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Re: [gpsd-dev] Initialization & probing questions

From: Kai Harrekilde-Petersen
Subject: Re: [gpsd-dev] Initialization & probing questions
Date: Tue, 27 Mar 2018 22:39:31 +0200
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0

Hi Gary,

On 26-03-2018 23:44, Gary E. Miller wrote:
Yo Kai!

On Mon, 26 Mar 2018 22:28:59 +0200
Kai Harrekilde-Petersen <address@hidden> wrote:

I'm trying to implement the Skytraq driver the 'right way', going by
the comments in driver_proto.c and referencing the Ublox driver.
Why not build on the existing Skytraq driver?  It works for Venus 6.
I did, and I do, but the existing driver was missing a several things (including not detecting my GPS and it had no way to configure it through gpsctl) so I was beginning to rewrite parts of it.
I've now added bin/nmea mode, cycletime and baudrate handling to it.
1) If I send a command, how should I wait for the response before
You don't, can't, should not.
Good, this is what I expected.
3) Excessive probing time.
Since the Skytraq powers up at 115.200 baud, it takes an obscene
amount of time for it to be probed (asĀ  584 sec. Yes, almost 10 min!).
Which is why we always recommend to set the GPS to the right serial
port speed before starting gpsd.
stty -F /dev/ttyS0 115200
Ah, I must have missed that memo. I found that stty command myself just the other day, but wanted to make sure I wasn't missing something obvious.
4) Store/restore of device settings.
The skytraq allows to to probe its settings to hearts' content, which
allows me to restore the state when deactivating.
You could, but then that makes other things hard.  I prefer to just leave
the GPS as is on exit.  Makes debugging easier.  Opinions vary.

Good. Less work :)

The modified driver should work for both the Venus6 & Venus8 now. Do you want patches directly for testing on the Venus6 or should I post them to the list?

One question related to gpsd.h: I noticed that SKY_PACKET is placed at the end (20), but from looking at the other macros, it looks like it should be SKY_PACKET <= MAX_GPSPACKET_TYPE, otherwise it won't be picked up by GPS_PACKET_TYPE(n) and missed by PACKET_TYPEMASK(n) and GPS_TYPEMASK. I changed SKY_PACKET to 16 and bumped the following and at least for the Skytraq it works correctly.

Best regards,


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