Monday 5 April 2021

BlueFlyVario_Bluetooth_USB_v12.3 released

The BlueFlyVario_Bluetooth_USB_v12.3 is another minor update to the previous version released a few years ago - the Bluefly has a new button! 

Please read this post in conjunction with the release post for the BlueFlyVario_Bluetooth_USB_v12 and the release post for the BlueFlyVario_Bluetooth_USB_v12.2 to understand the changes.

The new button

One of the most frustrating part of electronic design is getting the physical user interface right - the case, usb connector, lights, and button. I have experimented with a few different buttons in the Bluefly project. The trick is to find the right balance between usability (including with gloves), avoiding accidental presses, cost, reliability of component supply and appearance. The button on previous versions met most of these requirements, however some pilots found that it was pressed accidently too often. 

The new button is a lower profile 4x4x1.5mm smd tact switch that is actuated with a machined acrylic part. The button hole in the translucent blue case is machined to 6mm diameter to fit. It costs a bit more, and I need to machine the acrylic myself, but I have found it to be much more pleasant to use. It was tested with competition pilots earlier this year and I am now happy to release it as the default Bluefly button. 

For those pilots that have followed the Bluefly journey since the beginning, the clear acrylic button might make you think fondly of the first sandwich case released with version 0.5b

What is in the bag?

For self assembly, the v12.3 model of the BlueFly is supplied with the following components:
  • The BlueFlyVario_Bluetooth_USB_v12 mainboard. There is a small piece of neoprene covering the pressure sensor; glued at one end to hold it in place (do not remove it)
  • The translucent blue case with four small screws (P1 screwdriver needed) and the machined acrylic button.
  • A 750 mAh single cell Lithium Polymer battery.


Assembly is pretty simple and will take most people less than 5 minutes. However, if you would prefer not to touch a screwdriver, you can order the vario fully assembled.

Step 1 - Initial Test

Before you put the board in the case, plug in the battery, press the button, and make sure you can hear the vario beep. Also, plug in a microUSB charging cable and make sure the red LED comes on.

Step 2 - Fit the button into the case

The button should fit neatly into the case as shown in the image below. The machining looks a bit rough under the magnifying glass, but is neat at the surface that matters. You might feel the need to scrape of machine fragments of the case or button with your finger nail. Make sure the button can move easily in the hole. 

Step 3 - Screw the board into the case 

Place the board in the case ensuring that the USB connector is in the hole at the end. The USB edge of the PCB should be flush with the inside edge of the case. 

The small self tapping M2.5x5mm P1 screws secure the board into the case. You really only need two screws on a diagonal, but there is no harm if your use all four. Don't drive the screws home to tightly or you will strip the stand-offs in the case. Just use enough pressure to ensure that the board is secure.

Step 4 - Battery and close

Plug in the battery and place it on the back of the PCB centrally between all four screws, making sure not to place it on the end of the screws. Then close the case. 

Step 5 - Check charging works

Plug in a microUSB cable to charge the vario. The red light should come on. Cables with longer tongues work better.  

Step 6 - Velcro and/or lanyard (optional)

Many pilots will put a small piece of velcro on the back of the vario to attach it to their flight deck (this is what I do). Others will drill some small holes in the case and attach a lanyard (I do not do this anymore). 

Next Steps

After install you probably want to connect to the BFVDesktop application to adjust settings, or connect to and Android or iOS device to experiment with different apps. See the software page for more information.