Sunday, 7 June 2015

TTL_GPS Support Tips

The TTL_GPS model of the BlueFlyVario and a Kobo eReader can be the basis of a great vario in the hands of a reasonably experienced electronics tinkerer. Some people find it a little difficult to install successfully. This post provides a few tips.

Easy Install Method

There are many ways to install the BlueFlyVario_TTL_GPS to a Kobo. My current favorite install method involves using the included connector so that the vario is removable from the Kobo for easily adjusting Hardware Settings or doing firmware upgrades. If you are just experimenting with using a Kobo as a vario, or you are a little unsure what you are doing, then I recommend using this simple install (see the release blog post for more information). Advanced users can always install in a more robust way by de-soldering and re-soldering later. A few tips:
  • Install the right angled pins flush with the board. This makes the BlueFly sit flush to the front of the Kobo. The image below shows the sequence of pushing the plastic on the pins, cutting the pins, soldering, then removing the plastic from the pins.
  • Use the neoprene (essential) and heatshrink (not shown in the image below) to enclose the BlueFly, then fix to the front of the Kobo with double sided tape. Leave the covering on the sticky side of the neoprene and use the black squishy side to cover the pressure sensor (the sticky glue would block the holes). 

Using a USB to TTL Serial converter

A USB to TTL Serial converter makes it much easier to adjust hardware settings and is essential if you want to do firmware upgrades for the TTL_GPS model. You can adjust hardware settings when the BlueFly is connected to the Kobo with Putty and Telnet (see this blog post), but is is much easier with a USB to TTL Serial converter and the BFV Desktop application. The converter I use is shown in the image below. These can be purchased from eBay for a few dollars. Search eBay for "usb ttl serial". I only use the FTDI based converters as I am super confident that the drivers are kept up to date for most platforms.

Once the converter is plugged in to a Windows computer it should install as a serial port automatically. Have a look at the website of the converter chip manufacturer for appropriate drivers if it did not install. Take a note of what the serial port is. Depending on your version of Windows you might need to look in your device settings.

The connection between the converter and the BlueFlyVario_TTL_GPS is shown below. This converter is set to provide 5V of power. Note that the TTL levels on Rx and Tx are therefore 5V which is out of spec for the BlueFlyVario's 3.3V micro-controller, but I have not found it to be an issue with the 2.2k resistors in series. If the converter is set to provide 3.3V the BlueFly draws enough current on start-up to reset the converter, which is annoying. The most important thing to remember when connecting the BlueFly to the Converter is to ensure connections as follows; 
  • GND (BlueFly) to GND (Converter)
  • Tx (BlueFly) to Rx (Converter) 
  • Rx (BlueFly) to Tx (Converter)
  • V+ (BlueFly) to V+ (Converter)

With the converter plugged in with a USB cable run the BFV Desktop app (get the latest version from the support page). Next, connect to the relevant converter serial port at 57600 baud. Turn on the BlueFly by pressing the button and you should see data from the BlueFly streaming in. Using the BFV Desktop application you can then easily adjust all hardware settings. See the hardware settings manual (also on the support page) for information on the range of hardware settings.

If you want to update the firmware then I suggest ensuring communication with the BlueFly via the BFV Desktop app first. That ensures you have an working serial port connection. See the support page for information about updating firmware and how to use the DS30loader application. Note that you can only connect the BlueFly to one application at a time.

Debugging GPS Performance

The performance of the PA6H GPS is different the GPS in your Smartphone. It has no connection to the internet and often takes longer to receive satellites. Also, the antenna is generally not as good. Nevertheless, when it is working well most uses find it more than good enough to support flying. The most common questions I get about GPS performance ranges from the message "GPS Not Connected" to poor altitude performance.

The first step is to check if GPS messages are being sent to xcsoar. Check this in xcsoar by looking at the data stream coming in the Monitor (Menu|Config|Config2/3|Devices|Monitor). Check if the GPS messages are being sent to the vario. If the GPS LED flashing (it is either blue or red), then messages beginning with $GP... should be sent to xcsoar (GPS Data). A few are sent every second. If you can't see any messages then the BlueFly might not be connected properly, the xcsoar device settings might not be correct, the BlueFly hardware settings might be wrong, or there could be a hardware problem.

If you have GPS messages and are still having problems then check the HDOP and VDOP values in the $GPGSA messages. See this page for a description of these sentences. To enable detailed analysis set up the NMEA logger (Menu|Config|Config2/3|System|Setup|Logger|NMEA logger = On), record a track, then download the log to the PC using the Kobo in Nickel mode. If the HDOP and VDOP look good then the GPS should be giving a good fix.

