Detect external buses on FMU variants correctly and clean up driver implementation

[dagar]

• merge posix and nuttx Device and CDev
• create px4_i2c_bus_external/px4_spi_bus_external helpers
  • implement special handling for FMUv3 (all i2c external, all spi internal)
• push per driver external checks into Device class

[LorenzMeier]

@dagar I'm currently testing this.

[LorenzMeier]

Compile error:

In file included from /Users/distiller/Firmware/src/drivers/device/device.h:37:
/Users/distiller/Firmware/src/drivers/device/CDev.hpp:110:18: fatal error: 
      'device::CDev::read' hides overloaded virtual function
      [-Woverloaded-virtual]
        virtual ssize_t read(file_t *filep, char *buffer, size_t buflen);
                        ^
/Users/distiller/Firmware/src/drivers/device/Device.hpp:96:14: note: hidden
      overloaded virtual function 'device::Device::read' declared here: type
      mismatch at 1st parameter ('unsigned int' vs 'device::file_t *')
        virtual int     read(unsigned address, void *data, unsigned coun...
                        ^

[LorenzMeier]

I've reviewed the code and ran it successfully on my setup. I have inspected the mag reports from the different mags.

Still needs flight testing but is looking good.

[LorenzMeier]

@PX4TestFlights @mrpollo Please add this to the test queue.

[dagar]

I've verified a few different pixhawk 2.1 configurations with different mags connected to different buses and different board and external mag rotations. Things seem to be correctly marked as external now, but there are still minor issues.

For example the hmc5883 i2c rotation supplied here is not correct for an external device. https://github.com/PX4/Firmware/blob/master/ROMFS/px4fmu_common/init.d/rc.sensors#L77

The original pixhawk 2 cube also needs to be reviewed.

[dagar]

Here's a pixhawk 2.1 cube with current master. The pixhawk is rotated roll 180, and there's an hmc5883 mag connected to the GPS 2 port (aka "internal" i2c).

[LorenzMeier]

Do you feel you can finish rotations and I can focus on just validating them?

[dagar]

Yes, and I think we're nearly done, but one question is how to handle the situation where a rotation is supplied on the command line for an external mag. https://github.com/PX4/Firmware/blob/master/ROMFS/px4fmu_common/init.d/rc.sensors#L77

Should the driver ignore that command line for an external or do we work around it in rc.sensors?

[LorenzMeier]

Just ignore for an external? I'm also fine with working around it for now.

[r0gelion]

@LorenzMeier we don't have a Pixhawk 2.1 to test.

[dagar]

@r0gelion testing other FMUv3 variants would help as well.

[msadowski]

@dagar I just tested this fix with i2c rangefinder (TeraRanger Evo) on Pixhawk 2.1 and couldn't make it work. Are there any extra steps that have to be performed to make it work?

[dagar]

@msadowski can you try the other i2c bus? Please open a new issue if you can't get it working.