Hola marineros.
I've been researching the sensor input issue , and different possibilities have emerged.
The MPC3008 looks good and has been used a lot with the Rpi already.
I stumbled over Emile Cantin's blog , he uses a ardunio to read sensors, do all math , and send the data in SignalK format!
It looks like it should be easy to do an engine mounted interface for most engines with analogue sensors, sending SignalK data over your preferred bus.
We could even make a code library for the different engine brands, or if someone wants to make some interfaces and sell them , they could.
I think this could help both Openplotter , and the SignalK revolution.
One problem though...
If we use openplotter , replacing original gauges, there's no problem.
If we mount extra sensors , obviously , no problems.
But if we want to get data to openplotter , from original sensors , while keeping the original panel , problems emerge...
First , the original gauges are fed with 12-14,4 volt, 100-300 ohm pull-up's, so the signal voltage goes higher than 3,3 or 5 volt.
Next, In a traditional dual instrumentation , you use senders with half the resistance , as you now have two pull-up resistors in paralell.
So , what I need to do to get this working is to read each sensor's voltage, without affecting it, then scale it down to something the ardunio or Openplotter ADC can read. I guess I'll just have to assume the ref voltage is close to 14,4v most of the time the engine is running.
Any ideas?
Another Rpi project worth checking out is the Homegrown Marine project. Specially his direct LOG input.
Keep up the good work. Openplotter , and the signalK crew, is going to change Boating as we know it!
.manitu
I've been researching the sensor input issue , and different possibilities have emerged.
The MPC3008 looks good and has been used a lot with the Rpi already.
I stumbled over Emile Cantin's blog , he uses a ardunio to read sensors, do all math , and send the data in SignalK format!
It looks like it should be easy to do an engine mounted interface for most engines with analogue sensors, sending SignalK data over your preferred bus.
We could even make a code library for the different engine brands, or if someone wants to make some interfaces and sell them , they could.
I think this could help both Openplotter , and the SignalK revolution.
One problem though...
If we use openplotter , replacing original gauges, there's no problem.
If we mount extra sensors , obviously , no problems.
But if we want to get data to openplotter , from original sensors , while keeping the original panel , problems emerge...
First , the original gauges are fed with 12-14,4 volt, 100-300 ohm pull-up's, so the signal voltage goes higher than 3,3 or 5 volt.
Next, In a traditional dual instrumentation , you use senders with half the resistance , as you now have two pull-up resistors in paralell.
So , what I need to do to get this working is to read each sensor's voltage, without affecting it, then scale it down to something the ardunio or Openplotter ADC can read. I guess I'll just have to assume the ref voltage is close to 14,4v most of the time the engine is running.
Any ideas?
Another Rpi project worth checking out is the Homegrown Marine project. Specially his direct LOG input.
Keep up the good work. Openplotter , and the signalK crew, is going to change Boating as we know it!
.manitu