At last… freedom!
In standard configuration the La Fonera+ wireless router has Telnet and SSH turned off. By accessing the integrated serial console, SSH can be turned on and various settings can be accessed. Moreover this also enables re-flashing the firmware. The only thing needed is a TTL to RS232 level shifter to connect it to a PC.
Any kind of TTL to RS232 level shifter will do the job. If you want to build your own, then for example a MAX232, MAX3232 or DS275 IC could be the chip of your choice. However, if you don’t have such chip in your collection or you can’t wait until it will arrive in your mailbox then you can make a simple console adapter using only NPN transistors, a few resistors and a diode.
Materials used
- D-sub 9-pin serial female connector
- 2x BC847
- 4x 1K resistor
- 1x 2K2 resistor
- 1x 1n4148
- some wire
- etched pcb
Design
The design of the pcb is straight forward and simple. The only thing I had to keep in mind was the available space inside the FON. In order to save space I build the circuit with SMD components. The completed circuit board found a suitable place inside the FON, clearing the two capacitors and the LED light ducts mounted on the top panel.
Building
The whole process, from designing the circuit on my laptop up to installing the finished pcb in the FON, took only three hours. It was a quick and simple job without any complications.
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Looks nice!
I’m also glad to report that the flashing worked flawlessly with this interface.