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RB433UL: how to use the serial connector pads

Posted: Thu Aug 29, 2013 5:25 pm
by larser
Hi,

I just bought a RouterBOARD 433UL in order to try if it is suitable for our local wifi community network.

The 433UL contains only pads for RX/TX/GND/3.3V instead of a physical RS232 connector. Thus I soldered wires onto these four pads and connected them with 3.3V serial converter.
Sadly I did not notice any output during the bootup procedure of the device.
I configured the serial port with 115200 8N1 (later also with 9600 and other baudrates). I used different serial interface programs (screen, gtkterm). I also swapped RX/TX both ways to make sure that the cabling is correct.
Afterwards I went through the wiki (e.g. Serial Console) without gaining further insights.

Did anyone of you use the serial interface of the RB433UL? Maybe I missed some jumper settings or special setup procedure?

Thank you for your time!

cheers,
Lars

Re: RB433UL: how to use the serial connector pads

Posted: Mon Sep 02, 2013 4:38 pm
by janisk
This router does not have a hardware required for console to work also, it is not initialized and thus, not available in software even when presented with required hardware as OS is instructed to not to look for such port.

If you require console access better opt for the device with port already present at the time of purchase to avoid all this hassle.

Also, console is not required to manage the router as there are tools and procedures on how to operate the router without console port - via MAC-telnet or mac-winbox tools that allow access to the router that is not configured. If everything is broken (locked yourself out of router via configuration) you can force router to reinstall over network using netinstall tool etc.

Re: RB433UL: how to use the serial connector pads

Posted: Mon Sep 02, 2013 5:52 pm
by larser
Thank you for your reply!
This router does not have a hardware required for console to work also, it is not initialized and thus, not available in software even when presented with required hardware as OS is instructed to not to look for such port.
Out of some weird mood I spend another hour with the RB433UL and discovered that indeed the electrical part of the serial console is working.
The downside is that you need a kernel from openwrt to enjoy this feature :(
Basic procedure:
  • hold reset button during bootup
  • provide DHCP and tftp services suitable for booting from the network
  • feed an openwrt image build for RB433 via tftp
As soon as the kernel is transmitted, you will see the kernel boot message via the serial console with 115200 baud.

But anyway: this is not the original firmware, thus your answer is valid.
If you require console access better opt for the device with port already present at the time of purchase to avoid all this hassle.
Yes - I learned that lesson :(
It is just that these RX/TX/GND/3.3V pads looked too promising to me ...

Also, console is not required to manage the router as there are tools and procedures on how to operate the router without console port ...
Our local mesh community uses firmware based on openwrt. Thus I need the serial console to adapt the current RB433 openwrt images to the new RB433UL product. Of course this is not necessary anymore as soon as this initial work of porting is done ...

Again, thank you for your response.
Lars