For some earlier versions of the BlueFlyVario_TTL_GPS firmware it is possible $GPGGA sentences were clipped when you get a DGPS fix. If the messages are clipped (one character in the checksum instead of two) then update to the latest BlueFly firmware.

Lastly, note that the GPS vs Vario altitude in xcsoar is sometimes messed up. This article by Neil Page describes the various altitude settings. Use barometric altitude in preference to GPS altitude.

If these tips did not help then the best way to ask for support is to email me using the contact section of the website

Friday, 15 May 2015

Updated BlueFlyVario_Bluetooth_v10 Assembly

I released the BlueFlyVario_Bluetooth_v10 about six months ago (see this post). Most pilots have had no trouble with assembly, but there have been a few issues for some and there is always room to improve. This post describes a slightly different mix of parts you will receive and a simplified assembly procedure. Also, I have made a video of the assembly in response to quite a few requests.

What has changed and why?

  • The PCB is now shipped with the heatshrink and neoprene on. This part of the assembly was tricky for some pilots, the heatshrink would get all messed up, or the neoprene would be stuck the wrong way. I previously suggested putting the battery under the heatshink, now I am advocating to put it outside the heatshrink on the underside of the PCB. This idea came from a Red Bull x-alps competition pilot who wanted to be able to change batteries more easily. 
  • The screws and standoffs are now black plastic instead of metal. There are many good things (5g less mass, greater bluetooth antenna range), but I think it just looks cooler. 
  • The hole for the button on the blue translucent prototype case is now laser cut when the sides are made. This is neater and easier than having to drill every one. 

What is in the bag?

The components in the package are:
  • A BlueFlyVario_Bluetooth_v10 module with heatshrink and neoprene on. This has been bench tested.
  • A translucent blue acrylic prototype case. The acrylic is covered in brown paper.
  • Black nylon screws and standoffs for the case; four each of 12mm screws, 6mm screws, 5mm standoffs, and 6mm standoffs. You will need to shorten the 6mm screws by about 0.5mm using a sharp knife.
  • A 600mAh battery with 1.25mm 2 pin molex connector. The battery has some double sided tape on one side.

Follow the instructions in the video. The testing procedure is described in more detail in the post about the initial release (I did not follow it closely in the video). Please contact me if you have any questions or suggestions.


Sunday, 3 May 2015

Using an external speaker

On the version 10 models of the Bluefly there is a header to connect an external speaker. I have not used it much but have received a few questions. Unless you a really into electronics hacking I would not recommend using a different speaker.

Standard layout

The standard speaker on board the version 10 models is one of the following:

These are all 15 ohm to 20 ohm electromagnetic speakers. On the Bluefly the speaker is driven by a square wave switching a transistor. The circuit diagram and pcb layout on each of the model release blog posts shows how it works. 
The Bluefly runs on 3.0V (TTL_GPS) or 3.3V(Bluetooth and USB). When the transistor is 'on' the speaker would consume up to 150 to 220 mA, however when sounding it is driven by a square wave and making a continuous sound only consumes up to 70 mA. The regulator can provide 100 mA so we are near the limit of its performance. 

Using a different speaker

If you want to use a different speaker a 16 ohm (or greater) device rated for 3V should be used. You could connect it directly to the output, but a connection with a potentiometer is probably more appropriate so you can do some manual volume control (let Google be your friend to see how to wire a pot to provide volume control - search "potentiometer speaker volume control"). I can't recommend a particular speaker, other than advising that larger size generally equals greater sound volume. 

It is prudent to disconnect the current speaker or else it will be in parallel to the new one, and therefore decrease the overall resistance of the speakers. It is tricky to remove the surface mount speaker. The simplest thing to do to disconnect it is to cut the trace to the negative speaker terminal. Only two of the four pads are connected. The positive pad is connected directly to Vdd. The negative pad has a trace (either on the top or bottom) which can be cut. See the board layouts on the links above. Cutting the trace is obviously a one way thing, which is why it is only for serious electronics hackers.

[Edit: The image below shows the speaker pin holes on the BlueFlyVario_TTL_GPS_v10(rev2) board, and the location of the track on the underside of the board which leads to the negative terminal that you would need to cut to isolate the existing SMD speaker.]

