lsusb
...
Bus 001 Device 005: ID 0922:8000 Dymo-CoStar Corp.

This confirms OS know USB port.

Install the HID driver we needed:

opkg update 
opkg install kmod-usb-hid
...
Configuring kmod-input-core.
Configuring kmod-input-evdev.
Configuring kmod-hid.
Configuring kmod-usb-hid.
...
cat /dev/usb/hiddev0  | hexdump
0001c50 008d 0073 0000 0000 008d 0074 0000 0001
0001c60 008d 0041 ffff ffff 008d 0040 0000 0039

0039 in Hex is  57 in DEC, my Iphone weight 5.7 Oz.

cd /mnt/sda1
wget https://www.dropbox.com/s/uwy1d0lgawljf3b/evdev.py --no-check-certificate
chmod 755 evdev.py
./evdev.py '/dev/usb/hiddev0'
...
<Event timestamp=9244935.9672950006 type=141 code=64 value=57>
...