Sunday 7 July 2024

BlueFlyVario_Audio_v23 released

The new BlueFlyVario_Audio_v23 is the simplest and cheapest Bluefly. It is an audio only vario that is smaller and simpler than bluetooth models, but retains the same settings as its bigger brothers. 

This vario is released in kit form and requires simple soldering of the battery to the circuit board for normal assembly.

What is in the bag?

The BlueFlyVario_Audio_v23 is shipped with:
  • The BlueFlyVario_Audio_v23 circuit board. This is 40mm x 27 mm and is sized to match the battery. 
  • A small piece of neoprene to protect the pressure sensor from light. Note that you should leave the white tape on it as shown in the assembly instruction below. 
  • A 900 mAh LiPo battery. This is the same battery used in the Bluetooth models of the vario. You will end up trimming the connector from the wires and soldering them to the circuit board. 

Hardware Features

The BlueFlyVario_Audio_v23 features:

  • The same sensitive pressure sensor, processor, and audio output of all of the v22 and v23 Blueflys.
  • A USB-C interface (with attached FTDI serial port). This can be used to:
    • Adjusting settings with the BFVDesktop
    • Connect to apps such as XCTrack using a USB OTG cable.
    • Charge the battery (if connected)
    • Power the Bluefly (if no battery is connected) 
  • The same 900mAh battery as its bigger Bluetooth brothers (but with more life as it does not need to power bluetooth).
  • Two buttons:
    • The main button shown in the picture below above the USB-C port. This is used for normal powering on and off. 
    • The slide switch used for isolating the battery. Slide to the right is on. Use this for doing a hard reset, or fully powering down if you are not going to use the vario for months. 

Note that although UART2, UART3, and SPI1 are exposed they are really only for advanced users who want to tinker. 

The RST and GND pads shown in the top left work like other Bluefly models to perform a hardware reset (short them during startup).

Assembly Instructions

These instructions assume you are going to power the BlueFlyVario_Audio_v23 with the included battery. If you instead plan to power from USB directly see the note below. 

Before you start get a feel for how the battery is matched with the board. Generally, I like have the printed side of the battery matched with the board, and run the wires along the board under the top edge of the battery as I think this fits neatest. 

Start by sliding the battery isolator switch to the left so that when you solder the battery it does not start up before you are ready. 

Next, cut the connector from the end of the battery wires. Strip the wires by a few mm, then solder the red wire to V_BAT and the black wire to GND. The secret to good soldering is to use flux, leaded solder, and clean with isopropanol. See the image below for how it should look.
To test it is working slide the battery isolator switch on and the vario should start. Press and hold the main switch for 3 seconds and it will turn off. 

Next, place the battery on the base of the board. I like to secure it with some thin double sided tape to hold it in place. Notice the wires tucked under the end of the board and the neoprene in place to protect the pressure sensor. 
At this point you have a few options for how to enclose the vario. See below for a 3D printed case, blue tape, and clear tape options. 

You can download the files for the 3D printed case from thingverse. To print the case, lid and button your will need to have a 3D printer with pretty good tolerance and some skill using it as the parts are pretty fine. If you design a better case please share it with me. 

A 3D printed case can be pretty tidy, but I actually prefer the simple tape method shown below. The overall size is smaller, and it is easier and quicker to hold everything together (and also easier to remove if you want to modify something). Make sure not to block the sound port of the speaker. 

The primary purpose of the tape is to protect the battery from any physical damage while using the vario. You might like to include an extra layer around all parts of the battery just in case, as a damaged battery can be dangerous. 

Alternate Power Options

You can also power the BlueFlyVario_Audio_v23 using the USB. You should only to this if you intend not to connect the battery. Close the USB PWR solder jumper with a dab of solder. When the USB-C port has power the Bluefly will start. Note that the slide switch has no effect, and also that the number of start-up beeps reflects that the input voltage is above 4.2V.

You could also power the vairo from an alternate source via V_BAT. Voltages from about 3.5V to about 5.5V should work. Below this range will not work, and above this range risks damaging the regulator. 


This is the simplest of Blueflys:
  • Press the main button and the vario will start. 
  • It beeps when you are in lift :)
  • Long press it for 3 seconds and it will shut down. 
  • Connect to the BFVDeskto application to adjust settings, although the defaults work for most pilots.

Tuesday 25 June 2024

More Firmware Updates

Firmware versions M74 and M75

The most recent firmware provides more stability and fixes small bugs. The firmware files are here:
If you look in the folder here here and order by last modified you might find more recent versions of the firmware. 

Firmware update procedures for Bluetooth models

This is the same as the procedure as described in earlier blog posts, but hopefully it is a bit more clear. 

