Error instantiating the SD module.

[VST Admin]

This morning I started up a sample program I was attempting to write to log serial data to an SD Card, connected to an expansion board 3. I didn't get very far before this:

# main.py -- put your code here!

from machine import UART
from machine import SD

import time
import pycom
import os

sd = SD()

Gives me the error:

Initialized watchdog for WiFi and LTE connection with timeout 1260000 ms
WiFi connection established
Pybytes connected successfully (using the built-in pybytes library)
Pybytes configuration read from /flash/pybytes_config.json
Traceback (most recent call last):
  File "main.py", line 10, in <module>
OSError: the requested operation failed
Pycom MicroPython 1.20.2.rc6 [v1.11-01f49f7] on 2020-02-28; GPy with ESP32

A version of this code was at least running without error yesterday, (even though it was not writing any data to the SD Card. This morning, I start the same code I was running and I get the above error message. That makes no sense to me.

[railmonitor]

Could there be something happening in your boot.py file that impacts the code in your main? Maybe doing the same operation?

[VST Admin]

@railmonitor Nothing changed though in my boot.py (which is empty) from one day to the next. However, I believe the internal machinations of the UART and the SD card modules are somehow stepping on each other's proverbial toes.

I have sense gotten my experiment to work again, but I have no idea why it is working now and why it gave me those messages the other day.