Issue with SD card

[odavlias]

Hello,

I'm using the ESP32 devkit which is mounted in a custom PCB I've designed. I'm developing using micropython and have an issue when trying to connect an SD card.

The setup is as follows:

An micro sd card adapter (not module) is connected to the appropriate sdmmc pins (slot 1 in 1-bit mode: sck: pin 14, cmd: pin 15, d0: pin 2). All three pins have external pull up resistors (10k) and I've put a decoupling 100nF between the SD 3.3 and ground.

When trying to execute the following:

import machine
import os

sd = machine.SDCard(slot=1, width=1)
os.mount(sd, "/sd")

I get: E (71080) sdmmc_sd: sdmmc_init_sd_scr: send_scr (1) returned 0x109

When I add the following line in the code (before the sd=... statement):

machine.Pin(2).init(-1, machine.Pin.PULL_UP)

I get: E (83920) sdmmc_sd: sdmmc_init_sd_scr: send_scr (1) returned 0x107

Does anyone have any suggestions?