The ground station

Today is a good day. I got an idea a few weeks ago looking at ready made ground stations such as this!
  However, my shoe string budget does not cover the $180 needed to acquire the selected product.









I therefore thought of the idea to make one by my self using the FPV parts I recently purchased. It's not an 8 inch monitor, but a 7 inch and it's not as pretty as the ready made ground station. I first bought this aluminum "service case" from Clas Ohlsson, a common utility store in Sweden.

It's fairly cheap and cost only about $31.








I removed the lid tool hanger, I might do something else with it later but for now its gone. My father in law helped me with some intricate drilling to get it all to fit nicely. And this what it looked like. Notice the antenna in the upper left corner.

Here is the finished product with the 7 inch monitor and radio mounted. It can even fit the radio transmitter, batteries and other gadgets that are good to bring for a nice flight.

 

Stuff has arrived!

The things I recently ordered arrived today. Transport took 17 days, which is longer than normal.

 

This picture is supposed to illustrate how I'd connect the items. From top, transmitter and camera. Then LCD display connected to the receiver with the option to use the USB connector instead.

See anything missing? Yes, nothing to connect the camera and the transmitter.. I've apparently forgotten to order a cable, which I thought to be included. On other sites where I've observed the same camera, this specific cable has always been included. However not at banggood. 

This is the missing cable. It connects the USB output to a video cable, which then connect to the radio transmitter.Only $3 and now I have to wait another few weeks to get it.

Stay tuned!

A new era, a new beginning

It's been a while since my last post. The main cause is that I felt the energy drain as the fall gets more visible with worse weather, not too encouraging for quad flights. The darkness is also upon us, which makes flight difficult if it's not during day time.

As I've previously written, I ordered the radio telemetry, which I now got working. No hassle, it worked instantly. The only fault I did was to not turn down the COM-port speed from 115k to 57k, there after it worked as a charm :). The picture displays how the flight controller is connected to the laptop and Mission Planner using the radios. The radios are basically a wireless serial port.

 

Next, I focused on the darkness or rather how to fly when it's not full day light. Dusk has previously also been a hassle but these lights should mitigate that obstacle. Looking close at the picture below you can see how I wired the break out wire directly to the power distribution board. The board has tiny connectors all over, which allows soldering and therefore can provide extra connectivity as these lights require 11V.

 

Now to the final product, I started putting the quad back together, putting the lights in place. Hope this can light up any future winter flights.

I decided to go with green on the front and red on the back. Traditionally you should have green to the left and red to the right, but that doesn't help me when I usually see the quad from behind. Therefore I went with red to back and green up front.

 

Whats broken

 

Today's casualties:

• Bottom right boom was bent
• Propellers spent as you can see
• One motor with strange sounds
• Ultrasonic range finder is MIA
• Few nuts and buts are spent

I found all electronics including flight controller, GPS, radio and ESC's to seem to work as usual.

Next thing I'll buy is the telemetry radio :).

Shoestring FPV kit

Something I haven't written about yet is FPV on a shoestring budget. The main reason why I haven't is that I can't currently afford it. However, here is a suggestion that definitely goes on my wishlist for Christmas.

First item on the board is a camera. I've previously written about the key chain 808 DVR for less than $7 that does OK recording. But for FPV you need something else. Now there is a version 2 of the 808 key chain camera that can do just that. The kit also includes a USB to video out cable that can be attached to any video transmitter to enable FPV. The improved camera is fitted with a 120 degree wide angle lens instead of the crappy narrow angle lens on the cheaper 808. This camera goes for $39 at eletoponline365's eBay shop.



For transmitter, I'd choose something with a low frequency again as with the controller radio. That is to gain as long range as possible. I found this kit at Banggood featuring a 1.2GHz transmitter. Other FPV kits regularly feature 5.8GHz. The problem with 5.8GHz is that you need clear sight between the transmitter and receiver. With a 1.2GHz it can work with some obstacles. This transmitter and receiver kit goes for $56 at Banggood.





A OSD device is something some people prefer as it applies a virtual head up display on the FPV image. The OSD device is hooked between the camera and radio transmitter hijacking the image and applying OSD using data from the flight controller. An OSD usually applies information such as: virtual horizon, altitude, air speed, heading, direction and range to "home". Home as applied for RTL. This OSD goes for $27 at Banggood.

You probably need additional wiring to connect the kit together but these are the basic devices needed for FPV.

Summarizing purcuses:

• $39 - 808 #16 v2 key chain camera
• $56 - FPV radio
• $27 - OSD device

In total, $122.

One motor down..

Yesterday, I started trimming the AltHold function that relies on any altitude sensors. The sensor I have so far been using is the barometer, which is very noisy. That means it's less then perfect at holding it's altitude, but works +/- 1-2 meters.

