I'm having trouble using photo-slideshow with a USB drive

The documentation is a bit confusing - photo-slideshow mentions that you can use a USB, but first directs you to the tutorial, which doesn’t mention USB’s at all.
Photo-gallery tells me that I have to set GALLERY_URL to USBDRIVE, but also says

Make sure to update CRON_SCHEDULE accordingly or else image changes will only be picked up at reboot.

But gives no guidance on what to set it to.

If I just set GALLERY_URL to USBDRIVE, the Pi screen says “Could not parse the album URL”, and the logs say No images found on views/usbstorage folder.

When I had mistakenly set GALLERY_URL to USBSTICK, the logs said error: Could not parse album.

I’m doing this on a Pi3 with the 7" screen.


the links you added and the errors are making sense
here you see the GALLERY_URL indeed needs to be USBDRIVE
In the same repo there is an example what can be the value of the CRON_SHEDULE.

The contents from your USB should be copied to the folder mentioned in the error.
See photo-gallery/copy.sh at 142145c43bc8d5ddfdb08a462062a36d8e008b11 · balenablocks/photo-gallery · GitHub

Can you check if there are extra folders, or access rights blocking the copy?

I set the CRON_SCHEDULE to 0 */12 * * * and views/usbstorage eventually reported having images, but I had to restart kiosk to get the images to display.
I’m not sure that setting the schedule was the cause, as server.js also sets the schedule to that value as a default.
I suspect that the usb has to be inserted after the pi initializes, and then takes some time to load them.