OC1 usb connection

[dennypage]

Nick,

I'm having what appears to be a common connection problem with the Oceanic OC1.

My error is:

Failed connecting to dive computer on serial port '/dev/tty.usbserial-20030001' (Error Code: -6)

I have read forum entries that suggest that this is a cable connection problem and that what is necessary is to jiggle the cable and to try again. After almost three hours of experimentation, I do not believe that this is a cable issue.

I have tested two different (brand new) OC1s, with three different cables, on two different computers, with Mac OS 10.6 and 10.7. I tested MacDive (native) and Oceanic's OceanLog under VMware.

OceanLog worked each and every time with all combinations of PDC and cables. MacDive on the same computer failed to establish a connection approximately 80% of the time. Cable jiggling/wiggling/etc. did not affect connection success rates. Retrying the connection over and over was all that mattered.

My speculation was that there is a timing issue with the initial handshake with the OC1 and that the mac is overrunning the OC1's receive buffer. To test this, I started loading the CPUs with free running apps, and started MacDive with nice. After doing this, the connection failure rate improved dramatically, dropping to around 30%.

I note that when the connection fails, the following is output from MacDive:

/Users/nick/Projects/DiveComputer/Mac/DiveComputer/../../src/oceanic_atom2.c:212: Unexpected answer start byte(s).
/Users/nick/Projects/DiveComputer/Mac/DiveComputer/../../src/oceanic_atom2.c:212: Unexpected answer start byte(s).
/Users/nick/Projects/DiveComputer/Mac/DiveComputer/../../src/oceanic_atom2.c:212: Unexpected answer start byte(s).

Perhaps a delay loop or two in the initial handshake would fix it?

If there is anything that I can do to help narrow if further, please let me know.

Regards,

Denny

[TnT]

Can you follow the instructions in this topic, to generate a detailed logfile?

[nick]

This topic:

http://www.mac-dive.com/forum/viewtopic.php?f=5&t=407

[dennypage]

Nick,

Apologies for the delay. Here is the file with results, both of a bad run (init fails) and of a good run (lots of output).

Note that there are no stored dives in the computer tested. I can hit the pool and put a dive on, but it will be late next week.

Regards,

Denny

[nick]

Thanks for this - let us take a look and see if we can't get this working a little better/more reliably.

[dennypage]

Nick,

I put a couple of dives on the device. Would you like an new upload?

Regards,

Denny

[nick]

Yes, please - the more the merrier!

[dennypage]

Nick,

I've isolated the timing issue in libdivecomputer, and sent an email off to Jef regarding a fix. Email is below for your reference. Please let me know if you would still like the sample files.

Regards,

Denny

-----

Jef,

I've been diagnosing a problem with MacDive and the Oceanic OC1. You can view the forum thread here:

http://www.mac-dive.com/forum/viewtopic.php?f=2&t=965

I pulled the current git repo and did some further experimentation to isolate the problem. There does appear to be a timing problem with the initialization routine for the computer. In oceanic_atom2_init(), we send an initial command sent to the device, followed by a check for an acknowledgement. After the acknowledgement is processed, we call to serial_flush() to discard any additional bytes sent by the device after the ack. The device appears to send quite a bit of additional data, resulting in a race condition between the device sending bytes related to the initial command and the call to serial_flush(). The solution is to add a delay prior to the call to serial_flush(). The diff is below.

Regards,

Denny

-----

diff --git a/src/oceanic_atom2.c b/src/oceanic_atom2.c
index 8465eef..177c045 100644
--- a/src/oceanic_atom2.c
+++ b/src/oceanic_atom2.c
@@ -259,14 +259,15 @@ oceanic_atom2_init (oceanic_atom2_device_t *device)
// Send the command to the dive computer.
unsigned char command[3] = {0xA8, 0x99, 0x00};
device_status_t rc = oceanic_atom2_send (device, command, sizeof (command), NAK);
if (rc != DEVICE_STATUS_SUCCESS)
return rc;

// Discard all additional bytes (if there are any)
+ serial_sleep (1500);
serial_flush (device->port, SERIAL_QUEUE_INPUT);

return DEVICE_STATUS_SUCCESS;
}


static device_status_t

[nick]

Can you also drop me an email - I will apply your patch after work and send through a beta for you to try, to see if that helps out?

It does need to be tested with various other devices, however.

[tinyhunter]

With the new Macdive version, connecting to the OC1 does work much better.
Thanks dannypage that you took time to look into it....