Is merely possessing a serial cable the answer to debricking

[Ian]

Everywhere I search, I am faced with the ultimate solution to debricking bricked plug computers: get a serial cable.

Let’s assume I have one (I have – two bits of wire, soldered to the serial terminals, solder-side, and poking out of the reassembled Pogoplug case, and these connect to a Sparkfun FTDI basic breakout with the addition of hooking the earths together by crocodile clip). Surely the mere ownership of a serial cable isn’t alone going to do the trick? I’ve had this serial cable arrangement for over a month or so now, and no progress has been observed. Am I supposed to do something with the serial cable? This is never ever mentioned. All references to debricking stop at the ultimate step of obtaining a serial cable as if that solves everything and I can lean back and allow the mere possession of a serial connecting method put everything back to normal again. Apparently the final step is to simply furnish oneself with a serial connection and go no further. This is exactly the situation I am in — going no further. One would almost imagine there might be some occluded further step beyond mere ownership of wires.

Technical stuff: My computer is a MacBook running Snow Leopard, my older computer is an iBook running Leopard. My Pogoplug is the magenta sort. I’ve used the FTDI basic breakout to do things with a breadboard arduino before giving up on the incomprehensible programming language, but at least the connection works: with the correct mumbo-jumbo in the “code”, data can be viewed on the Mac, in Terminal.

[peaslaker]

What you do depends on how thoroughly you have bricked the device.

If a runnable U-Boot image is present on the box (i.e. some flashing LED action), then a serial console can be run. On a mac you can use the 'screen' command and you need to have drivers for your FTDI (never used one). With the FTDI plugged into the mac, there should be a device node for it (usually /dev/tty.usbserial-xxxxxxxx, where xxxxxxxx will be a serial number or whatever the FTDI documentation tells you)

The terminal command will then be something like:
$this->bbcode_second_pass_code('', '
screen /dev/tty.usbserial-xxxxxxxx 115200
')

To get out of 'screen' and close down the driver, you need to use the key sequence CTRL-A CTRL-\ and then say 'y'.

My experience with a PL-2302 based serial cable is that the chipset in the cable is powered by the Plug and this connection needs to have been established before plugging in the USB side of things, otherwise you get nonsense. YMMV.

Once the serial connection is established and you can see U-Boot in action, the real debricking can begin. If however you don't have a running U-Boot instance (usually indicated by no flashing LED of any sort), debricking will require a JTAG interface (and instructions). If you thought serial was hard...