Monitor RPM for Gasser?

I’m working with an 800 size gasser, Trad Heli, and would like to be able to infer engine RPM as part of setup/tuning.

Measuring Engine RPM depends somewhat on motor specifics, but knowing Rotor speed would be OK and probably more useful/universal.

Obvious thing to do is knock up an I2C interface to a Hall Effect sensor and place it appropriately.

Would then need to mod APM code to log data, and pass it across MavLink to MissionPlanner
(Which would need to know about it) - which is a fair bit of work.

For me the hardware is easy and the software doable, but a diversion from the main game.

(Line of least resistance is probably to just build a Hall Effect to Analog interface and hijack the Analog channel used for Soanar as a makeshift backchannel, but I’d like to do it properly.)

I’m wondering if anyone is known to be working on this?
(aim is avoiding custom stuff & possible duplication)


Hi Richard, I’ve been dabbling with this concept of a digital tach for the Arducopter for a while. Now that spring flying weather is approaching, I’m going to be trying to get it working. Currently, I’m hoping to get some code working on a Teensy 3.1. I already had some basic code working on an Arduino Pro Mini, but the need for using an FTDI breakout to program is a problem. The Teensy is the same size, way more powerful, and has a micro-USB right on board.

I can figure out how to do the tachometer code no problem. However, I2C interface on Pixhawk is quite a bit more complicated because you have to go through NuttX.

I agree, analog would be fantastically simple, but such a horrible thing to do!!! :slight_smile:

I have been inactive for some time, but I too have a gasser (fitted with an APM 2.5, however) and would like to monitor rotor RPM. I’ve spoken with Rob on this topic some time ago, he gave me the code that he had written. I think it would be best if we had the ability to monitor both rotor and engine RPMs. that way we could identify failure while there is still time to do something about it. Maybe the 3 of us could have a chat sometime and we could discuss the way ahead.

Hi,I am also interested in RPM monitoring.
Now i am working on helicopter autorotation landing control model,it’s necessary for me to input the rpm sensor data to the APM.Now i am using a Graupner digital magnetic RPM sensor to collect the data by HOTT system.
Whether we can connect the sensor directly to the APM?