MicroPython Forum (Archive)

Hi community.
After connecting pyboard to my PC, I insert MicroSD Card to pyboard. Just standard boot from flash.. When I write
>>> os.listdir('/')
I can see
['flash', 'sd']
so, it's clear that the board can identify SD Card. But when I write
>>> os.listdir('/sd')
I get this error;
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
OSError: No such file or directory: '/sd'

So, I can't read or write SD card. What could be the problem?

I think that only unpatrtitioned SDcards which are formatted using FAT32 are supported.

I know lots of SDs get reformatted using multiple partitions (for say Raspberry Pi), and I don't think that these are suppoted.

Thank you for your answer Dave. Bad luck for me because I have tried 2 different SD card which are formatted single partition FAT32 I changed one of them to NTFS, it's same. Now I'm trying EXT4.. No, it's same. What can I do anymore?

You have to carefully read Daves answer

Unpartitioned SD card. Means no partition at all.
Under linux that means you need to have no sdb1 or sdbX but only sdb.
And you need to format sdb and not sdbX

Not sure how to manage this under the windows world, which I left long time ago.
There is no support for EXT4, NTFS and Co.
Good luck

EDIT: Could be also sdc sdd or whatever, you need to check... don't tell me you erased your harddisk by using my sdb example

Hi folks, I cannot confirm that. I just looked at two SD cards on two systems, size 8 and 16GB, but I had a 64GB card used too. Boths cards are accepted by PyBoardV1. Both have a single partition with a partition sector formatted as FAT. On on system, the cards show up as /dev/sde1, on the other as /dev/mmcblk0 and /dev/mmcblk0p1. What I did, I reformatted the cards before using as FAT.
SO maybe you should confirm that the cards have a single partition only, or use a different computer for verification, that they are properly formatted.
P.S.: When inserted into PYBoard, the cards are shown as /dev/sdc1.

I used GParted to format SD Cards, under Linux. No flags, no partitioning, just plain format to FAT32.
Note that; there is NO trouble when I reset the board while SD card is connected. PyBoard is running from SD Card properly. So, I don't think there is a format unsuitability.

Now, I'm going to change the firmware to the latest version.

Hello ahmet_cihan, just two questions:
a) are there any files on the SD card you're trying
b) when PyBoard is connected to your PC, is the SD card visiblle as external drive?
Regards, Robert

Hi Robert.
1- There is not any file on the SD Card.
2 - When I boot Pyboard with a SD Card, PC can see SD Card as an external drive. In this case there is no problem. Problem occurs when I connect SD Card after flash boot.

I changed the firmware to the latest. What now; I insert SD Card after flash boot
>>> os.listdir('/')
I can see
['flash']

This is more logical Because formerly, I could see 'sd' with this command but it gave error when I tried to list 'sd'. But now I can't see 'sd' in the list of '/'.
Still no problem with SD boot.

What do you mean with

Still no problem with SD boot.

, especially when there is no file on the SD card.
PyBoard boots from its image in flash outside the file system. It just takes boot.py and main.py from a filesystem in flash or SD if present.
There might be a problem with the SD card connector.

I will explain step-by-step;

SD Card: no data, no file, FAT32 formatted.
PC: Linux (Ubuntu 15.04)

A - Connect SD Card -> then -> Plug in USB
1- Command "screen /dev/ttyACM0"
2- Darkness
3- CTRL+C
4- I have console.
5- >>> import os
>>> os.listdir('/')
['flash', 'sd']
6- No problema!

B- Plug in USB, NO SD Card
1- Command "screen /dev/ttyACM0"
2- Darkness
3- CTRL+C
4- I have console.
5- >>> import os
>>> os.listdir('/')
['flash']
6- Connect SD Card
7->>> os.listdir('/')
['flash']
still cannot see 'sd'