Sunday 24 November 2013

Android App Updated (version 0.7b)

I just uploaded an updated version of the BlueFlyVario app to Google Play. The update will take a few hours to propagate.

New Hardware Settings

The main new feature is the addition of new hardware settings to work with the new version 7 prototype hardware. You should read this previous blog post to understand how hardware settings work. The new hardware settings for version 7 allow the BlueFlyVario to output pressure and vario data in new ways. This means it is compatible with a wider range of applications via the bluetooth SPP connection. The new settings are:

  • outputMode (default = 0) - Sets the output mode. The available output modes are:
    • 0 - The standard BlueFlyVario output mode. This sends raw pressure measurements in the form: 
      • "PRS XXXXX\n": XXXXX is the raw (unfiltered)pressure measurement in hexadecimal pascals.
    • 1 - The LK8EX1 output mode for use with LK8000. This sends pressure and vario data in the form: 
      • "$LK8EX1,pressure,altitude,vario,temperature,battery,*checksum\r\n": pressure is sent as a decimal integer number of pascals, altitude is not sent (99999 is sent instead), vario is the decimal integer vertical climb rate in cm/s, temperature is in degrees Celsius (1 decimal place), and battery is the battery voltage of the on-board battery (2 decimal places). 
    • 2 - The LXWP0 output mode for use with a range of apps: 
      • "$LXWP0,loger_stored (Y/N), IAS (kph), baroaltitude (m), vario (m/s),,,,,,heading of plane,windcourse (deg),windspeed (kph)*CS": The BlueFlyVario only has a partial implementation of this sentence. It only outputs the baroaltitude and vario (all other fields are blank). Note that baroaltidude is determined from filtered pressure using the outputQNH setting.
    • 3 - The FlyNet protocol:
      • "_PRS XXXXX\n": In this case XXXXX is output as the filtered pressure stream. The filtering parameters used are those from the other hardware settings.  
  • outputFrequency (default = 1). Sets the frequency of output sentences from the BlueFlyVario. The BlueFlyVario hardware runs on a 20ms cycle (50 cycles per second). If outputFrequency is set to 1 then the hardware will send a sentence on each cycle. If set to 2 it will send a sentance every second cycle and so on (if set to 50 is will send a sentence every 50th cycle, i.e. once per second). You might use this with the LK8EX1 output mode to send a sentence five times per second (set to 10). 
  • outputQNH (default = 101325). See outputMode = 2 above. 

You will only see the new hardware settings if you have the new version 7 prototype hardware or have upgraded the firmware on version 6 hardware. Firmware upgrade requires a microchip programmer and the hex file. If you think you can do this yourself contact me and I will send you the hex file (or you can send me your version 6 prototype and I will do it for you).

Other changes

Most other changes to the app are minor such as bug fixes associated with some European locals that use ',' as a decimal separator.

I have added rudimentary support for the new BlueFlyVario_Twin, which has two pressure sensors and can be used to calculate pitot speed and total energy compensated vertical speed. More on that in a future blog post when the new device is ready for release...

Wednesday 20 November 2013

Audio Demonstration Video

A few people have asked me to describe how the audio on the BlueFlyVario sounds. The video below shows this in three parts. It begins with a basic audio demonstration. This is followed by a short demonstration of the sensitivity of the MS5611 and how I use neoprene to protect it from light. It concludes with a bunch of varios beeping in unison.

What collective noun should we use for a bunch of varios? Perhaps a 'bleep' of varios.

Friday 15 November 2013

Prototype version 7 released

Prototype version 7 is ready to order! In fact, I have already shipped about 30 to those that decided to pre-order one in the last three weeks. When I released prototype version 6 almost six months ago I thought I might only make about 50. However, there are now over 200 out in the wild, and each month the number of orders continues to increase. This post will talk about the improved user and design features in the latest release.

