Tag Archives: hkpilot32

DIY Bluetooth Telemetry Bridge for Pixhawk or APM

I am using my HK Pilot32 (Pixhawk) since last year with my phone and DroidPlanner 2(now Tower). I have tested it as well with one HC-05 Bluetooth module as with 433Mhz Telemetry module. Using it with the Bluetooth module I don’t need to attach anything to my smartphone. But with the 433Mhz I have much better range. How can I get the great range without attaching something to the phone? Idea: using the 433Mhz telemetry module to transmit the data from the Pixhawk to the Bluetooth module and this one to my phone. Well I was not the first one with this idea, and I find a Bluetooth telemetry bridge from Event38. Looks good but the 150$ price is just too much in my opinion. So I decided to stick with my idea and made it by myself.

Parts needed:

Both the HC-05 Bluetooth module and the HM-TRP 433Mhz module work on 3.3V. But to use these with simple small 3.7V LiPo Battery, we need not the bare HC-05 Module. Take the one with integrated voltage regulator and pins already soldered (like the second or third one on the picture below).


If you already have a 433Mhz Kit from 3DRobotics or HobbyKing you need to unsolder the HM-TRP module from the receiver module (the one with the USB Plug). Or as said you can buy only the bare HM-TRP module from Aliexpress. Download the datasheet for the module to check how it looks like and the pins descriptions.

What we need to do:

First both modules should use the same baud rate for communication. The standard for the 3DR Robotics module is 57600. So we need to change the baud rate for the Bluetooth module to be the same. You can check how to do this here.

Then take the 4 tiny cables and solder the pins from the HM-TRP module to the pins of the Bluetooth module as described:

  • 5V HM-TRP Module – 5V Bluetooth Module (before last Pin on the left side)
  • GND HM-TRP Module – GND Bluetooth Module (last Pin on the left side)
  • TX HM-TRP Module – RX Bluetooth Module (2 Pin on the left side)
  • RX HM-TRP Module – TX Bluetooth Module (1 Pin on the left side)


A bit tricky was to solder the antenna to the tiny module. First you need to remove the plastic black cover. Cut the coax cable and remove the PVC shield. Then take the metal shielding and without cutting it, form it as a cable and solder it to the GND Pin of the HM-TRP module. The tiny cable under the shielding layer is the cable for the Antenna. Solder this one to the ANT Pin of the HM-TRP module.

That is all!

I used hot glue to place the HM-TRP 433Mhz module on the backside of the Bluetooth module, so it looks better and its more compact. Now you can connect the pins of the Bluetooth module to the battery and have your own Bluetooth Telemetry Bridge.

Disable the safety switch on Pixhawk

On Pixhawk and all other flight controllers based on the PX4 board (like the HKPilot32x or the AUAV X2) you should press the safety switch button before arming. As this is a safety feature it is recommended that it is enabled. But if for some reason you wish to disable the safety switch function before arming the board, you can do this in Mission Planner.

Open MissionPlanner, connect the Pixhawk and go to the “Config/Tuning”-Tab. Then click on the “Full Parameter List”. On the right side there is a “Find”-button. Click and type safety. You should get this result:


Change the value from “1” to “0” and then click on “Write Params”. That is it. Now you can use your Pixhawk board carefully without the safety switch.

HK Pilot32 – The Pixhawk "clone" arrived

Last week HobbyKing released the HK Pilot32, a controller for Copters, Planes and Rovers, based on the open source project PX4. I mentioned in my last post that I ordered one for me.

Update 21.04.2015: This one looks the same package as the one from HobbyKing, but the price is much better.

And today I received my package from HobbyKing, only 6 days after I made the order 🙂 The shipping time with DHL Express to Germany was just amazing!

Here are some photos from the HK Pilot32 and my first impressions with this flight controller:


On the label you can see that the hardware version is as the Pixhawk from 3DRobotics – PX4 2.4.3.


Overall the quality of the case is good and it doesn’t look cheep. Screws are on top of the case, which is not a bad idea. I miss that there are no holes in the bottom of the case, so I could mount it with screws on my SG Adventure carbon frame. Now I must use the mounting foam.

