Bug#640391: ark3116 driver regression: oscilloscope shows no transmission
I managed to get an oscilloscope onto the breakout box between the
garmin gps and the ark. This despite the oscilloscope deciding to
develop a video fault :-(
As I had suspected from the multimeter measurements, it seems
that the ark 3116 does not transmit *anything* under the
latest kernel (on the usual gpsbabel test).
Under the old working kernel, I saw packets in both directions.
For the record, the gps tx line was swinging between +5.6V and -5.4V,
while the ark3116 board was driving the gps rx line between 0V and 3.2V.
But under kernel 3.0.0-1, I could not get the 'scope to trigger
on either line, nor could see any activity.
So my conclusion is that the module is somehow setting the ark3116
into a mode whereby it cannot transmit if only the tx & rx (plus
grnd=pin5) are connected. Whereas the old version of the module
sets it up so that this is possible. Agree?
So rather than the gps failing to reply, it seems that the ark3116
never sends anything.
If I had had a little more time, and the 'scope did not keep dying,
I would have tried pulling the other lines up or down to see
whether transmission suddenly came to life.
I don't think there is now any point in trying a connection to an
ordinary serial port is there?
Is there anything else I can do at this stage?
ael
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