SK-450 frame with PixHawk PixRacer build continued Spring-2019

I recently found my un-finished SK-450. It was to be my first Pixhawk-class aircraft. I think I will work on it for a while, and hopefully get it more flight-worthy .

Since it's the original PixRacer-clone model in the metal-box/case, I decided to just mount it with four 11mm-square pieces of black HobbyKing Zeal-clone material. I then tied it down with a thin nylon-wire-tie. I don't think a "dental-floss tie-down" is quite enough after all. Like the compass, it would be really bad if the FC became detached in flight somehow.

The on-board RC receiver (a FrSky-X8R) is mounted up-front (upside-down, so that top of X8R still ends-up being accessible) .
If you Bind manually, you want:
Mode-4 (D16) FrSky-XJT = CH1-CH16 with Telemetry. FailSafe-Mode is No-Pulses.

On the Taranis, you can setup a new model for the PixRacer-450.
Actually, I just duplicated an APM ArduCopter model (the Nova-360) , and then changed the name and Receiver Number. I noticed I did not even need to re-Bind. You know they are working (actively bound) when RSSI appears on Taranis. Also, the LED on the x8r will now be lit green.

In May-2019, I'm using the current Mission Planner (for Windows) v1.3.66 . I'm using a standard Micro-USB cable.

Upgraded the PixRacer's firmware from ArduCopter v3.5.4 to ArduCopter v3.6.9 (Quad with ChibiOS). Reboot the PixRacer-FC.

• Click Connect. 
• Reset Parameters with Reset to Defaults button. It will reset to v3.6.9 Defaults. Let it Reboot.
• Save initial default v3.6.9 params to file . Start building-up your best params from here.
• If not already Disconnected in MP, do so now.
• Shut-Down MP, disconnect cable, and power cycle aircraft.

On next power-up, ESC might be beeping.  Seems to indicate that ESCs aren't getting a signal because FC can detect that radio is not calibrated yet (getting that message in MP-HUD). Looks like the constant ESC beeping happens with ArduCopter v3.1.x (or higher) and certain versions of ESCs. And, of course, what the APM-FC considers an un-calibrated RC radio.

• Reconnect USB cable, start MP, and click Connect.
• In MP, set your main top-6 or so Flight Modes and Write/Save them
  1. Stabilize
  2. Loiter
  3. Alt-Hold
  4. Drift
  5. Land
  6. Auto
  ... and in Extended Tuning, CH7=SuperSimple and CH8=RTL (each of which I also have on dedicated Taranis buttons).
   
• In MP, calibrate the RC Radio, 
• The sticks obviously, but since the radio is already programmed, step thru all the pre-programmed Taranis Flight-Modes on the switches. All channels should move on MP screen (except CH6 which is not assigned to anything on Taranis).
• Remember that any problems at this point (like only some switches not responding) might be due to incorrect programming on the Taranis radio itself.
• Write params, click Disconnect and power-cycle (reboot) FC.
• If ESCs were beeping before, they should stop now (now that the radio is calibrated).
• Verify or Set Frame Type to X-Y6A (a X-4 quad-config)
• Recall that you have the PixRacer FC mounted in a normal/forward orientation.
• Compass is Forced-External (which also disables any Auto-Detection). Verify proper Compass Yaw-degrees hardware-config settings. Just using one the single external compass for now.
• I would say these are the minimum parameters you want to set or verify before calibrating:

AHRS_ORIENTATION,0
COMPASS_AUTODEC,1

COMPASS_EXTERNAL,2 

COMPASS_ORIENT,0 

COMPASS_PRIMARY,0
COMPASS_USE,1
COMPASS_USE2,0
COMPASS_USE3,0

FRAME_CLASS,1
FRAME_TYPE,1

Mandatory Hardware Devices - Click Connect and calibrate the rest of the mandatory hardware devices. The PixRacer seems to like being rebooted (and/or power-cycled) after each major component is setup and/or calibrated. Save your work and params files as you go.

If all is going OK with your Micro-USB-cable connection, you should be good to try connecting by WiFi instead. Its your choice.
- WiFi connection notes. Connect to copter's WiFi in Windows first. Use UDP in MissionPlanner .

• Accelerometer calibration. 
• Click the button to do the quick Accel calib (just leave level) and then reboot the PixRacer flight-controller (FC).
• After reconnecting, click the other button to do the longer (multi-step) 3D-Accel calibs. Reboot FC again when finished. 
• Follow directions. I find it easier to prop-up against a door because it must be keep still and perpendicular at each step. Use Enter/Return to go to next step.
• It should say Successful at end. 
• It might show the 6 calibration parameters it just created. IIRC, they should all be close-to or between -1.00 and +2.00. I think it might Write them to the FC at the Successful end.
• You can also see them as INS_??????? in params list.
• Return to Full Parameters List and Write them (just in case). You might need to Connect first. Finally, I Save as a File since we made it this far. 
• Compass Calibration
• Due to initial problems getting more than one compass activated and calibrated (with good Offsets) ... I'm just using the one main external compass (up in the GPS/Compass-Combo module) for now. This should also help with compass "variance errors".
• Calibration is pretty self-explanatory. Just start it and then slowly rotate the multi-rotor aircraft on each of its 3 main axis (likely a couple of times each). If done properly, it should progress and complete in good time. 
• It would not hurt to do this outside (like at least the back-yard). Not only would this eliminate any possible building-structure interference, 
• but also ... you can do it while Auto-Declination and GPS are active. 
• Note that after it has been done successfully, it SHOULD NOT need to be done again, any time soon. 

Optional Hardware Devices - Click Connect and calibrate any optionally-installed hardware devices. The PixRacer seems to like being rebooted (and/or power-cycled) after each major component is setup and/or calibrated. Save your work and params files as you go.

Battery Monitor or Power Module (standard APM-style PM)
- This is with a Turnigy 11.1v 2700mah 3s 20-30c LiPo battery
Monitor: 4: Analog Voltage & Current               Battery Capacity: 2700
Sensor 0:Other
APM Ver: 4:The Cube or Pixhawk
Power Module Calibration
1. Measured Battery Voltage: 11.6v (measure and enter yours here)
3. Voltage Divider: 10.82
6.  Amperes Per Volt: 19.1
For this PixRacer Flight Controller, my relevant parameters were:
BATT_MONITOR,4
BATT_CURR_PIN,3
BATT_VOLT_PIN,2

Reboot, and it should be working and now appearing in HUD.

Also, verify or change these core parameters     
(this first set should also be Pixhawk defaults):

ANGLE_MAX,4500
GPS_HDOP_GOOD,140
LAND_SPEED,50
LOG_BITMASK,176125       (Most logs, including IMU for vibrations )

RTL_ALT,2500
FS_GCS_ENABLE,0
FS_THR_ENABLE,1                (Very important)
FS_THR_VALUE,950              (Adjust for your calibrated radio throttle)

Also DONE :
- Install FAA ID-Tag sticker

ToDo:
- Calibrate ESCs (a good time, since new FC in new aircraft).
- More Arming and motor-run tests.
-     -    Already noticed GPS-Module working really well in shielded areas.
- Calibrate compass again, outside this time.
- Test Fail-Safes and RTL
- Setup Taranis "Flight Time" telemetry Page for this model
- Install props (mark type and direction)
- Tethered flight test.
- Maiden flight
-     -     Stabilize (manual mode) and hopefully some GPS-Modes testing as well.