Speed-Data directly from Sensor

[michael.trilling@gmail.com]

Hi gypsylon,

Yes, you can read seatalk 9-bit with the arduino mega. That works, but than you have to write a sketch to transform it to nmea. I have none, so you have to write your own.

You idea of reading the pulses of the speed sensor directly with the raspberry pi might work. But as you noticed, you will need optoisolation and - again - some piece of script that translates it into nmea. Here too, I have no such script and you have to develop you own.

So - the easiest way is to rrad the pulses of the speed sensor with an arduino and use the sketch of Mike Holden (see link above) to translate them to nmea.
No hassle with optoisolation and a ready to use piece of software.
For reducing the 12V of the sensor to readable 3.3-5.2V your pull down resistor should work.

If you run into any probs, just send me a pm. Should be easy to copy my running solution to your environment.....