Sunday, 22 March 2015

BlueFlyVario_TTL_GPS_v10 improvements

It has been a long time in between blog posts (almost 11 weeks)! This little hobby continues to keep me too busy. It has been one of the worst flying seasons in Canberra for many years which has given me time to continue production, build weather stations (the freeflightwx), and work on the BlueFlyVario.

I have been working on some new devices. In a future post I will describe plans for a BlueFly model that includes Blutooth, GPS, an SDCard for recording tracks, and USB computer interface. However, this post is all about improvements to the TTL_GPS model to make the GPS work better.

The issues

A few pilots reported that the BlueFlyVario_TTL_GPS with Kobo/xcSoar combination occasionally dropped portions of the track or had difficulty maintaining a satellite fix. With the help of our community of pilots I have determined that there are two distinct issues, both of which have now been addressed.

The first issues is a simple firmware error. In the firmware version M01 to M04 the GPS sentences being sent from the PA6H GPS were being clipped if the sentence length was longer than 79 characters. A NMEA sentence can be up to 80 visible characters long. Unfortunately, the bug clipped the sentence when it was longer than 79 characters, meaning the GPS data was not being transferred through to the Kobo. There are only some very particular circumstances when the PA6H would use the full 80 characters. The PA6H needs a DGPS fix (which we do not get in Australia) and needed to fix 10 or more satellites. In strong signal areas of Europe this can happen, and was causing dropouts which were very difficult to understand. The fix was super simple and has been rolled into the M05 firmware release (which will be on the support page of the website shortly). Unless you are having issues with a bad GPS track, and the NMEA log shows you are getting dropouts, then I would not worry about upgrading the firmware.

The second issue is associated with power supply noise and the ability of the GPS to get a good fix. I postulated that there are a few causes of the GPS power supply noise:
  • Broadband power supply noise from the 3.3v UART power from the Kobo. I measure that as around 70 to 100 mV pp (measured on an oscilloscope with AC coupling, 1x probe)
  • Broadband power supply EM emissions from the Kobo which are picked up by wires or the BlueFly/GPS circuitry. 
  • EM emissions from the Kobo which are at GPS frequencies (or appropriate multiples) and increase the baseline a real GPS signal must overcome. 
1 and 2 combine to affect GPS power supply noise on the BlueFly module. In the rev2 board on the first realease of the v10 the noise was filtered with only a 0.1uf cap at the input to the GPS, but further upstream the TC1015 regulator has 1uf on both the supply and output. This gets the Vpp down to less than the PA6H spec requirements of 50mV pp.

Improving power supply noise on the rev 2

If you have a BlueFlyVario_TTL_GPS_v10 with a rev2 board then you can adopt the following strategies to reduce power supply noise:
  • Make sure the wires which connect the BlueFly module to the Kobo are as short as possible, less than 5cm if possible. 
  • If the wires are longer, include a twist in the VCC/GND pair and the Tx/Rx pair.
  • Make sure that the wires are not routed across the middle of the Kobo PCB. 
  • Make sure that all solder joints are clean of flux. A little acetone on a small cotton swab will help clean any connections you have made. 
  • While the VBACKUP can improve time to first fix when you first turn it on, the long wire can also pick up electrical noise so you should consider if it is really needed. 
Further improvements - The rev 3 pcb

To further reduce power supply noise we needed a new pcb layout and some extra filtering components. The latest batch of BlueFlyVario_TTL_GPS_v10 pcbs are a new rev3 layout. I will be shipping rev3 pcb with all BlueFlyVario_TTL_GPS_v10 orders from now on. 

The rev 3 pcb incorporates the following changes:
  • Improvements to the ground plane under the GPS. This means that I removed the external pads for hacking to communicate with the GPS. If you want to get super serious about customizing your GPS you will have to solder to the PA6H pads instead. I am pretty sure that will only affect less than 1% of users.
  • Added Tx/Rx resistors for communication between the micro-controller and the GPS. This reduces noise on those lines.
  • Added an extra cap and ferrite to the power supply to make an LCC filter (600 ohm ferrite, 1uf, 0.01uf)
  • Moved the pressure sensor a little to make the neoprene fit over it better.
  • Moved the blue (or red) LED away from the pressure sensor.
All of these changes reduce the power supply noise, which in turn should improve the GPS performance. I remain confident that the rev2 board works well, but this new board should be just a little better. I have attached a schematic and layout below.

Wednesday, 31 December 2014

BlueFlyVario_USB_v10 released

Almost a year ago I started planning for an audio only vario to complement the original BlueFlyVario. I got a little distracted keeping up with orders of the Bluetooth version and the TTL_GPS (because of Kobo vario revolution). I started planning an audio vario again about six months ago. After settling on features, testing and producing an initial batch I am now very happy to announce a limited release the BlueFlyVario_USB_v10.