There are the HKPilot Mega 10s Power Module, Buzzer, Safety switch button, I2C Splitter module, 4GB SD Card (in the HK Pilot32), SD Card reader, Micro USB cable and other tiny cables as well.


I wanted to see the quality of the production, so opened the plastic case by unscrewing the bolts. The solder connections look fine. I don’t know why, but some of the chip labels were slightly erased. Hope these are new, and not used before.


And here one last photo of the case itself. There is some foam on the down size. This is were the barometer on the board is, so you don’t need to do this yourself, as for the Crius or APM board.


Then I connected the board to my computer and the drivers were automatically installed on Windows 7.

Opened Mission Planner, connected the PX4 and there came a message, that a new firmware for the board is available. The HK Pilot32 came preloaded with the open source ArduCopter 3.1.3. The latest stable (not beta) version is at the moment ArduCopter 3.1.5. Downloaded and installed it without a problem, just as on the “original” Pixhawk.

So far everything is fine. Later I will test it on my carbon quadcopter and post how it works. Overall I am very happy going to the next 32bit level 🙂

Update 12.08.2014: Yesterday I replaced my  HK MegaPirate AIO board and FrSky D8R-II Plus receiver with the newly arrived HK Pilot32 and the smaller FrSky D4R-II receiver (It was flashed with the new 27ms CPPM firmware exact as I did it with the D8R-II Plus).

HK MegaPirate AIO = 15 grams; FrSky D8R-II Plus = 13 grams. HK Pilot32 = 33 grams with case; FrSky D4R-II = 5 grams. Overall 10g more of weight.


Connected the motors as shown on the 3DRobotics site and calibrated the ESCs. I also did some small adjustments on my GPS-cable to fit in the HK Pilot32. Calibrating the flight controller and configuring the settings in the Mission Planner was an easy job. What took me a bit more time is to realize, that the new 32bit controller can not be used without the safety switch (Update: Here is how to disable it). With the actual 3.1.5 firmware of ArduCopter if you don’t connect the safety switch, you can arm it, but the motors don’t spin. So Google helped me finding that fact out. Connected the safety switch, hold it for about 3 seconds (until solid red) and then armed the copter. I tested it a bit at home and it was perfect, but the real tests outside are coming 🙂 So here two more photos of my carbon quad before and after.


Pixhawk “clone” by HobbyKing – HK Pilot32

I’m using my HK AIO MegaPirate (Crius clone) board since a few months and I am already very happy with it. The problem with this board is, that I cant get the newest official ArduCopter firmware and I must wait until the developer “SirAlex” port his version of it (MegaPirateNG) to the HK AIO board. The official or clone APM (HKPilot Mega) was not an option. As I saw that the developing of the ArduCopter firmware was going on and on and the APM will not be able to use all the functionality of the coming firmware updates, I decided to go for the PX4 open source board.

This 32bit board is on the market for a half a year thanks to the team of 3DRobotics. You can buy the Pixhawk controller from this page for about 199 $. As I know you get a free support for their products, so if you have problems, you can easily contact their team. That is the benefit buying from them (and the quality of the product… and the case looks very good in my opinion).

But as many people don’t have such amount of money only for the flight controller it becomes a problem. I thought I can order an RTFHawk from witespyquad, but there are big time issues.

And the solution for me came today: Hobbyking has announced their version of the PX4 open source board – HK Pilot32 (I cant name it clone, as the PX4 board is a open source project). The price is about 145 $, for platinum members 136 $ (RTFHawk about 127 $). In my opinion it is fair enough. You don’t get the professional support from 3DRobotics, but save a bit money. I cant say anything about the quality of production until it comes to me, but HobbyKing has never disappointed me so far.

So everyone should decide for himself and most important: you CAN take a decision as there is competition. I ordered mine already 😉

Update 11.08.2014: The HK Pilot32 arrived today. Photos and first impressions here.

Update 15.09.2014: There is also another board based on the PX4 open source project – the AUAV-X2 by Nikolay Arsov. It it smaller and have some nice features compared to the Pixhawk. More in my article about it here (for now only in german, but you can use google translate).