Copy main.py from Android assets to camera sdcard

OpenMV Products
1

Hi,

I’m trying to copy a simple script

import time
from machine import Pin
led = Pin('LED_GREEN', Pin.OUT)
while (True):
	led.on()
	time.sleep_ms(250)
	led.off()
	time.sleep_ms(250)

on a camera connected through USB to an android device.

I believe I’m successfully copying the script cat /storage/D21A-D8D4/main.py returns the copied script. Then I’m sending a reset command through serial (/dev/ttyACMX) using

val wrap = ByteBuffer.wrap(listOf(__USBDBG_CMD, __USBDBG_SYS_RESET, 0).map { it.toByte() }.toByteArray())
wrap.order(ByteOrder.LITTLE_ENDIAN)
serial?.write(wrap.array())

emulating __serial.write(struct.pack("<BBI", __USBDBG_CMD, __USBDBG_SYS_RESET, 0))

I believe the camera is properly reset… But once it’s accessible again, either main.py is empty or is back to the old script.

What am I missing?

Thanks in advance.

2

Hi, the OS will buffer writes. Please safety remove the disk.

3

Right, see I’m trying to do this in order to update the running script remotely. Is there a better way to do that?

4

I guess you could “umount /storage/D21A-D8D4”

5

Ok so unmounting the drive and then resetting the camera should do the trick?

6

Assuming resetting the device would also remount the sdcard.

7

Yes, that should flush the write. Wait a bit before sending the reset after the unmount.

8

Yep this works. Unmounting /storage/D21-D8D4 did not work as it’s not the actual mount point. umount /mnt/media_rw/D21-D8D4 did the trick.

Thanks a bunch!

9

Will the mount point always be D21-D8D4?

10

No, Linux changes this per mount.

11

Right, is there a way to reliably find the mount point?

12

Google search? If it’s a general purpose Linux question then you don’t need to ask the forums here.

13

Ah yes of course. I meant through any sort of rpc or api.

Anyway, thank you for your help.

14

Nope.

15

What I ended up doing

  1. Find OpenMV storage device root by scanning every external media for the file ‘.openmv_disk’;
  2. If this fails, parse dumpsys mount output to find Volume with fsLabel=OPENMV
  3. Unmounting said storage;
  4. Waiting a whole 5 seconds;
  5. Reset OpenMV camera with the above command.

The other tricky part for me was to ensure I was sending the command to the right serial ttyACMX. To find it I used the following grep 1209/abd1 /sys/class/tty/*/device/uevent and mapping the matching tty device to /dev/$tty.

Thanks for your help @kwagyeman.