Design Philosophy

When designing this new vario I wanted to achieve a few things:

  • Build on the work of the successful Bluetooth model by providing a simple device designed for audio output. The firmware is pretty much the same as the Bluetooth and TTL_GPS models. 
  • Make it smaller. I wanted it to be easily able to fit in a helmet. I think this is the smallest vario available for purchase - it is about the size of a AA battery. 
  • Power with a rechargeable battery. Replacing batteries is a pain, but recharging is something we are really used to with our phone. The vario has a micro-USB connector which is the same as most phones. 
  • Provide a simple interface to alter the hardware settings. I considered having a separate USB-to-TTLSerial converter, but settled on incorporating a FTDI FT230X chip to provide an onboard emulated serial port. This only costs a few extra dollars, and does not take up too much board space (especially since I have now moved to using 4 layer PCB's). 
  • Expose the spare UART and audio interface for hacking. 
Because of all of this it ended up being more than just another audio only vario. The USB interface to change hardware settings and hack-able features makes it much more useful. 

Key Specifications

The BlueFlyVario_USB_v10 key features are:

  • Sensitive MS5611 pressure sensor with 10 cm resolution. 
  • Pleasant sounding audio tones, similar to fully featured varios. 
  • Onboard electromagnetic micro speaker (loudness 95dB). 
  • 250mAh rechargeable LiPo battery with 1.25mm Molex connector. Lasts about 10 to 20 hours depending on audio settings. Fully charge in about an hour. 
  • Onboard FTDI FT230X USB Serial chip. The device appears as a serial port with default drivers on most operating systems.  
  • Mass of about 9g. 
What is in the bag?

You need to do the final assembly yourself. You get the following bits in the bag:
  • The main module. This is 50mm x 12mm. 
  • A small piece of neoprene. This is really important. It must be placed over the pressure sensor if the sensor is exposed to any light. The neoprene allows the air pressure through, but stops the light. Light makes the pressure sensor go crazy.
  • A small 250 mAh battery. This is a single cell LiPo with a 1.25mm Molex connector. 
  • A small piece of blue PVC heatshrink. The simplest of cases is all you need. 


    Assembly should only take about five minutes:
    • Step 1 - Attach the battery. Remove the cover of the double sided tape and stick it to the bottom of the circuit board. See the placement in the image below.
    Battery placement
    • Step 2 - Do a quick test. At this point press the button to turn it on. You should hear a few beeps. The number of lower pitch beeps between the high pitch 2 second beep and short 0.5s beep indicate the battery voltage (6 = full, 1 = almost empty). Press and hold the button for 3s to turn it off.
    • Step 3 - Cover. Place the small piece of neoprene over the pressure sensor then encase the whole device in heatshirk. You will need to open up the heatshink to fit it over the button. Make sure the neoprene is covering every part of the sensor. 
    Neoprene placement
    Heatshrink placement
    • Step 4 - Shrink. Use a hairdryer on hot or a heat gun on very low to shrink the heat shrink. The switch might turn on. After shrinking, carefully slice the heatshink from the top of the switch, then shrink a little again. Test again to make sure the switch is working. 
    After shrinking
    Slice heatshink from top of switch
    A neat little circle
    After shinking again around the switch
    • Step 5 - Charge the battery. Plug in to a phone charger to charge the battery. The red LED will come on, then turn off when fully charged. [Note that as soon as you apply power to the micro-usb port that the device will turn on. This is because of stray current from the FTDI chip into the uart on the micro. Every ten minutes when on charge it will power down (based on the auto off feature), then power back on. The auto-on with recharge was an 'unintended feature' of this design. I might change it in the future with a couple of extra resistors in the design.
    • Step 6 - Alter the hardware settings. Most people will probably want to change the sink alarm from the default -0.2 m/s to something like -2.0 m/s (this stops the annoying sink alarm and reduces power consumption). Visit the support page of the website to download the BFV desktop app and the hardware settings manual to understand how to do it. 
    Advanced Use

    There should be a whole bunch of other things that this vario will do for advanced users. The pressure stream coming from the vario means that if you want to use it with an external application like XCSoar then it should be possible, provided the FTDI device enumerates properly on the device. This is only possible on Android/Kobo with some software hacking which I have not done yet. I have not tested this yet on anything other than the desktop version of XCSoar

    At some point I will update the BlueFlyVario Android app to allow the device to be used with a USB OTG connector.


