So I had the opportunity to do my very first SMD solderings. This really seems to be comfortable... I will completely switch to SMD I think.
The I²C to PWM converters work! Here are the features:
- Weight under 1 g
- Works with (most likely many) standard ESCs (currently tested: HK SS 18-20A, ...)
- I²C address selectable via solder jumpers (4 standard mikrokopter addresses dec 82, 84, 86, 88)
- Refresh rate selectable via solder jumpers (417 Hz, 292 Hz, 155 Hz, 49 Hz)
- Pulse width (I²C 0-255): 990µS - 2010µS
- Pulse width at startup (3 s): 920µS
- Motor off when no I²C connection longer than 256ms
- Motor off when microcontroller crashes (veeeery unlikely)
- Powered by the BEC of the ESC, or by an external 5V source (prepared as well)
- Very easy to connect: plug the servo cable of your ESC to the converter, connect the converter to your TriGUIDE via a two-wired I²C cable
- Does also support standard servos
I could test the converters today together with three unmodified Hobbyking SuperSimple 18-20A ESCs (@Dave: thank you very much!!) in flight. These ESCs work with 417Hz (probably like many other ESCs). I couldn't notice any difference in stability or noise or anything compared to my modified I²C-ESCs ("Quax" firmware) or compared to the "Holger-Regler" with my tricopter. Different refresh rates were also tried. 292Hz doesn't feel different to 417Hz; 155Hz is a bit more nervous when flying in the ground effect and doesn't "lock" that well when releasing the sticks after a fast manoeuvre. 50Hz isn't possible without changing the settings of the tricopter. The gain of the gyros has to be decreased about 50%. After adjustment, flying around is possible without problems. But the reactions are generally less precise.
Eagle schematics & layout, source code are available here:
I²C->PWM converter files (updated with jumper description)
I could successfully test the following ESCs on the ground with 417Hz:
Turnigy Plush - 60A, Turnigy Plush - 40A, Turnigy Plush - 25A, Turnigy Plush - 10A, Turnigy Plush - 6A
Second news: My SMD version of the TriGUIDE is finished. I could also test it and it works (phew...!). I added the Eagle files to the existing Eagle zip archive. The software doesn't have to be modified. Weight is 13g.