can't download Oceanic VT3 on linux

[Jef Driesen]

On 2014-03-11 16:59, Linus Torvalds wrote:
> On Tue, Mar 11, 2014 at 6:27 AM, Jef Driesen <jef at libdivecomputer.org> 
> wrote:
>> 
>> I wonder if this is another case where the tcdrain() function isn't 
>> waiting
>> properly until all bytes have been send out.
> 
> Assuming it is ftdi, we should have at least *tried* to do it since
> 3.8, but I really won't guarantee that it works. I'm assuming Hamish
> has something newer than that, but who knows.. As usual, I think
> Debian "stable" (also known as "bat shit crazy") is some ancient 3.2
> kernel still, but all other distros should be much more up-to-date.
> 
>> We had a similar problem with Suunto devices before.
> 
> As you know (but perhaps others don't) this isn't a Suunto problem per
> se -  the actual *real* legacy serial cable should work fine, because
> on a real UART we generally have an easy way to check whether the send
> buffer has actually flushed out.
> 
> But the USB people originally (consciously) decided to not make USB ->
> serial be a standard, because their argument was that USB should
> replace serial lines, and USB serial dongles were thus "invalid".
> Morons with an agenda. As a result, there is no actual standard USB
> serial conversion model, and every single USB serial chip is a "hack"
> pretty much by definition.
> 
> And with simplex being *so* unusual, it doesn't get a lot of attention
> and testing, and since it's not some generic standard, it's always
> per-dongle-chip-driver.

With USB being the Universal *Serial* Bus, it's kind of funny that one 
thing it doesn't do very well is serial communication :-)

Isn't USB CDC-ACM supposed to be the standardized way for emulating 
legacy serial communication over USB? There are a few dive computer 
using it (Mares Icon HD and Dive Rite Nitek Q), but these are all using 
a microchip internally. So although they do present themselves to the 
outside as a legacy serial port, at no point there is any conversion to 
real serial communication necessary (because that microchip speaks 
native usb). So that's quite different from using a usb-serial 
conversion chip from ftdi or prolific, which really has to emulate 
serial communication on one end.

Jef