A $20 Autopilot (Repost)

[Steelcat]

I have been using a windows computer software autopilot that I found.
It only requires a com port , relay board and GPS to operate.
It reads either $GPRMC or $GPVTG Baud 4800 and compares it to the set point then calculates an output that triggers Serial port DTR Pin 4 (steer to Port) or RTS Pin 7 (Steer to Starboard).
A Relay board is needed to amplify the com port outputs to drive the autopilot Motor
It is a stock Ebay item like this
https://www.ebay.com.au/itm/2-Channe...item4b3e1df0cb
It's tunable with Delays , Gain , Drive Time and PID loop.
I've attached the program zip and manual.
I would like someone with the necessary skills to convert it into an OpenCpn plugin.
The main work needed
1. Decomplile the program (Possibly compiled in Liberty Basic)
2. Allow the use of 38400 Baud (Set to 4800 only)
3. Include activated route to be used as course set point
4. Build as a plugin for easy cross platform use

[ronstory]

Hi-

Interesting, but the ebay link doesn't seem to find item.

[petter5]

A quick google search for the text on he PCB easily find the board:
https://www.alibaba.com/product-deta...522026838.html


/Petter

Originally Posted by ronstory

Hi-

Interesting, but the ebay link doesn't seem to find item.

[petter5]

Price at Amazon UK is £ 5,99


https://www.amazon.co.uk/KKmoon-2-Ch.../dp/B07BQLJRJ7

[ronstory]

Cool! Found it on the US site as well and thanks for the pointer.

https://www.amazon.com/Walmeck-2-Cha...ustomerReviews

[seandepagnier]

It's like saying you want to use seaclear for navigation instead of opencpn.

Don't expect a very efficient autopilot using a windows computer, and nmea sensor inputs. There is going to be a relatively large lag (time from boat turning to rudder reaction) This also going to use a lot of power and be unreliable running on a windows machine.

It would cost about the same to make a much better performing and efficient autopilot using pypilot which already has all the control interfaces implemented and much more.

[ohgary]

Originally Posted by Steelcat

I have been using a windows computer software autopilot that I found.
It only requires a com port , relay board and GPS to operate.
It reads either $GPRMC or $GPVTG Baud 4800 and compares it to the set point then calculates an output that triggers Serial port DTR Pin 4 (steer to Port) or RTS Pin 7 (Steer to Starboard).
A Relay board is needed to amplify the com port outputs to drive the autopilot Motor

Very nice project but I would dump those relays and move to MOSFETS instead.

[rgleason]

As Sean wrote, Pypilot with the appropriate controller and your autopilot motor will save amps and work less.

[skkeith]

I am trying to do all this inside a micro controller. With a modern atmel it is easy to get NMEA from opencpn. Python is a non starter however, can someone refer me to NMEA based autopilot code written in C?

[seandepagnier]

Originally Posted by skkeith

. Python is a non starter

?


Many have attempted all in c with poor results. It is not a very good
Language if you don't want to send most of you time debugging. I have seen half dozen autopilot s like this, all hacks that are difficult to work on and not very efficient use of the motor.

[skkeith]

well there is micro python, but I am attempting to do something light weight low power in a micro controller.