    Like always; I share the design. Intrepid hackers might attach a GPS to the exposed U1 UART port or an external speaker. SJ1 and SJ2 provide for different power options. See the images below. 

    Friday, 12 December 2014


    From version 10 the BlueFlyVario models include a bootloader so you can upgrade the firmware. The firmware is the chunk of code on the microprocessor which makes the Bluefly wield its magic. Current firmware versions use about 60% of the code space on the microprocessor, so there is some flexibility to add a few features within the limits of the hardware. Normally you need a special microcontroller programmer to update the firmware, however with the bootloader you can do it over a serial connection without the special programmer. In this post I will describe how the the bootloader works and how to update the firmware.

    The ds30loader bootloader

    The bootloader is a small section of code which runs before the main Bluefly code. For a whole range of reasons I selected the ds30loader that Michael worked on a few years ago as an open source project (it is GNU licensed, it is used in other devices, I could make it work... etc. ). This same bootloader is used in the bus pirate and other open products. Since Michael did the open source project the bootloader is also available in a commercial version, but I used the GNU licensed one as I wanted to customise it.

    You can download the modified source code for the bootloader from my github. You do not need the source, but some people might find it interesting. The source for the bootloader is in assembly and is set up as an XC16 MPLABX project. The bootloader is modified from Michael's original version with the following features:
    • The various settings (configuration bits, timeouts, processor, etc) recommended to be adjusted have been made to match the Bluefly hardware.
    • The bootloader mode will only be entered if RA0 is positive. This corresponds to programming pad #5 on the Bluefly hardware (PGEC). As programming pad #2 is positive then the bootloader mode will be entered if pins #2 and #5 are shorted.
    • When in bootloader mode the green LED is lit but there are no normal startup beeps. This provides some feedback so you know you are in bootloader mode.
    To use the bootloader you will need the ds30loader gui PC application. You can download it directly from here.

    Firmware Versions

    The firmware is contained in a .hex file. From version 10 I started a new numbering system for firmware. I will put all version 10 firmware versions on the support page of the website. The numbering scheme works like this:
    • BlueFlyVario_{DEVICE_TYPE}_v{MODEL_NO}.{TYPE_NO}{SUB_VERSION_NO}.hex where:
      • {DEVICE_TYPE} = Bluetooth, TTL_GPS or USB
      • {MODEL_NO} is associated with a particular series of hardware. (i.e. version 10 for the version 10 models).
      • {TYPE_NO} is associated with the DEVICE_TYPE (Bluetooth = 1, TTL_GPS = 2 and USB = 3).
      • {SUB_VERSION_NO} is the version of the firmware.

    For example BlueFlyVario_Bluetooth_v10.102.hex is the second release of firmware for model 10 Bluetooth hardware.

    Step 1 - Get the software

    Get the ds30loader gui application using the link above and make sure it runs on your pc. Download the right version of the firmware you will need.

    Step 2 - Prepare the hardware

    You will need access to the programming pads on the pcb so you can short pads #2 and #5. You might need to disassemble the Bluefly so you can access the pads. A small hole in the heatshrink might be sufficient. See the image below for an indication of which pads I am talking about.

    You will also need to establish a serial connection. You can test your serial connection using the BFV Desktop application or a terminal emulator like Realterm:
    • Bluetooth version: you should add the vario as a device to the PC (you might need to use code 1234 to pair it via the Devices and Setting menu, it depends on your Bluetooth adapter). You will need to work out what serial port it was assigned by looking at its properties.
    • TTL_GPS version: you will need a TTL to serial adapter. Depending on how you installed the TTL_GPS you might need to solder things. Again you need to work out what serial port the TTL to serial adapter has been assigned.
    • USB version: the serial port is assigned when the device is first connected to your PC.
    Step 3 - Open the ds30laoder application

    Open up the ds30loader application. Adjust the settings to match the following:
    • Hex file: Browse to the location of the firmware hex file you downloaded (make sure to unzip it)
    • Device: PIC24F
    • Model: 32KA301
    • Baud: 57600
    • Port: What ever serial port you plan to use based on the one you determined in Step 2.
    • Write flash: Checked
    • Flow control: None

    Step 4 - Start up the Bluefly in bootloader mode

    You will need to short programming pads #2 and #5 then power on the Bluefly module as described in the image above. You should just be able to use a paperclip bent appropriately.
    • For the Bluetooth version, press the power on button while the pads are shorted. As soon as the green led lights up solid you can remove the short. 
    • For the TTL_GPS you will need to power the module using something like a TTL to Serial adapter. Press power then when the green LED lights you can remove the short. 
    • For the USB version it will power on as soon as you attach it to the USB port of your PC, so make sure the pads are shorted when you attach it (you might need three hands).

