I honestly admit, that my 6″ quad (codename GPS Racer) was never very pretty. It was just ugly with that GPS tower on the front. Today it got even uglier: I’ve equipped it with HC-SR04 sonar connected via I2C bus (ATtiny85 to the rescue).
Why, you might ask, have I done something so useless? Answer is simple: to make it less useless. There are at least few problems with sonar and modern flight controllers. First of all, most new boards does not have connections for it. Second of all, it does not work reliably.
It just don’t. It was no unreliable that INAV, for example, disabled it for some time completely. Right now it is back, but used only during landing on multirotors. No terrain following or anything like that. Continue reading GPS Racer: worklog #8 – sonar test platform