin
GPIO36	CLK
GPIO35	CMD
GPIO37	D0
GPIO38	D1
GPIO33	D2
GPIO34	D3

I took these hardware connections from an ESP32-S3 development board. Here is a link to the repo of the example of the use of the SDMMC card of espressif. Note that : "On ESP32-S3, SDMMC peripheral is connected to GPIO pins using GPIO matrix. This allows arbitrary GPIOs to be used to connect an SD card."

When I read the Micropython SDCard class library for esp32, access to SD or MMC storage cards using dedicated SD/MMC interface hardware is done by specifying slot 0 or 1. Since slot 0 is used to communicate with on-board flash memory on most ESP32, I use slot 1.

The library specify that the pins used by the dedicated SD/MMC hardware are fixed and as follows :

Slot	0	1
sck	6	14
cmd	11	15
cs
miso
mosi
D0	7	2
D1	8	4
D2	9	12
D3	10	13
D4	16
D5	17
D6	5
D7	18

Could you advise me if it is still possible to use my SD card with my hardware configuration. If yes how, by adapting the machine_sdcard.c file of the library ?

Thank you in advance!

[jimmo]

Could you advise me if it is still possible to use my SD card with my hardware configuration. If yes how, by adapting the machine_sdcard.c file of the library ?

You will need to configure the pins in machine_sdcard.c according to these instructions:

https://docs.espressif.com/projects/esp-idf/en/v4.4.2/esp32s3/api-reference/peripherals/sdmmc_host.html#configuring-gpios

The corresponding place in machine_sdcard.c is here https://github.com/micropython/micropython/blob/master/ports/esp32/machine_sdcard.c#L248

[cyril1116]

Hi @dotnfc, here is output:

import machine
sd = machine.SDCard(slot=1, cd=None, wp=None)
sd.info()

Making new SDCard:n
  Unpacking arguments
  slot=1, width=1, cd=6, wp=6
  miso=6, mosi=6, sck=6, cs=6
  Setting up host configuration
  Calling host.init()
  Setting up SDMMC slot configuration
my sdmmc used
  Calling init_slot()
  Returning new card object: 3c1630c0
  Calling card init
  Card init returned: i
Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
OSError: (-264, 'ESP_ERR_INVALID_RESPONSE')

import machine, os
sd = machine.SDCard(slot=1, cd=None, wp=None)
#sd.info()
os.mount(sd, "/sd")

Making new SDCard:n
  Unpacking arguments
  slot=1, width=1, cd=6, wp=6
  miso=6, mosi=6, sck=6, cs=6
  Setting up host configuration
  Calling host.init()
  Setting up SDMMC slot configuration
my sdmmc used
  Calling init_slot()
  Returning new card object: 3c163130
  Calling card init
  Card init returned: i
Traceback (most recent call last):
  File "<stdin>", line 4, in <module>
OSError: 16

Why is "i" printed in "Card init returned" ? But it is definetly not ESP_OK...

[dotnfc]

• for the 'Card init returned: i', you may change '%i' to '%d'
  DEBUG_printf(" Card init returned: %i", err);
  -->
  DEBUG_printf(" Card init returned: %d", err);
• for the 'OSError: (-264, 'ESP_ERR_INVALID_RESPONSE')', can you use the same card in Arduino SD_MMC env?
  ESP_ERR_INVALID_RESPONSE: if the card does not (correctly) support CIS.

and here is my machine_sdcard.c output for a 16GB tf card.

MPY: soft reboot
Making new SDCard:n
  Unpacking arguments
  slot=1, width=1, cd=6, wp=6
  miso=6, mosi=6, sck=6, cs=6
  Setting up host configuration
  Calling host.init()
  Setting up SDMMC slot configuration
  my sdmmc configuration
  Calling init_slot()
  Returning new card object: 3fcb2930
  Calling card init
  Card init returned: 0

>>> sd.info()
(16047407104, 512)

[cyril1116]

Hi @dotnfc, sorry for late reply, was busy with other duties.

Here is output with %d instead of %i :

import machine, os
sd = machine.SDCard(slot=1, cd=None, wp=None)
sd.info()

Making new SDCard:n
  Unpacking arguments
  slot=1, width=1, cd=6, wp=6
  miso=6, mosi=6, sck=6, cs=6
  Setting up host configuration
  Calling host.init()
  Setting up SDMMC slot configuration
my sdmmc used
  Calling init_slot()
  Returning new card object: 3c161570
  Calling card init
  Card init returned: 263
Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
OSError: [Errno 116] ETIMEDOUT: ESP_ERR_TIMEOUT

I tried to setup this display with Arduino. I followed this tutorial from manufacturer of this board: https://github.com/Xinyuan-LilyGO/T-HMI/tree/master#arduino and then run theirs test program for SD cards: https://github.com/Xinyuan-LilyGO/T-HMI/tree/master/examples/sd and it works! It can read all my cards... 2gb, 16gb, 32gb, 128gb. Hmm so board is working, just micropython is not for some reason :( Do you have any idea please what could be wrong?

[cyril1116]

Hi @dotnfc, thanks for everything, I was able to solve this :) Your tutorial how to modify micropython was very helpful and totally worked, thank you! But what I forgot was to trigger GPIO10 on my particular board to enable 3.3V for powering SD card, more here - Xinyuan-LilyGO/T-HMI#9 (comment) and here - https://github.com/Xinyuan-LilyGO/T-HMI/blob/master/schematic/Schematic.pdf

[dotnfc]

well done! ^)^

[JeanGC970520]

How I can rebuild the firmware with this changes? @jimmo

[jimmo]

Build instructions are here: https://github.com/micropython/micropython/blob/master/ports/esp32/README.md

[JeanGC970520]

Great thank you very much

[jornamon]

I landed here trying to do the same thing. It seems inconsistent to allow users to select the SPI interface pin assignments, yet force a fixed pin assignment or require a rebuild process for the SD/MMC interface.

While @dotnfc’s solution is better than hardcoding the pins in machine_sdcard.c, why not allow users to pass the arguments for SD/MMC pins the same way as for SPI?

This would make it easier to use the SD/MMC host in the ESP32-S3 (and possibly ESP32-S2?), which can offer speed improvements with a larger data width. This could be beneficial for heavy data logging applications. Additionally, it would dedicate the specific SDIO interface for the SD card, freeing up the more general-purpose SPI interface for other uses.

@jimmo, would this be a nice improvement, or am I missing some downside?

[JohannesMaierhofer]

I would also appreciate an update to allow the user to pass the arguments for SD/MMC pins for the ESP32S3.