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Mikrotik RouterBoard 1xx


These boards come with a MIPS32 4Kc based 175MHz embedded processor, Infineon ADM5120.

There are currently 6 boards in this range:-

  1. 112 The original 1xx board, two mini-pci, 16MB RAM, 64MB NAND Flash, one ethernet, no CF
  2. 133 Three mini-pci, 32/16MB RAM, 128/64MB NAND Flash, three ethernet, no CF
  3. 133c One mini-pci, 32/16MB RAM, 128/64MB NAND Flash, one ethernet, no CF
  4. 150 No mini-pci, 32MB RAM, 64MB NAND Flash, five ethernet, no CF
  5. 153 Three mini-pci, 32MB RAM, 64MB NAND Flash, five ethernet, one CF
  6. 192 Two mini-pci, 32MB RAM, 64MB NAND Flash, nine ethernet, no CF

Most of these devices use just the build in ethernet switch in the ADM5120, but the 192 has an additional chip, the IP175C which provides an extra 4 ports. The ADM5120 switch handles ports 1-5 and the IP175C ports 6-9. NOTE that the Microtik documentation and the Microtik enclosure for the 192 differ on port numbering. This explanation follows the enclosure as it makes more sense when you look at the board and it seems easier that the AMD5120 supports 1-5 rather than 1,6-9. The current kernel supports all nine ports, but the ones supported by the IP175C act as a little switch of their own, all in one bridged group and are reported to the CPU as eth5. For discussion of the addition of support for the IP175 please see Ip175C. This chip is also apparently used in one or more of the RB4xx series boards.


Installing OpenWrt on these boards (apart from the 153) is only possible by using the NetBoot facility. For this you will need:

  1. A serial connection with a null modem cable as console (standard serial cable will not work).
  2. An ethernet connection to load the NetBoot kernel and then download the NAND image.
  3. A DHCP server to tell the RB1xx where to get it's netboot image. This can be done either using independent packages or using DnsMasq.
  4. A TFTPD server to supply the NetBoot image to load a barebone OpenWrt RAMdisk image. You will boot into the RAMdisk version of OpenWrt and use it to flash the permanent OpenWrt image into NAND.
  5. A Web server to serve up the permanent version of the OpenWrt kernal and rootfs.

The minicom settings for a connection using a USB serial port would be:-

# Machine-generated file - use setup menu in minicom to change parameters.
pu port             /dev/ttyUSB0
pu backspace        BS
pu baudrate         115200
pu bits             8
pu parity           N
pu stopbits         1
pu scriptprog       /usr/bin/runscript
pu minit
pu mreset
pu mdialpre
pu mdialsuf
pu mdialpre2
pu mdialsuf2
pu mdialpre3
pu mdialsuf3

You can also use Windows' Hyperterminal for the serial console.

Setting up DHCP/TFTP server

You will need a DHCP and TFTP server to be able to Netboot the RB1xx. For ISC dhcpd implementation, such configuration file will be ok :

# Sample configuration file for ISC dhcpd for Debian
# $Id: dhcpd.conf,v 2002/07/10 03:50:33 peloy Exp $

# option definitions common to all supported networks...
option domain-name "";
#option domain-name-servers;

#option subnet-mask;
default-lease-time 600;
max-lease-time 7200;

ddns-update-style none;
subnet netmask {
        option domain-name-servers;
        option domain-name "";
        option routers;
        default-lease-time 600;
        max-lease-time 7200;

        host rb {
                hardware ethernet 00:xx:xx:xx:xx:xx;
                filename "/tftproot/openwrt-adm5120-2.6-vmlinux.elf";

Where "next-server" is the IP address of the TFTP server, which is here, the same IP address as the DHCP server as well. You may need to rename the vmlinux.elf file by adding the "-2.6-" so it matches the DHCP settings above.

Building OpenWrt for RB1xx

Unfortunately you need to build two kernels in order to install OpenWrt. The first has a RAMDISK based file system and will use NetBoot for startup. It will be used to install the second image–the permanent one that will be flashed into NAND and will be your running OpenWrt kernel.

To compile your OpenWrt firmware images you need to download an SVN copy of OpenWrt Kamikaze, and then run make menuconfig.

In menuconfig select the "ADM5120-2.6 (Little Endian)" target. Then in the Target Images section select RAMDISK. This will disable all the other image options. There is no need to make package selections at this stage as all the packages you will need to install the system are there by default.

Save the configuration and run make (this will take a while).

You should now have a file in the bin directory called openwrt-adm5120-2.6-vmlinux.elf, and this should be copied to your TFTPD root directory, the same as mentionned in "dhcpd.conf". Check the spelling of this file closely, NetBoot will be looking for the above file with the "-2.6-" in it.

Starting the RAMDISK image

With your serial console ready, power on your RB1xx board. Press "Enter" within 2 seconds to make it stop the autoboot process. You can now see the following boot loaker menu :

RouterBOOT booter 2.1

RouterBoard 112

CPU frequency: 175 MHz
  Memory size:  16 MB

Press any key within 2 seconds to enter setup.