Today, I thought of doing some more testing, maybe even try the AutoLand function as the AltHold seemed to work. However, after a few minutes of flying this happened..

 

One of the motors came off upon takeoff and took a piece of the radio antenna with it. The motors are fastened with two screws at the bottom and it seems as it came unscrewed, possibly due to vibrations. This seem to be the case for one other of the motors when I checked them all. It seems as checking the screws before going flying is a bullet on the pre-flight checklist.

Now, I only found one of the screws, which means, I have to get another somehow. Not sure if I should order a whole new frame as spare part or if I should try to find one in a local utility store. I'm going to try the second option tomorrow to see if they have any thing available that would work as a substitute.

Yes, there will be more videos. I have two that I filmed yesterday when doing some trimming but I haven't uploaded them to YouTube yet as my bandwidth is limited and the amount is not unlimited at the moment.

No success without a little ooops!

Progress! I've got both radio modules talking to each other after flashing with the openLRSng firmware. I actually didn't do any changes to the default settings and it compiled without any issues. The upload of the firmware however was a bit complicated.

As I mentioned in a previous blog post, I bought a USB serial converter called CP2102. What I probably should have bought was a FTDI adapter. This adapter has a pin called DST, which is needed to auto reset the target board when the new firmware has been transferred. The CP2102 however does not provide easy access to the DST pin. The solution was, as many others have done is to do a make shift soldering on the USB adapter in order to provide access to the DST.


And, first off, I cannot take credits for this tiny soldering. It's been done by a another guy who is far better than me. The solution consists basically of connecting pin 28 from the chip in the middle to output on the RST pin. A resistor was also removed to break the RST connection to not get double signals. I actually removed the resistor and made the other soldering, which probably was way easier. Soldering the wire to the 28th pin of the chip had to be done under a microscope :).



So, now we've got a working radio link that I've verified to provide signals that work as intended. The picture below shows how I've connected the radio receiver to the power distribution board, which also connects to one of the ESC's that connects to one of the motors. I'm now in the process of programming and calibrating the ESC's. This is needed to ensure that all motors behave in the same way and provide the correct amount of power given the throttle.

Todays ooops! happened when I by accident short circuited the battery and left some ugly marks. I should have put shrink tube on the soldered connectors of the power distribution board before playing with it, but I didn't :[.

Fixing up the power distribution board

Today was a day of soldering. Two tasks had to be performed to make the power distribution board work as intended. First off, it's connectors were incompatible with the connectors of the battery pack. That was solved by cutting away the TX60 connector and soldering a pair of 5.5mm gold connectors instead.

You can spot the old yellow TX60 connector up in the top right corner of the picture. New connectors were soldered after some trouble with the thicker soldering tin I bought today. I bought 2mm soldering tin, which turned out to be a pain to use as it took quite a bit of heat to melt. I ended up using thinner soldering tin instead.

Thereafter, I soldered the uBEC current converter onto the auxiliary power connectors on the power distribution board. The uBEC is intended to connect the power distribution board to the flight controller. As of the specification, the flight controller may switch anything from 5 to 12v but forum posts recommend using an external uBEC instead as overheating then only destroys the uBEC and not the entire flight controller.

The picture above shows the uBEC soldered to the power distribution board's aux connectors as well as the new 5.5mm gold connectors.

I've also soldered another ESC today with the same amount of success as the last one. Think I'll do another one tonight. Next question is, how do I bring voltage to the radio receiver? Not figured that one yet, stay tuned.

Using 433MHz or not?

I just got a tip from somebody I meet that using 433MHz for radio controlled models might not be such a good idea. The 433MHz band is free for usage but is also being heavily used by amateur radio enthusiasts. I was however suggested to use 439MHz instead as that frequency apparently is reserved for RC usage.

I'll be using the OrangeRX radio, which is open source and as far as I understand can be tuned for different frequencies by simply changing the code. I'll try that when the items arrive :).

Link to OrangeRX OpenLRSng: https://github.com/kh4/openLRSng

Schematic drawing

This is the way that I see that my quad will be hooked up. As I'm new at this, I will keep this drawing up to date as well over time.

The radio

Choices, choices. Changes, changes.. I realised that the Turnigy 9X radio that I've chosen was in back order. I therefore made some changes. The radio that was available however was the same equipment but without its radio transmitter. I then browsed various choices of radios and stuck with a OrangeRX 433MHz radio module.

The main difference between the regular 2.4GHz radio and an 433MHz is that the lower frequency radio has longer range. A 2.4GHz radio may have a range of 300 meters open space, where a 433MHz radio can reach much further and does not require open space.

I also ordered a Bluetooth hardware to connect to the flight controller. This means that it will be possible to control the quad from my android mobile ;). Point and click on a map and it will go there.

Last but not least, shopping list is updated located in my first blog post.

Have a good weekend!