Sunday 29 May 2022

BlueFlyVario_USB_TTL_GPS_IGC_v22 and BlueFlyVario_TTL_GPS_v22 released

The TTL_GPS model of the Bluefly is designed to add a vario and GPS to a Kobo running xcsoar by soldering it to an internal UART serial port. For technically savvy pilots this has been a popular way to build a powerful and reliable flight instrument. The previous TTL_GPS model was released in late 2021, but the chip crisis has meant that the main processor is no longer available. The new v22 TTL_GPS models use the same PIC32MM processor as the earlier v22 bluetooth models and share most of the same codebase. 

Today I release two v22 TTL_GPS models: a base model BlueFlyVario_TTL_GPS_v22 to replace the v12.2 version released last year, and a new enhanced model BlueFlyVario_USB_TTL_GPS_IGC_v22 which adds a USB interface and onboard IGC memory recording. 

Base Model BlueFlyVario_TTL_GPS_v22 Hardware Design

Most people installing the Bluefly on a Kobo will want this base model. It is cheaper and offers the same functionality as earlier versions. 

The base model TTL_GPS_v22 is functionally very similar to the last v12.2 model. It has the same L96 GPS, shares the same form factor, and primary TTL_GPS pinouts. Most users will connect it to the Kobo via the UART 1 TTL port. Other noteworthy elements of the hardware design are:

  • It uses the new PIC32MM microcontroller as the other v22 models. 
  • There is a new all metal button that is more robust, but still needs to be used carefully. Most users will not use the button as the vario powers on as soon as the TTL port has power from the Kobo. 
  • On the back the RST and GND pads can be shorted while the vario is powered on to reset all settings to default. Make sure to deliberately power it off using the button to save the new settings. 
  • There are a few ways to use V_Backup if you really think you need it, but I do not recommend connecting it or closing the solder jumper unless you have read the L96 datasheet and know what you are doing. 
  • The programming pads are also connected to UART 2, which caries the serial communication from the microcontroller to the GPS. 
  • The UART 3 pads on the back provide another TTL input/output like UART1. If I release firmware updates you will need to interface with these to update the firmware.
  • There are quite a few components not populated as the USB_TTL_GPS_IGC uses the same board.  

Enhanced Model BlueFlyVario_USB_TTL_GPS_IGC_v22 Hardware Design

There are a few reasons why you might want the enhanced model:

  • The addition of onboard IGC recording means that you can record a signed IGC file while the vario is connected to your Kobo. You might use this for a backup, or even as your primary file. This is able to be downloaded via the USB port using the BFVDesktop application or GPSDump. Read earlier blog posts about the Bluetooth models to understand how IGC recording works on the Bluefly.
  • Some pilots might want to connect the Bluefly via the USB port to a windows or android device running xcsoar or xctrack. You can close the USB PWR header to enable the vario to be powered from the USB port. 
    • However, warning: If you close this header and power the Bluefly from the USB-C interface while the Bluefly is connected to the Kobo, but the Kobo is powered down, then you will fry either the Kobo or the Bluefly. I recommend only closing this header if you do not intend to connect the Bluefly to a Kobo. 
    • It is ok to have your Bluefly connected to and powered from the Kobo via UART 1, and then plug in a USB cable to the USB-C interface on the Bluefly (but with USB PWR not closed) This will allow you to transfer data from the Bluefly via the USB-C interface (adjusting the settings, downloading IGC files, updating firmware). 
  • Some pilots might want to use this model connected via a USB cable to an external battery to use as a stand alone vario without a display. You could solder a switch across USB_PWR. 

Like the base model, most users will connect it to a Kobo via the UART 1 TTL port. Other noteworthy elements of the hardware design are:

  • The USB-C interface connected to UART 3 mirrors UART 1. 
  • The USB power connection to V-Backup is only for advanced users that know how the L96 V_Backup works. 

Firmware changes

The firmware builds on the earlier v22 models. It is functionally very similar to earlier versions. 

What is in the bag

The bag for both models contains only vario module, a small piece of neoprene, and some heatshrink to hold the neoprene in place. 

You will need to add your own wires and enclosure (if you want one).


See the assembly instructions for the previous version

Wednesday 4 May 2022

BlueFlyVario_Bluetooth_GPS_IGC_v22 released

This short post releases the BlueFlyVario_Bluetooth_GPS_IGC_v22. A few weeks ago I released the Bluetooth_USB_v22 model and indicated that the version with GPS_IGC was coming. It has been ready to go for a few weeks and I have already begun shipping it to replace the previous GPS_IGC_v12.3 model. 

This new BlueFlyVario_Bluetooth_GPS_IGC_v22 model provides a bluetooth connection to work with an app on your device, and also includes an onboard GPS for onboard IGC recording. For most pilots that will be XCTrack on Android, or Flyskyhy on iOS. The USB connector is used for charging or to provide a USB serial port connection to adjust hardware settings or download IGC files. The addition of an onboard GPS allows XCTrack to be used on Android devices which do not have their own GPS, such as some Android eReaders. 

Hardware changes

The circuit board is the same as the Bluetooth_USB_v22 model. When I released that model I indicated that there were some pads which are not populated with components. This new Bluetooth_GPS_IGC_v22 model populates the GPS and flash memory components, and incorporates new firmware. On the outside it looks exactly the same as the previous GPS_IGC model. 

The changes since the earlier GPS_IGC_v12.3 model are similar to what was described for the Bluetooth_USB_v22 model, such as a better processor and different power scheme. The GPS and memory chip are the same as the previous GPS_IGC. 

Firmware changes

The firmware builds on the Bluetooth_USB model, and adds the functions required to record the GPS data and store it in memory. It is functionally very similar to the previous GPS_IGC model. 

What is in the box

The box contains only the assembled vario, with some packaging to keep everything in place and to avoid the button being turned on. This model is shipped fully assembled by default.

Unboxing and first use

When your vario arrives, do this:

  1. Remove it from the packaging. 
  2. Remove the packaging and tape protecting the button from being turned on in transit. The low profile clear button is difficult to turn on accidently in normal use. 
  3. Short press the button. You should hear the vario turn on. See here for an explanation of the beeps and lights:
  4. Plug in microUSB cable to a charger or a computer. The red light indicates charging. 
  5. Connect it to your Android ( or iOS device ( The blue light indicates the bluetooth connection (double flash every 1 second or so).
  6. After some time the orange light will flash every second, indicating you have a GPS fix (provided you are somewhere where the antenna can pick up signals). 
  7. Connect to the BFVDesktop application via USB to adjust the settings or download IGC files. 
  8. You might instead want to connect to GPSDump to download IGC files, if you need them to be signed. 
  9. You might want to add some velcro to secure it to your flight deck or a lanyard (