RPI U-boot run TFTP application

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Prerequisites (do once)

A "dual-homed" laptop or PC with:

• an RJ-45 (wired ethernet) jack
• a wireless connection

The strategy is to use a statically allocated ip address on the wired ethernet jack to connect to the RPI. The wireless connection allows access to the internet, Google, local devices on your LAN, etc.

Configure PC (do once)

see http://www.davidsudjiman.info/2006/03/27/installing-and-setting-tftpd-in-ubuntu/

• install tftp on PC

 sudo apt-get install xinetd tftpd tftp
 sudo mkdir /tftpboot
 sudo chmod -R 777 /tftpboot
 sudo chown -R nobody /tftpboot
 sudo gedit /etc/xinetd.d/tftp 
 [ add this entry]
   service tftp
   {
   protocol        = udp
   port            = 69
   socket_type     = dgram
   wait            = yes
   user            = nobody
   server          = /usr/sbin/in.tftpd
   server_args     = /tftpboot
   disable         = no
   }
 sudo service xinetd restart

• create a statically allocated IP address on the PC. I'm assuming your home network is 10.0.0.xxx based. Choose a separate subnet for the RPI to PC connection:

 Name      : RPI Connection
 Connect Automatically: unchecked
 IPv4 settings
    Method    : Manual
    IP address: 10.1.0.2
    subnet    : 255.255.255.0
    gateway   : 10.1.0.1 (or blank)
 IPv6 settings
    Method    : Ignore

• TODO: wireless does not work while RPI connection is up

Configure RPI

• attach an ethernet cable from the RPI to the laptop/PC RJ-45 jack
• attach the serial cable from the RPI to the laptop/PC USB port
• the following steps have to be done every time the RPI is reset

1. start the terminal emulator 2. start the USB subsystem. The ethernet jack on the RPI is on the USB bus

   U-Boot> usb start
   (Re)start USB...
   USB0:   Core Release: 2.80a
   scanning bus 0 for devices... 3 USB Device(s) found
         scanning usb for storage devices... 0 Storage Device(s) found
        scanning usb for ethernet devices... 1 Ethernet Device(s) found
   U-Boot> 

3. select "RPI connection" on your PC's list of ethernet connection 4. set the IP address on the RPI

   U-Boot> setenv ipaddr 10.1.0.3
   U-Boot> setenv serverip 10.1.0.2  

5. test the connection from the RPI (10.1.0.3) to your PC (10.1.0.2)

   U-Boot> ping $serverip
   Waiting for Ethernet connection... done.
   Using sms0 device
   host 10.1.0.2 is alive
   U-Boot> 

6. note: there is no ping server on the RPI, so you cannot test the connection from your PC (10.1.0.2) to the RPI (10.1.0.3)

• TODO: create script or command to preload all the above
• TODO: enable CONFIG_CMD_SAVEENV to enable saveenv command to save environment to FLASH; load at boot time

Load file using tftp

1. copy the image to load into the /tftpboot directory

  (on the PC)
  cd ~/projects/uboot
  cp build/examples/standalone/hello_world.bin /tftpboot/

2. load file using tftp

  (on the RPI)
  U-Boot> tftp 0x0c100000 hello_world.bin
  Waiting for Ethernet connection... done.
  Using sms0 device
  TFTP from server 10.1.0.2; our IP address is 10.1.0.3
  Filename 'hello_world.bin'.
  Load address: 0xc100000
  Loading: #
  done
  Bytes transferred = 594 (252 hex)

3. run the image

  U-Boot> go 0x0c100000
  ## Starting application at 0x0C100000 ...
  Example expects ABI version 6
  Actual U-Boot ABI version 6
  Hello World
  argc = 1
  argv[0] = "0x0c100000"
  argv[1] = "<NULL>"
  Hit any key to exit ... 
  
  ## Application terminated, rc = 0x0
  U-Boot>

TODO: enable CONFIG_CMD_TFTPPUT to try tftp puts (from RPI to PC)