Connect EV3 to hotplugged ethernet

EV3 ethernet hotplug

This is a small program for restarting DHCP on first interface for the EV3 programmable brick. This can be useful when you need to make the brick connect through a *supported* USB-to-Ethernet adapter to a wired network and you don't want to wait for a restart.

How to build:

- Get a copy of EV3 assembler (lmsasm) - my modified version can be found on https://github.com/JakubVanek/ev3sources-asm
- Download connect.lms to the directory with file assembler.jar from the step above.
- Compile this program. That is done by running "java -jar assembler.jar connect" in the assembler directory.
- Upload the connect.rbf file to the brick.

connect.lms

define OK_FREQ  1000
define OK_LEN   100
define ERR_FREQ 400
define ERR_LEN  250
define VOL      50
define YSPACE1  0
define DELAY    1000

vmthread  MAIN
{
  DATA32  Status
  DATAS   Command   60
  DATAS   Interface 10
  DATAS   Info      10
  DATA16  Handle
  DATA8   Empty
  STRINGS(DUPLICATE,'udhcpc -R -b -p /var/run/udhcpc.',Command)

  UI_DRAW(FILLWINDOW, BG_COLOR, 0, 0)
  UI_DRAW(UPDATE)

  SYSTEM('killall udhcpc', Status)
  SYSTEM('ifconfig -a | sed "s/[ \\t].*//;/^\\(lo\\|\\)$/d" >/mnt/ramdisk/interfaces 2>/dev/null', Status)
  FILE(OPEN_READ, '/mnt/ramdisk/interfaces', Handle, Status)
  FILE(READ_TEXT, Handle, DEL_LINEFEED, 40, Interface)
  FILE(CLOSE, Handle)
  FILE(REMOVE, '/mnt/ramdisk/interfaces')
  STRINGS(STRIP, Interface, Interface)
  STRINGS(COMPARE, Interface, '', Empty)

  JR_FALSE(Empty, run)
  UI_DRAW(TEXT, FG_COLOR, 0, YSPACE1, 'No interface!')
  UI_DRAW(UPDATE)
  JR(err)
run:
  STRINGS(ADD, Command, Interface, Command)
  STRINGS(ADD, Command, '.pid -i ', Command)
  STRINGS(ADD, Command, Interface, Command)
  SYSTEM(Command, Status)

  DIV32(Status, 256, Status)
  STRINGS(NUMBER_FORMATTED, Status, '%d', 10, Info)
  UI_DRAW(TEXT, FG_COLOR, 0, YSPACE1, 'dhcp:')
  UI_DRAW(TEXT, FG_COLOR, 50, YSPACE1, Info)
  UI_DRAW(UPDATE)
  JR_NEQ32(Status, 0, err)

  SOUND(TONE, VOL, OK_FREQ, OK_LEN)
  TIMER_WAIT(DELAY, Status)
  TIMER_READY(Status)
  JR(end)
err:
  SOUND(TONE, VOL, ERR_FREQ, ERR_LEN)
  UI_BUTTON(WAIT_FOR_PRESS)
end:
}

Meh, the following code works as well and is much more hassle-free:

ev3duder exec "udhcpc"
ev3duder exec "/etc/init.d/telnetd start"

One only has to stop the services before the brick is powered off:

ev3duder exec "killall -9 telnetd udhcpc"