First, you will need a computer which can run windows applications and a USB-A to USB-C cable. You will also need the ds30StudioPro program and the latest BFVDesktop application. Get them here:
Both of these tools need additional software on your PC to work properly (BFVDesktop needs java, and ds30StudioPro needs .NET framework). 

Step 1: Make sure you have your power and connections right

The ds30 bootloader on the Bluefly communicates through the UART1 port of the onboard processor, which is connected to the physical USB port of the Bluefly. So first, we are going to make sure that this is working. 
  • Plug the Bluefly into your computer with a USB cable and make sure to note which COM port is listed in your windows device manager. If this is the first time you have done this it might install the FTDI driver automatically. If not, you might need to install it manually by using the setup executable for the virtual com port driver here
  • Open the BFVDesktop application. Select the COM port the Bluefly is installed as. Then press Connect. Then start the Bluefly. You should see data streaming in from the Bluefly
  • Shutdown the Bluefly by long pressing the clear button. Leave it connected via the USB port. 
  • Ensure that you shutdown the BFVDesktop application before trying to update the firmware - only one application on your computer can connect to the Bluefly at a time.
Step 2: Loading the firmware
  • Note that this will overwrite any hardware settings on the Bluefly and they will be reset to defaults.
  • Open ds30StudioPro. You might need to click 'New' to create a new project. On the Project tab: Select the Device and Bootloader as shown below. Select the Input HEX file application to the firmware *.hex file you have saved on your computer for the model you are updating.
  • On the Communication tab: Set the port to the one which you know from step 1 communicates with the Bluefly, and the baud rate is set at 115200.
  • On the Bootloader tab: Make sure the Write Destination checked as the main flash and not the boot flash.
  • Before pressing the Write button the Bluefly must be shut down (from the last point in Step 1)
  • Press the Write button. 
  • This will start the ds30StudioPro looking for the bootloader on the vario. (If the BFVDesktop application is still running and connected to the then you will get an error as the COM port will be busy)
  • After a few seconds, press the button on the Bluefly to start it.
  • If everything works then the Bluefly green light will come on and the Bluefly will communicate with the ds30StudioPro application (instead of starting normally), the firmware will start writing, and you will have new firmware in the vario in under a minute. You can see the write process with a green bar at the top of the ds30StudioPro application.
  • You might get a communications error because there are some buffers that need flushing in the UART communication pipeline - if so, then shut down the vario and try again and go back to the step where you press the write button. You might need to try this a few times, including unplugging and re-plugging the USB cable into the Bluefly.
  • When the writing is finished the Bluefly should restart within about 10 seconds after some green light flashing.

Step 3: Testing and Settings
  • Before you disconnect everything, open up the BFVDesktop application and connect to the Bluefly again.
  • Look at the firmware version by shutting down and restarting the Bluefly and seeing if the new firmware is on the device
  • Test two way communications by sending some commands or adjusting some settings.
  • If you have the IGC model, you might want to press the IGC button and format the IGC memory.
Firmware updated procedures for TTL models

Follow the firmware update procedures described in this earlier blog post

Saturday 3 February 2024

Minor firmware update M72 and M73

M72 and M73 Firmware Update (v22 and v23 models)

Update 2 Mar 2024: The M72 firmware update for Bluetooth GPS_IGC models had a bug which sometimes made the vairo hang when the bluetooth connection was lost. Please use the most recent M73 firmware update for these models:

This minor firmware update improves the reliability of vario shutdown and reduces the instance of the Bluefly becoming unresponsive. 

The firmware files are here:

Follow the firmware update procedures described in this earlier blog post. I recommend resetting default settings and formatting IGC memory after you have done a firmware update. 

Thursday 28 December 2023

IGC Validation and New Firmware

It has been while since my last update. A few things have been happening behind the scenes. This post announces IGC validation for the Bluefly and describes the latest firmware and software.  

IGC Validation

I am happy to announce that validation of Bluefly XBF signed files is now officially supported by the FAI-CIVL open validation server. Validation for IGC files is required for some competitions, and importantly for many of us is used by XCContest. 

A few years ago some models of the Bluefly got IGC tracklog recording. But until October this year the only way to validate to the file was to download it via GPS Dump as described in this post

For the technically minded, the IGC signing process is handled in the hardware. The IGC file data is stored in onboard NOR Flash memory using a proprietary file format as the $GPGGA and $GNGGA sentences are read from the onboad GPS and processed into B records. The IGC file is signed on the Bluefly using the XBF protocol when recording has stopped (when the Bluefly is shut down).

The Bluefly IGC file can be downloaded using the BFVDesktop application available from using the procedure describe in this post.  Users can connect the Bluefly to a PC and it appears as a serial port. The BFVDesktop application communicates with the Bluefly using commands over the serial port, including commands to list files and download them individually. Users can also format the NOR Flash memory.

The following models include IGC recording. These are all based on the same codebase and use the same IGC format and memory protocol, with the relevant updates to the IGC header to reflect hardware and firmware versions.

