Android to Autopilot

Discussion and support for the Nmea4Wifi multiplexer - a 4-input Nmea 0183 wifi multiplexer.
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mikeweston
Posts: 10
Joined: Fri Sep 25, 2020 5:26 pm

Android to Autopilot

Post by mikeweston » Thu Dec 03, 2020 7:33 am

I was hoping to interface an Android device to my Raymarine S3 Autopilot by means of the NMEA4WIFI and a custom app. My hope was to replicate the +1/-1/+10/-10 function of the autopilot controller. After recording some traffic from my Seatalk1 network, I discover that Raymarine (of course) uses a set of nmea083 unfriendly datagrams for this.

86 11 05 FA; -1
86 11 06 F9; -10
86 11 07 F8; +1
86 11 08 F7 ; +10

There are no NMEA0183 sentences that work for these. The S3 accepts a limited set of NMEA0183 sentences; HSC - Heading Steering Command; is not one of them. I could have simply added or subtracted from the current heading.

An option still remaining is to calculate the position of a waypoint (hundreds of miles away) that is on the heading I wish to steer, and send that to the S3 as an APB sentence. I am hesitant to do this. A minor code bug could cause a huge heading change that could be catastrophic downwind. I have been known to write very buggy code!

Can anyone think of a clever way to utilize the NMEA4WIFI device to insert a Seatalk datagram into the bus? I understand the N4W is not bi-directional Seatalk. There are some circuit designs that claim to allow insertion of datagrams from a RS232 source (http://www.thomasknauf.de/rap/seatalk3.htm#Bid) , but I have to get the data from the Android to such a device. I also don't see any collision avoidance logic in the circuit.

I have the Raymarine E85001 if that might be of any help. The N4W device will still be very useful in getting AIS to Android, even if I cannot use it for this particular project.

Cheers
Mike

Luis Sa
Site Admin
Posts: 845
Joined: Thu May 04, 2017 4:12 am

Re: Android to Autopilot

Post by Luis Sa » Thu Dec 03, 2020 8:21 am

Hello,

Thank you for your post. This would be a new project for me and I would need help in testing and developing. I just sent you a private email.

Regards, Luis

ttiburst
Posts: 5
Joined: Fri Jun 11, 2021 8:41 pm

Re: Android to Autopilot

Post by ttiburst » Tue Jun 29, 2021 8:02 pm

I have the same goal.

Did you make any progress on this project?

I was surprised about seatalk wiring.
I didnot understand how it can communicate both direction.
I read n4w can only receive seatalk information.

Is it right?

It is a pity.
Could we solve it with the e85001 box?
Reading the seatalk and answering on nmea0183?

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