usb serial in diagnostic

Probably that would be the way to flash rom.

It seems to be used for reparing the device or OS level software debugging - it won't give you USB Mass storage device....Or it maybe if you found the right driver...from Nokia Engineer. On HTC phones, this can be used for tethering with the right driver.

Serial Ports are the port that were used for Modem and Mouse before USB was invented (COM ports) It is the very basic form of communication port that most device implements - which the chipset on Lumia also emulate Serial Port over USB cable. (http://en.wikipedia.org/wiki/Serial_port)

Didn‘t notice that before, I'll poke at it using a serial debugger once I get home, could be some interesting/fun stuff that can be done

In winxp you can load a driver for a system device. maybe at driver level the connection data can be verified. How:
connect in serial mode. it will at first time detect a nokia rm801 or whatever device and ask for a driver. it finds 4 devices.

for the first, the xp system will itself suggest
1) USB Composite Device
2) will not find anything, and show the dialog to go onto internet, search etc.
Don't search and choose the driver to install yourself, with the downmost radiobutton and click next, in the categories go to System Devices, the driver assist will suggest a Compaq Deskpro Thermal Sensor, install this. Will install without error
3) see 2.
4) see 2.

Because it installs a temperature sensor driver, it must be possible to monitor or probe somehow. help?

My guess that will only gain you access to temprature data from the phone.

Have you tried putty and a baudrate of 9600? this is the most common used baudrate, tho It is quite possible they use 16000 instead if the serial connection is ment to handle data transfer.

I've been looking at the schematics for the phone and I can not seem to find out which chip they have used for GPIO. We would probably need to get hold of service level 3 or 4 manuals for Nokia Care (unless someone wants to dissasemble their phone and have a look at the mainboard)


Edit:

After a bit more digging I think I've traced serial to be managed directly by the CPU.
This suggests that it's a purely SW serial console.
I haven't been able to find any details on WP7/7.1/7.5 SW serial.

Worth looking into but I guess would require disassembly of the software?

what is the protocol for example when doing a software update through Zune? It gets into some kind of bootloader mode then too.
can imagine the serial connection is hosted as sw in the phones sw environment when running the mango os. But is the serial mode still fully sw if you boot it? Don't know if you could find anything in the 15 sec of booting to mango

I think the easiest way of figuring out how this is done is to disassemble the .net library that is used in the WP7 update tool.

I will have access to the required tools when I get home. The tool is this one if you want to get cracking on it:
http://xboxmod.sylvester20007.com/TOOLS/WP7_update_tool.rar