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I'm trying to access the serial port of my B3. I've followed the guide on the wiki, except that I'm using a pl2303 usb-to-serial converter. When I connect all I get is garble. Is the pl2303 incompatible or am I doing something else wrong?

the standard problem when getting garble (then you are at least getting something) is that you set the speed wrong. You an also try resetting your terminal, since it can get out-of-sync. Third possible problem is that the ground wire is missing or poorly connected. Get back if you don't get it working.

Here is the settings I tried:
Baud rate: tried every setting from 300 to 927600 (including 115200, as suggested by the wiki).
Data bits: 8
Stop bits: 1
Parity: none
Handshake: tried both none and software

I've just spent some time to clean all the contacts on my improvised serial connector, but I still have the problem. The total resistance of the ground connector between the two devices is about 0.3 ohms, if I'm reading the meter correctly. I don't know if that is a lot; I don't normally work with hardware.

Strange, seems you are doing it right. 115200 and no handshake is correct settings. Also 0.3 ohm is probably what you are getting if you would connect your meter probes directly together, so that's good.

Another thing would be if your serial - to - usb adapter has the wrong voltage, it has to work at 3.3V signalling speeds. Could that be it? Otherwise, try connecting hte TX and RX together at your USB serial adapter, and see if it echos. Then you can do the same with the B3 to check. Hopefully this brings you closer to the issue.

Hello,

The PL2303 is a converter between USB and standard RS232 serial port. It is not compatible with the TTL 3.3V console port on the B3. You need to use another adapter, such as the FTDI TTL-232RG-VREG3V3-WE, available in sereral online shops.

Thanks. I added a max3232 to convert the voltage levels and it's working now.

Unfortunately, the max3232 requires a 3.3V source (currently I'm using an external source). Is there an open solder-able contact point on the B3 board that would supply 3.3V?

This is just for convenience sake; if it's not possible to get the power internally, I can just continue using the external source.

Hopefully everyone is back from holiday. Is there any response for my question above? (Is there an open solder point on the B3 board that would supply 3.3V?)

max3232 can also handle 5V power supply and lucky for you, this comes right from your USB port