What do you want to configure?
   d - boot delay
   k - boot key
   s - serial console
   o - boot device
   u - cpu mode
   r - reset configuration
   e - format nand
   g - upgrade firmware
   i - board info
   p - boot protocol
   t - do memory testing
   x - exit setup
your choice:

Press "e" and type "yes" to format the NAND memory, this must be done to free up memory for the new kernel and file system.

Press "o" to select your boot device. Then you will see this menu :

Select boot device:
  * e - boot over Ethernet
   n - boot from NAND, if fail then Ethernet
   1 - boot Ethernet once, then NAND
   o - boot from NAND only
   b - boot chosen device
your choice:

Choose "e" to boot over Ethernet, or "1" to boot over Ethernet once, then boot from NAND thereafter.

Select "x" to exit and boot from Ethernet now.

Build the running image

Now you need to build the final running image, and for this you will need to run make clean (to get rid of the old settings) and then run make menuconfig again. This time select TAR as the Image type. You should also go through and select the packages that you want (although you can always add them later with ipkg). Once you have completed the configuration you can save and exit, then run make (and once again wait a while).

This time you will find a tar file in the bin directory called openwrt-adm5120-2.6-rootfs.tgz and the kernel called openwrt-adm5120-rb1xx-kernel. (If for some reason you don't find the kernel in the bin directory, the one called build_dir/linux-adm5120_router_le/vmlinux.elf should also work.) Copy these two files into a directory which can be reached by your web server as openwrt-adm5120-2.6-rootfs.tgz and openwrt-adm5120-2.6-kernel. Again, verify the name of this file, you may need to add the "-2.6-" to the file name.

Flash the running image

Now you can power up your RB1xx and it will boot the RAMdisk version of Openwrt over the ethernet. When the RAMDISK Openwrt kernel is booted hardly any of the normal OpenWrt initialisation occurs - you will not find that modules have been loaded or the network configured. In /sbin however you will find a script called wget2nand which will do the installation for you, using the second kernel and the flash image.

wget2nand takes a single parameter, the URL of the directory into which the tgz and kernel files were stored. wget2nand assumes you are still running DnsMasq (or whatever was your Bootp server) and that it will also serve addresses using DHCP.

When you build Openwrt using the trunk the NAND kernel image file needs to be renamed, you have to add the "-2.6-" to the name. wget2nand looks for a kernel file called "openwrt-adm5120-2.6-rb1xx-kernel" The rootfs file name is correct and does not need to be changed.

At the Openwrt command prompt, run:


to flash Openwrt to NAND. This command assumes the kernel and rootfs files are stored in the web server root. Substitute your http server's address for ""

If wget2nand does not work for you, see the [#head-b8817b9d50b5e02079e208b41b684656cfbfece1 Manual flashing] section below.

When you reboot you need to change the BIOS settings back to booting from the NAND.

Once the installation is complete you can reboot your RouterBoard 1xx and you should have a running system.

Manual flashing

wget2nand was broken, but as of r10221 it should work. If you are trying an older revision or wget2nand still does not work and gives you a "Cannot find NAND Flash partitions" error like this:

root@OpenWrt:/# wget2nand
killall: udhcpc: no process killed
udhcpc (v1.8.2) started
Sending discover...
Sending select for
Lease of obtained, lease time 43200
adding router
deleting old routes
adding dns
Cannot find NAND Flash partitions

You will need to format the flash from the BIOS and then do the extractions manually, as follows:

A quick HOWTO to get things going is over here. I did not need to install the RedBoot version mentioned on that page.)

root@OpenWrt:/# mount /dev/mtdblock2 /mnt
yaffs: dev is 32505858 name is "mtdblock2"
yaffs: passed flags ""
yaffs: Attempting MTD mount on 31.2, "mtdblock2"
root@OpenWrt:/# cd /tmp
root@OpenWrt:/tmp# wget
Connecting to (
openwrt-adm5120-rb1x 100% |*******************************|  2381k 00:00:00 ETA
root@OpenWrt:/tmp# mv openwrt-adm5120-rb1xx-kernel /mnt/kernel
root@OpenWrt:/tmp# umount /mnt
save exit: isCheckpointed 0
root@OpenWrt:/tmp# mount /dev/mtdblock3 /mnt
yaffs: dev is 32505859 name is "mtdblock3"
yaffs: passed flags ""
yaffs: Attempting MTD mount on 31.3, "mtdblock3"
root@OpenWrt:/tmp# wget
Connecting to (
openwrt-adm5120-2.6- 100% |*******************************|  1599k 00:00:00 ETA
root@OpenWrt:/tmp# cd /mnt
root@OpenWrt:/mnt# tar xzvf /tmp/openwrt-adm5120-2.6-rootfs.tgz
root@OpenWrt:/mnt# cd /
root@OpenWrt:/# umount /mnt
save exit: isCheckpointed 0


oldwiki/openwrtdocs/hardware/mikrotik/rb100.txt · Last modified: 2011/12/27 11:34 (external edit)