SD_MMC incompatible with Feather Music Maker?

[MontreuilMonsieur]

Hello there,

The goal
My goal is to increase the writing speed on the SD card OTA to upload huge WAV files, and while the SD library works, the speed is kindof mediocre with around 50kb/s using a modified version of https://github.com/G6EJD/ESP32-8266-FIle-Upload + a custom buffer. The reason i'm trying use SD_MMC library is that it's potentially much faster than the SD library:
https://www.youtube.com/watch?v=e1xOgZsnAuw
https://www.reddit.com/r/esp32/comments ... alk_to_an/

The specific problem:
While using an Esp32 HUZZAH Feather board connected to a Featherwing Music maker, it would seem the SD_MMC cannot function properly?

Here, SD.MM.begin() always fails.

Code: [Select all] [Expand/Collapse]

1.  
2. if (SD_MMC.begin())
3.   {
4.     Serial.println("WOW!");
5.     return true;
6.   }

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The error message I get is this one:

Code: [Select all] [Expand/Collapse]

1. 12:20:00.969 > E (1057) sdmmc_common: sdmmc_init_ocr: send_op_cond (1) returned 0x107
2. 12:20:00.969 > [E][SD_MMC.cpp:85] begin(): Failed to initialize the card (263). Make sure SD card lines have pull-up resistors in place.

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I have also tried changing some pins INPUT_PULLUP,'s and play with the functions parameters for 1-4 bit mode, but without success.

Code: [Select all] [Expand/Collapse]

1.   pinMode(13, INPUT_PULLUP);
2.   pinMode(15, INPUT_PULLUP);
3.   pinMode(2, INPUT_PULLUP);  
4.   pinMode(14, INPUT_PULLUP);
5.  
6.   if (SD_MMC.begin("/sd", true))
7.   {
8.     Serial.println("WOW!");
9.     return true;
10.   }

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Platformio config:
[env:esp32]
platform = espressif32
board = featheresp32
framework = arduino