Testing ftdi code

[Anton Lundin]

On 04 October, 2016 - Willem Ferguson wrote:

> On 18/09/2016 10:48, Anton Lundin wrote:
> >After the last round of custom serial rewrite, the ftdi custom serial
> >code now can be used with all libdivecomputer backends, and not just
> >OSTC3.
> >
> >I thought its time to share how this works so more developers can test
> >different backends with the ftdi code.
> >
> >
> >1. Start by installing libftdi1. Either download the source from
> >http://www.intra2net.com/en/developer/libftdi/download.php and build it
> >yourself (only c library is needed, see packaging/android/build.sh for
> >ref.) or install it from your package manager. In debian/ubuntu the
> >relevant package is libftdi1-dev.
> >
> >2. Build subsurface with FTDI support by calling cmake with
> >-DFTDISUPPORT=ON
> >
> >3. Plug in your ftdi device/cable and chown the usb character device
> >your test user. lsusb will give you bus / device and the device is found
> >at /dev/bus/usb/$bus/$device . This can be automated with udev.
> >
> >4. Open the regular download from divecomputer dialog and choose vendor
> >/ device. Instead of entering a serial port, enter "ftdi" in the "Device
> >or mountpoint" filed.
> >
> >5. Click download, and the custom serial code will kick in, using the
> >first ftdi device it finds.
> >
> >
> >There are probably a bunch of usb vid/pid's missing so if you know that
> >your device uses ftdi, you can add those vid/pid's to
> >core/serial_ftdi.c: serial_ftdi_open_device(...) and to
> >android/res/xml/device_filter.xml.
> >
> >
> >Note. The libftdi code doesn't make sense on regular systems, where a
> >good native serial<->usb driver is already available, but it rather
> >makes sense on Android, where we don't have any kernel driver for ftdi.
> >
> >This way we can test the code on regular machines, before testing it on
> >Android. Its way easier to debug on a regular machine.
> >
> >If you're feeling adventurous, you can build Subsurface desktop for
> >android and do the exact same things on Android. I suggest using a mouse
> >to navigate the ui.
> >
> >
> >//Anton
> >
> >
> 
> Anton,
> 
> I am now starting to work with this. But need a bit of help.
> 
> 1) I do not use cmake directly (I'm far too dumb for that) but use
> the build.sh script for building subsurface. I assume I can add the
> -DFTDISUPPORT=ON to the call on line 245 of the build script?
> 

Yep

> 2) How does Linux see the USB character device? Where would I find
> it? By using dmesg like for other USB devices?
> 

lsusb , ls /dev/bus/usb/$bus/$device .

> 3) Where does one find the vid/pid information for the ftdi device?
> 

If a vendor uses a custom vid/pid its hard to say. The most complete
list i know of is:
https://github.com/torvalds/linux/blob/master/drivers/usb/serial/ftdi_sio.c#L142

That said. I think we should only add custom vid/pid's that we know dive
computers use.

> 4) I assume   android/res/xml/device_filter.xml is irrelevant for
> building and executing on Linux (Ubuntu 15.04 or F22)?
> 

Yes.


There is no reson to use the libftdi code on linux other than to test
the implementation or different ftdi-cables. It's only real use case is
where real kernel drivers doesn't exists, ie Android.


//Anton


-- 
Anton Lundin	+46702-161604