Running main.py from SD card on OpenMV Cam H7 Plus?

OpenMV Boards
1

Hi, I’m trying to run main.py from an external SD card on a LiPo powered OpenMV Cam H7 Plus.

From the docs and forum posts it seems that if an SD card is present, containing a file named main.py, the bootloader should run it, however that does not seem to work on my cam.

Here’s what I tried, on MacOS Monterey:

  1. Updated OpenMV IDE today and flashed newest firmware when the IDE prompted me.
  2. Erased the internal flash with OpenMV IDE > Tools > Erase Onboard Data Flash.
  3. Manually deleted the content of the NO NAME drive that shows up when the cam is connected.
  4. Formatted the external SD card with ExFAT (also MS DOS FAT before), named it OPENMV.
  5. Saved your blink example in a file called main.py to the SD card.
  6. Ejected the OPENMV SD card from MacOS.
  7. Inserted the OPENMV SD card to OpenMV cam.
  8. Powered the OpenMV cam (first with USB and later with just a fully charged LiPo battery).
  9. No blinking (!) which probably means the code does not run.

(If I “Save open Script to OpenMV Cam” the exact same code runs as expected, but from flash.)

Did the default bootloader change, or do I miss a file (e.g. boot.py, and if yes, how should it look)?

Kind regards,
Thomas

2

Hi, after saving the file did you safety remove the hard drive?

Generally, the issue would be because the script either has an error or it was not written.

This should not be complex.

3

The script should be called main.py.

4

Thanks for the quick reply.

Yes, the file is called main.py and I did eject the SD card via MacOS.

5

The content of the script is the same as

OpenMV IDE > File > Examples > OpenMV > Basics > main.py

6

Might want to try reformatting the SD with exFAT, or trying a different card.

7

Tried ExFAT and MS-DOS FAT.

Also tried to read the (same) card on a Linux machine, works fine.

Will try to find another card.

8

Some cards just don’t work with ST SDIO core and/or drivers. I know for sure that Samsung EVO works very well with the cam, but you could try any other card. main.py should run from any available storage (flash or sd).

1 Like
9

You were right, using a different SD card seems to solve the issue. Thanks a lot.

10

OK, after further investigation I guess it was my sloppy formatting that caused the issue. MacOS Diskutil shows two entries for a single SD card. Seems to be important to select the “Generic STORAGE DEVICE Media” one (not its child entry) and select “Master Boot Record” in addition to “ExFAT”. Anyway, now both (Kingston 16 GB) cards work fine with the cam.

11

I have the same issue and I also tried replicating these steps with no luck. I’m using a SanDisk 32GB card. I formatted it to ExFat with a MBR scheme. The weird part is that it was working fine before, then suddenly stopped working, and that’s when I found this thread and tried the steps with no luck.

12

Hey, sorry for resurrecting this thread.

The marked solution doesnt work for me. I have a new H7 plus cam and tried 4 different SD cards. I also tried different formating programs on windows (the standart one, rufus, the one from sdcard. org mentioned here). I also tried different formats (exFAT and FAT32) and even got a mac and tried with the exact same settings as shown in the screenshot above.
One of the SD cards I tried is a new Samsung Evo Select (2024) 128GB - I saw that people recomended that model, for example in this thread.
Firmware on the cam is 4.7.0 - the most current one as of today.

What I do after formatting:

  • Put a “main.py” file with some basic content onto the root of the SD card
  • Put the SD card into the camera
  • Plug the camera with USB into the computer

What I expect:

  • To see the SD card file system in the windows file explorer (128 GB)
  • An openmv_disk file be created on the SD card

What actually happens:

  • The cam blinks a couple of times rapidly green
  • Blinking stops
  • The internal flash is mounted (111KB free space)

Is there anything I am missing? Anything I need to do, forgot or am doing wrong?
Any suggestions what I can try? Is there a chance the cam module is defect?

Any help appriciated.

13

Hi, I’m not exactly sure what the error is. I can confirm that the latest firmware, v4.7.0 works with the H7 Plus and an SD card. An 128GB PNY card shows up just fine. Is it possible the uSD card slot on your camera is damaged?

14

Appriciate the swift response!

In theory of course possible - however the cam is brand new and shows no visible damage on the slot. It only arrived a couple of days ago and is the first openmv product I purchased, thats why I suspected me doing something wrong.

Anything else to try except ordering a second one?

15

Update - good news and bad news: a new module fixed it.

16

A new camera board? I haven’t heard of the SD card slot being damaged. This is a new type of failure.