    If the green led lights up and stays lit you are in bootloader mode. You should not hear any of the normal beeps associated with startup.

    After entering bootloader mode you have 60 seconds to complete the next step. If you do not program within 60 seconds the device will exit the bootloader mode.

    Step 5 - Program the device

    Press the Write button in the ds30loader application. The application should connect to the Bluefly and start programming. It takes about 20 seconds.

    When programming is complete the Bluefly will start like normal with the new firmware. You can connect it to the BFV Desktop application to confirm the new version is uploaded.

    Saturday, 29 November 2014

    Kobo Glo Install

    I finally got around to installing the BlueFlyVario_TTL_GPS_v10 in a Kobo Glo. Most of the install procedure is the same as the Kobo Mini using earlier versions of the Bluefly. Unfortunately, the Kobo Mini is becoming hard to find. I choose the Glo instead of the Touch as the bezel has more room for the Bluefly. Also, I think the battery is larger to power the LED backlight on the Glo; although we will not use that light for XCSoar

    What you will need

    Gather the following things:

    • A BlueFlyVario_TTL_GPS_v10 module. You will not need header or Dupont connector that comes with it; but you will need the small piece of neoprene, some wires and some heatshink if you do not have a case. 
    • A Kobo Glo.
    • A Bluefly Kobo Glo Simple Case, you can download this solid design from Thingverse. Find a friend with a 3d printer or order a copy from an online 3d printing service. I had to update the older Kobo Mini Simple Case as it did not fit well on the Kobo Glo. [The case is not really needed, it makes the install look nice. You can of course just use the heatshrink]
    • Some countersunk M3x6mm screws and hex nuts to attach the case to the Glo. 
    • A good soldering iron and some skill using it. 
    • A drill and the right size drill bits. 
    Step 1 - Set up XCSoar on the Kobo

    This procedure starts pretty much the same as Steps 1 to 3 in this earlier post. Get the Kobo, make sure it works as a standard eReader, then remove the back cover and back up the internal SD card. Note the back cover of the Glo just pops off (with some uncomfortable force), there are no screws. After the SD Card is backed up install XCSoar as described on the XCSoar download page. When XCSoar is working power off the Kobo. 

    Note these funny things about the Glo:
    • The power button on the Glo is a bit weird when the back cover is removed. You might have to squeeze the PCB towards the power button to get it to work. 
    • When the Glo has been powered off, from either XCSoar or Nickel, you need to wait about 20 seconds until the power button will work again. 
    • Sometimes Glo freezes at the start-up screen. A short press on the reset button (the hole near the USB connector) will restart it back to the XCSoar menu. 
    Step 2 - Solder the BlueFly module to the Kobo

    Start by soldering the four wires to the front of the Bluefly module. The wires will wrap around the edge of the module and through a hole in the front of the bezel. There is much less room behind the bezel on the Glo compared to the Mini. Position the case and module and it should be reasonably easy to work out where to drill the holes for the wires. You might use a bit of double sided tape to hold it in position. 

    Trim the wires then solder them to the Kobo. Make sure to connect the Bluefly-Tx to the Kobo-Rx and vice versa. 

    Note that there are two other serial ports on the Glo which you might be tempted to use - don't. For some reason any data on these ports causes the Glo to freeze. 

    In this install we are not going to use the VBACKUP for the GPS as it is tricky to pick up clean power without damaging the Glo. If you really want to connect it then spend some time Googling and find examples of soldering it to capacitor C12. 

    Step 3 - Install the Simple Case

    After drilling the holes make sure to put the neoprene over the pressure sensor. Secure the case to the bezel using M3 screws and nuts. 

    You will need to trim some of the plastic fins from the back cover and around the nuts to make sure it all fits together. 

    Step 4 - BlueFly Configuration

    Follow Step 8 from here to configure the hardware settings. I think it is best to set the Bluefly to output mode 2 at five updates per second, then adjust the settings in XCSoar to use the LX driver. This minimizes the amount of data. 

    Using it

    Note that by default the Bluefly will only power on and off based on button presses. If you wanted the Bluefly to switch on and off as the Kobo is powered on and off then you can close the solder jumper on the Bluefly module.