[maemo-developers] Unable to write to the serial port /dev/ttyS0 using, QextSerialPort on Maemo device

[From: Angel Perles]

I also considered QextSerialPort for the N900 (but I haven't started yet).

In my case, I will try to use the Bluetooth SPP profile (Serial 
Peripheral) that offers a Virtual COM port over Bluetooth.

I don't want to connect directly devices to the N900 in order to avoid 
breaking it, so I consider that this is a good option.

I utilized succesfully QextSerialPort on Linux and Windows with a 
Bluettooth-enabled GPS (that also uses the SPP profile), so I expect the 
same result with Maemo.

May be this "hack" guide could help you.

http://blogs.nokia.com/pushn900/wp-content/uploads/2009/09/PUSH_N900_Hackers_guidev1.0.pdf


I depends on what you want to do.

Regards,
Àngel


Suyash.Kumar at tieto.com wrote:
 > > OK, I understood, Thanks for the explanation Denis but I have one 
more question?
 > > IWe decided this approach as we have already implemented serial 
communication of Nokia N95 and PC (connected via USB cable). We simply 
used the symbian APIs for writing the information to the COM1 port and 
received the same on the windows PC's COM1 port and read it from there 
thus establishing a successful serial communication.
 > >
 > > That's why I was trying the same for Maemo. The serial port is not 
visible physically on N95 also but somehow we managed the serial 
communication between device and PC using this approach.
 > >
 > > Also, if the serial communication is not possible in this way, can 
you suggest me some other way/ sample code to achieve the same.
 > >
That wasn't really USB, it was RS232, with a wierd connector.

There are some RS232-over-USB-port capable phones - but absolutely no
desktop hosts support this.

Serial (RS232) and Universal Serial Bus - have about as much in common
as man and manatee.

You need to configure the n900s USB port to emulate a RS232->USB
converter - in some way.
http://www.kernel.org/doc/Documentation/usb/gadget_serial.txt is an
overview of how it would be setup.

Unfortunately, I'm unaware of how this would interact with the default
process that enables the requisite USB drivers.

I know hald-addon-usb-cable monitors the lowest level of this, and sends
an event on dbus, but I'm unsure what watches for this event, and
configures USB gadgets.


*************************************************************
Angel F. Perles Ivars

Departament d'Informàtica de Sistemes i Computadors - DISCA
Universitat Politècnica de València - E.U.Informàtica
Cami de Vera s/n. 46022-Valencia
Edifici 1G Despatx 2S-13
e-mail: aperles at disca.upv.es
Telf.+34 963877007 Ext. 75775 Fax.+34 963877579
http://www.disca.upv.es/aperles