Problem with reading data from a "Scubapro Chromis"

[Jef Driesen]

On 14-07-15 17:27, Patrik Martinsson wrote:
> I'm trying to get my "Scubapro Chromis" to work with "libdivecomputer", 
> but it
> doesn't seem to work.
> Is this tested with a real "Scubapro Chromis" or is the support "just 
> added on
> belief that it should work" (I noticed that the support was added a 
> couple of
> months ago for the Chromis) ?

The rule of thumb is that a device only gets added to the list of 
supported devices if I receive data from at least one successful 
download. But for the Chromis, the only information I got is the new 
model number, and that the communication protocol and data format should 
be identical to the Meridian.

So it should work, but in this particular case I can't guarantee 
completely.

> This is what I get when I try to dump the memory from the Chromis,
> 
> ./universal -n "Scubapro Chromis" -b "meridian" /dev/ttyUSB0

You forgot the "-v" to enable a more verbose log with the I/O. But no 
worries, I already got that from your post to the subsurface mailinglist 
:-)

> DATETIME 2015-07-14T14:07:51Z (1436882871)
> VERSION 0.5.0-devel (0158739bcff3c4c3f8944e6e06932d836821cf28)
> Opening the device (Scubapro Chromis, /dev/ttyUSB0).
> ERROR: Failed to receive the header. [in uwatec_meridian.c:111
> (uwatec_meridian_transfer)]
> Registering the event handler.
> Registering the cancellation handler.
> Downloading the memory dump.
> Event: progress 0.00% (0/4294967295)
> ERROR: Failed to receive the header. [in uwatec_meridian.c:111
> (uwatec_meridian_transfer)]
> universal.c:795: Error downloading the memory dump.
> Result: Timeout
> 
> I would be surpriced if there was something wrong with the watch, 
> however that
> is of course possible.
> 
> Looking at the code I can see that there is an "echo" that is being 
> received
> before the header, so something is going on right (or am I missing 
> something) ?

You receive only the echo, but not the actual data packet. Echo's are 
often generated by the electronics in the PC interface, and not send by 
the dive computer. You can easily verify this by trying to download 
without the dive computer attached, only the PC interface. If you still 
receive the echo's, then they are not send by the dive computer.

Anyway, the important part is that the presence of the echo does not 
indicate there is some communication going on.

Have you ever tried to download your Chromis with the official Scubapro 
software (LogTRAK)? If not, can you try this? If that works, then we can 
already rule out hardware and driver problems. Next, try 
libdivecomputer's universal tool again on the exact same setup where you 
tried LogTRAK.

Jef