User Features

The new BlueFlyVario prototype version 7 is pictured above. The look and feel of the design is very similar to version 6. I have kept the same case and PCB size. The LED locations have moved around a little but I do not think that most users really look at them. You will still need to complete final assembly into the prototype case yourself. See this video:

Other new features include:

  • I have added support in the firmware for outputting different sentences other than the standard BlueFlyVario unfiltered pressure measurements as "PRS XXXXX" 50 times a second. The new output sentences will be enabled with new hardware settings. I will need to update the Android BlueFlyVario app then blog again to describe these new features in detail. As a teaser, the new formats are: 
    • LK8EX1 for compatibility with LK8000 devices which have bluetooth support.
    • A partial implementation of the $LXWP0 sentence (only the baroaltitude and vario fields). You might want to use this to minimize the processor power in XCSoar if you are using the audio on the BlueFlyVario instead of XCSoar. 
    • The FlyNet "_PRS XXXXX" protocol.
  • The audio frequency has been constrained so it can not be set below 130 Hz. In the last prototype the default hardware settings would mean that if you were in strong sink (below about -2.5 m/s), then the audio frequency output would be at about this level or below. The electromagnetic transducer has funky harmonics at about 125 Hz and below, and would start to sound at double or quadruple the set frequency.
  • An updated electromagnetic transducer. It is slightly louder and the one I have chosen has a footprint which is cross compatible with a range of other transducers, which means it is more likely I will be able to continue to source it. I now melt a small hole in the heat shrink so the sound comes out better.
  • I have added a solder jumper near the micro-USB port (which is open by default). If you wanted to remove the battery and power the device directly from the micro-USB port (for advanced users), then you would close this jumper. Essentially, it bypasses all of the charge circuitry. Beware: closing this jumper with the battery connected and then connecting power would destroy the battery (dangerously). 

Design Features

One of my main motivations for prototype version 7 was to design it so it was easier to assemble and test. It took around 30 minutes to assemble and test a version 6 prototype by hand. I have now got that down to 25 minutes for version 7. That might not sound like much, but when I am making them in batches of ten I save around an hour. These efficiency improvements include:

  • An updated PCB layout to make components easier to place by hand. This include aligning 0603 components in the same direction.
  • I have added more copper around the switch pads. This should make the switch more secure. 
  • The battery leads are now connected via 0.1" spaced through hole components. This makes the battery leads neater. Advanced users might also choose to remove the battery and power directly via a two pin header soldered here instead.
  • I got a commercial solder stencil with my last PCB order from This is easier to use than my previous approach of using a DIY stencil etched from a soda can.  
The schematic and PCB layout are shown below. The gerbers or microcontroller code are available for personal use on request, please email me. 

Monday 11 November 2013

BlueFlyVario found

This is a cool story. It is about the BlueFlyVario, but it shows that people are awesome, and that random events can be great.

Stephan was one of the first people who supported the BlueFlyVario vario project by purchasing a version 6 prototype. It was one of the first ten which means he had one with a green pcb. About a month ago he ordered another via the website. I figured he really liked it and was purchasing one for a friend. After I shipped it I forgot to ask him more about it as I got consumed in preparing version 7 (another blog post about that soon).

In the middle of last week I got an email via the website from Balazas in Hungry:
I found a Blue Fly Vario V6 device in Austria near a paragliding area in the bush last Friday while I was there for rock climbing. It was wet, and one of the plastic case is broken, but it works as I tried it. If you can help, I would send back to the owner, probably someone lost it.
It was awesome for Balazas to get in contact with me. In a later email he mentioned that he was motivated by a desire for those that do sports in the mountains to help each other as our sports can be dangerous sometimes. There was more awesomeness to come from him.

I have kept a reasonable record of who I have sent BlueFlyVario's to. I record the last four digits of the MAC address which forms part of the bluetooth name. So I asked Balazas and after his prompt response quickly worked out the vario was the first one I shipped to Stephan back in May. When he found out:
This is amazing, I lost this variometer approx 100m above ground and heard it crashing into the woods. I would not have given a penny that it is still working. I lost it about two weeks ago, so it must have been laying there in the heavy rains of last weeks, unbelievable!
I put these guys in touch with each other and Balazas quickly sent the vario back to Stephan:
A big thank you guys for finding out and sending it back to me. This is really great and a little sensation for me! First of all that someone found it second that it survived the fall from over 100 meters with very little damage and third that it found the way back home via Australia to Austria... 

You can see above the perspex protocase got cracked in the fall. A new one is on the way to Stephan right now. 

I don't recommend dropping your vario from 100m and leaving it for a few weeks in the rain. Even so, it is great to see that even with this punishment the vario still works.  In fact Balazas said when he first picked it up in the forest he turned out on and it beeped, then he paired it. Some people are awesome.