Tom's Life Bits

Rembrandt is an embedded Linux processor based on the AVR32 AP700 and packaged in the Stamp form factor. It's the first of Tom's series of “Network Toys”.

• 32 Meg SDRAM
• 32 Meg FLASH
• Removable FLASH Media (SD card)
• 10/100 Ethernet onboard
• USB port

Rembrandt first boots the U-boot boot loader stored in parallel FLASH. The boot loader initializes the CPU, sets up the clock and initializes external SDRAM. It then loads the Linux kernel from the SD card and executes it.

This board lacks everything. There are no cables, hookup diagrams or even what to expect where. I watched the video and found that the Linux boot comes out of the DB9 232 port. I had a cable on the USB.

Connect a serial port to the DB9 connector on the NGW100 board with a straight serial cable (not a null modem cable). Open the comm software, select 115200,8,N,1,No Flow Control, and set up the terminal emulation as VT100.

The NGW100 has 2 ethernet ports. They are labeled LAN and WAN. Linux port eth0 is the WAN port and eth1 is the LAN port. They should have labeled this eth0 and eth1.

The default configuration for the NGW100 is to have eth0 attempt to seek a DHCP assigned address at start up, if it cannot find a DHCP server it will fall back to the address, 10.11.12.1

The LAN port, eth1, will default to an address of 10.0.0.1

To display the IP addresses that have been assigned to the NGW100 ethernet ports use the 'ifconfig' command.

   "ifconfig -a"

This will display information for both “eth0” and “eth1” as well as “lo”, the ethernet loopback port.

The NGW100 can be configured with a Static IP. The process is to shutdown the ethernet port, start it up again with a new IP and then add an entry in the routing table to the network's gateway. The last step is so the NGW100 will be able to see the Internet via the router.

To change the IP of eth1 use ifconfig.

To shutdown eth1 the command is:

   "ifconfig eth1 down"

To start it back up with an new IP of 192.168.1.87 the command is:

   "ifconfig eth1 192.168.1.87 netmask 255.255.255.0 up"

To confirm that eth1 has the new address the command is:

   "ifconfig -a eth1"

The NGW100 should now be able to ping other PCs on the network, be accessible via FTP and SMB at the new address etc. It will not however be able to access the Internet. For example it will not be able to access NTP time data to update the date and time.

To remedy this add an entry in the routing table that tells Linux where to find the gateway that allows access to the internet. In the current scenario the gateway is the router and hence is found at 192.168.1.1

To direct the NGW100 to this address execute the following command:

   "route add default gw 192.168.1.1"

If you want to see the routing table, execute this command:

   "route -n"

The NGW100 should now have access to the Internet. Test this by running “ping www.google.com” or by updating the date/time of the NGW100 by executing “/etc/init.d/S23ntp” and then “date” to confirm the date/time

The settings are lost when the system is rebooted. To make these permanent, edit the configuration files.

The boot sequence looks like this… CPU reset and runs the Bootloader.

   The bootloader runs and loads the kernel from the internal FLASH.
   The kernel runs and starts the init process.
   The init process runs starts the /etc/init.d/rcS script.
   The rcS script calls a bunch of other scripts to 
   initialize the  system and finally start the shell.

In the Trendnet router on Downing Place I added a firewall rule to allow access to 192.168.1.87. Host name is Rembrandt, ports allowed are 80-2210.

By adding a -p port parameter to S91httpd startup, the webserver is now at 192.168.1.87:9320

Nice web link for this document:
http://www.avr32linux.org/twiki/bin/view/Main/IdiotsGuideToAVR32

Rembrandt will contain a data logger which will record current data in a Round Robin Database (RRD). Open source RRD software writes data to an RRD and displays it in charts as well as fetches it for archiving to disk. See Tom's RRD notes.