2018-06-14, 04:04 PM
(2018-06-14, 12:54 PM)NahanniV Wrote: I think you are heading in the right direction here, adding a simple "H" bridge, But:The arduino is probably the simplest way to add an ADC to a RPi already.
Would it not be simpler and more efficient to get rid of the Arduino completely and just add an ADC to the RPi ?
There is optical isolation to protect the raspberry and the simplest way to do that is over a uart, not spi.
Furthermore, the raspberry has difficulty generating decent pwm signals especially for 4 channels.
Finally, the arduino can react to overcurrent, end of travel or rudder feedback stops much faster than the raspberry ever could stopping the motor much more quickly.
I got the current down to 16mA for the controller which isn't great. About half of this is the cheap regulator and power LED. Finally, if it were running at 3.3v instead of 5v it would drop significantly. So it's definately possible to make the controller use 5mA or less eventually. It uses about an extra 1.5mA when it's driving the mosfets.
A different uC could probably get the consumption down to 2-3mA
Quote:Come up with a drip proof box with a heat sink and terminal strip for connections and you would have a very simple and easy to install autopilot with better functionality than commercial units that cost thousands of dollars.
The mosfets I am using make it possible to run at 15 amps continous without a heat sink, but 60-80 amps with one.
I tried bolting them to an aluminum case with insulating pads, and insulating washers, and I do not like this. It seems too easy to accidentally short out. I will redesign the board so that the mosfets are clamped a different way.