Worked a little on my autopilot today. Making progress. I am 'cipering the right data from NMEA 0183 out from the HDS. Notice I was sitting still and my motor tried to steer me somewhere. I put in a Humminbird donut fix. ha. I had to intercept the SOG (speed over ground) data from the NMEA sentence data and disable the steering motor below .5mph.

My neighbor came over to see what I was doing and was amazed. ha.
It was/is sprinkling rain here, so I couldn't move around to see anything happening.

What you see on the tablet screen scroll is waypoint heading relative to north , "boat" heading relative to north, the difference between the waypoint heading and "boat" heading, SOG and setting the dc level (pwm) to the steering motor.

These are the minimum autopilot requirements of my circuit.