Saving your WRTnode

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Download the WRTnode firmware

Two commonly used methods of refreshing firmware are provided in Refresh the firmware section, these 2 methods are using the WiFi connection to transfer the firmware to WRTnode. If for some reasons the WRTnode is not working anymore - cannot connect/control it over the WiFi connection (it was bricked), we have to restore it to a functional state (to debrick it).

Below it will be presented other two different connection methods to the WRTnode for the situations when the kernel is not starting (OpenWrt is not able to boot) and/or for the situation when WiFi connection is not available. For both methods a cable is used to connect to WRTnode development board.

The cable used to connect to the WRTnode is basically an Ethernet cable (T568B pinout) at one end (it has an RJ45 connector) and at the other end has a 2x2 female header 2.54mm (Dupont headers) - we will call this cable "special cable". The special cable can be 50cm long (see Figure 1):

Figure 1

Special cable pinout:

As mentioned, a T568B cable pinout is needed. Table 1 contains the T568B pinout:


At the other end of the cable it is used a 2x2 female header 2.54mm which connects to the green, green and white, orange, orange and white wires from the cable. The other 4 remaining wires can be cut (brown, brown and white, blue, blue and white).

Table 2 explains how to connect the 4 wires to the 2x2 female header:


After that step, the special cable can be connected to the WRTnode.

The WRTnode pin map (Figure 2):

Figure 2

The special cable from the above images has a small black arrow on the 2x2 female header which is the mark for Pin1. WRTnode has male headers on the board and has 4 LAN ports connections on these headers, so the cable can be connected to any of these 4 LAN ports, the black arrow corresponds to pins 2,4,6,8 on the WRTnode (the Pin2 on the cable corresponds to pins 1,3,5,7 on the WRTnode). Example on Figure 3 is for pin 4 on the WRTnode.

Figure 2 shows as well the WAN port pinout on the WRTnode board.

Figure 3

1: When Uboot starts, enter the refresh firmware mode

You can refer to WRTnode U-Boot instructions

2: Serial connection (TTL levels - not RS232 levels!)

WRTnode board offers as well the classic serial port, see Figure 2 for Tx and Rx pinout. To access the serial ports, a serial-to-USB cable it is needed.

Connection between serial-to-USB wires and WRTnode pins

Serial-to-USB cable connected to WRTnode

Through the serial connection, the WRTnode can be debricked, basically flash memory modifications, debugging and other operations can be performed.

In order to use the serial connection, we need to know the port number of the serial-to-USB cable, we need to install as well a TFTP server and a serial software like PuTTY. 

Here is an example for a Windows system: serial-to-USB cable is using port COM3, The Uboot baud rate to 115200, the OpenWrt kernel baud rate also 115200 (see Figure 4).

PuTTY configuration for serial connection

Figure 4

After connecting via serial-to-USB cable to WRTnode board and powering up the board, we can see the boot messages and a choice menu will appear, from that menu we have to choose option 2 ("Load system code then write to Flash via TFTP"), that means to use TFTP protocol in order to download the firmware into the WRTnode while the special cable is still connected, then press "y" key (yes). Also following parameters must be provided:

Input device IP = (fill in the IP of WRTnode board)

Input server IP = (fill in the IP of the TFTP server, this IP and device IP must be part of the same network)

Input Linux Kernel filename = (The name of the firmware we want to upload via TFTP server)

Press enter key and wait for the firmware to load into the WRTnode and for the kernel to restart.

Note: if you cannot see the boot messages correctly or if the code is loading with errors into the WRTnode board, verify the baud rate to be consistent, also the cable must be checked for good electrical functionality. WRTnode original firmware baud rate is 115200 bps, OpenWRT baud rate is 57600 bps.

3: apcli configuration

About apcli configuration Click here