  • BlueFlyVario_Bluetooth_GPS_IGC_v23 (current model released May 2023)
  • BlueFlyVario_USB_TTL_GPS_IGC_v22 (current model released May 2022)
  • BlueFlyVario_Bluetooth_GPS_IGC_v22 (previous model released May 2022)
  • BlueFlyVario_Bluetooth_GPS_IGC_v12.3 (previous model released June 2021)
If you want to do validation separately from the open validation server you can download vali-xbf.exe.

M70 Firmware Update (v22 and v23 models)

I have also recently completed testing new firmware for the v22 and v23 models. I only recommend updating firmware if there is a new feature you want to try or if you are not happy with the performance of your vario. 

The key changes are:

  • Updated the $XCTOD sentence used to send voltage and temperature data from the Bluefly to XCTrack
    • Adds a checksum to make it more robust (see here for more explanation). 
    • Fixes a battery voltage error from some firmware versions.
  • Added a new beepDutyCycle hardware setting. You might want to use this to change the nature of the Bluefly beeps, or perhaps to prolong the battery life. 
    • By default when the Bluefly beeps in lift the ratio of beep to silence is 1:1. 
    • It beeps faster when you go up, but still the length of the beep and silence is the same. 
    • By adjusting the beep duty cycle you can shorten the beep to silence ratio. 
    • Start by experimenting with the setting at 0.5 or 0.25.
  • Rebuilt the IGC Flash memory writing code. 
    • For some combination of device and Bluefly there were intermittent errors associated with the periodic writing of track data to the onboard flash memory. 
    • Flash writing tasks now run in the background. 
The firmware files are here:

Follow the firmware update procedures described in this earlier blog post. I recommend resetting default settings and formatting IGC memory after you have done a firmware update. 

BFVDesktop application updated

You can also get the latest BFVDesktop application here: This includes:
  • The new beepDutyCycle setting.
  • An included script for running the application on Mac OS. You should read this knowledge base article for more information. 

Saturday 27 May 2023

BlueFlyVario v23 models released

Today we announce the release of two new Bluefly v23 models. These have actually been shipping for a few weeks now. The BlueFlyVario_Bluetooth_v23 is the latest version of the classic Bluefly. The BlueFlyVario_Bluetooth_GPS_IGC_v23 includes an onboard GPS and IGC tracklog recording. 

The new Bluefly v23 models look the same.

What is new?

These models are an evolution of the v22 models. The main processor is the same and the firmware is almost exactly the same as the v22. Firmware updates will continue to be made for both v22 and v23. 

The main changes are:

  • USB-C charging and serial port interface. The shift from micro-USB to USB-C reflects the standard most devices are adopting, and the physical port is more robust. 
  • The GPS version now uses the L96 GPS module instead of the XA1110. The latter is no longer available and the L96 has better performance, in my experience. 
    • The good news is that the GPS is now entirely inside the case - no more protruding antenna.
    • The downside to this GPS module is that the chip antenna is very sensitive to placement of other components. This was overcome in the v23 model by putting the GPS module on a small board and raising it just a few mm further away from the battery. The end result is a much cleaner layout, albeit that the manufacturing time per device is a bit longer. 
BlueFlyVario_Bleutooth_GPS_IGC_v23 internals, showing GPS module antenna slightly above the base board.
What is in the box?

Both models are shipped fully assembled and ready to use. Simply remove the tape and cover protecting the clear button, press the button and your vario should come to life. Some tips:

Monday 6 February 2023

Firmware Update x68

The latest firmware for all v22 models has been uploaded

Changes include:

  • Fixed a bug with button performance. The button was not as responsive to a press as it should be during lift or sink. 
  • Fixed a bug for GPS models that very occasionally interleaved the PRS and B Record sentence, which might have caused issues for XCTrack users who configured to use external GPS. 

Follow the firmware update procedures described in this earlier blog post

Saturday 8 October 2022

More firmware updates x66

The latest firmware for all v22 models has been uploaded

Changes include:

  • Fixed a significant bug with IGC file recording which was inadvertently introduced in x63 firmware for the models which include IGC memory. If you update to this new x66 firmware make sure to clear your IGC memory by formatting it through the BFVDesktop application.
  • The $XCTOD,Battery%,TempDegC* sentence was added some time ago to improve integration with XCTrack, but I think this is the first time I have documented it. 
    • The sentence is sent from the BlueFly once every ten seconds. 
    • This allows you to add widges in XCTrack for Bluefly battery percent and Bluefly Temperature in Degrees C (as measured by the pressure sensor).
    • See here for how to use this.
  • Minor bug fixes with output text processing. 
  • Little tweaks to improve shutdown performance. 

Follow the firmware update procedures described in this earlier blog post