Improve loop time with new I2C library

[Cyberslug]

Can I suggest that you consider evaluating ESP32_SoftWire as an alternative to the Wire library for IMU communication. This could provide significant performance improvements in the flight control loop times.

While working on Issue #12 I noticed that the IMU readData consumes much of the loop time. As this is an ESP32 based project the ESP32_Softwire project is available as a bit banging replacement for Wire. I was stunned with the performance improvement with loop times reduced by approximately 1/3 in quick tests. Note that I haven't tested this beyond bench test using the DEBUG_LOOP_RATE. Test was conducted with a receiver attached and functioning.

See https://github.com/qqqlab/ESP32_SoftWire (This is by the author of Madflight)

[plainFlight]

Done some testing with settings... plane_full_house with flaps, prop hang and heading hold modes and battery monitor enabled...

In rate mode I get:

Wire loop times:
Peak: 1043us !!!
Av: 978us

SoftWire loop times:
Peak: 829us
Av: 740us

Seems a worthwhile change. I will fly this model with SoftWire enabled to gain confidence. Once flown and happy do you want me to commit to main so you can pull ?

[Cyberslug]

Yes please. I have a little experience with code by the author of Softwire and am pretty confident that it will be fine.

Off topic but since you are modifying the code - I notice that there is a case error in the include statement in SBus.cpp. (Sbus.hpp vs SBus.hpp) I am using platformio on Unix and it causes an error for me. I guess Arduino doesn't complain.

One more trivial one - there is a space missing in the comment on line 227 of IMU.cpp.

I have spent some time improving my development environment so hopefully no more src/... will sneak through.

[plainFlight]

Ok those 2 fixes are in. Hope to fly SoftWire next weekend if it stops raining in UK !!