Sunday 15 January 2017

BlueFlyVario_Bluetooth_USB_v12 released

The first batch of the new BlueFlyVario_Bluetooth_USB_v12 model has been produced and all pre-orders have been shipped. I announced in the last blog post the new features of the v12 compared to the v11. In this post I will provide a more detailed description of the new design and describe the assembly procedure.

What is in the bag?

The v12 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. 
  • The sky blue enclosed case. 
  • A 750 mAh singe cell Lithium Polymer battery. 
  • 4 x 5 mm M3 black nylon hex standoffs and 4 x 5 mm M3 black nylon screws. 


Assembly

Assembly is pretty simple and will take most people less than 10 minutes. I still recommend the procedure described in this previous blog post, but I have refined a few of the steps as described below:

Install Step 1 - Prepare the case 

[Optional] The first part of this step is only needed if you want to put a small lanyard on the vario. Drill a couple of holes into the case at the opposite end from the USB cutout. Use a slow speed drill and only the force needed. Make sure the holes are not too close together or the small plastic in between might break if you use too much force on the lanyard. Size the holes according to whatever cord you will use. Note that on the v12 the mainboard is slightly longer than the v11 so you will need to drill the holes so that the lanyard is under where the circuit board is going to be close to the end of the case.


Next you will probably want to slightly enlarge the inside of the USB hole. I use a sharp pointed knife and just remove a small chamfer from all of the inside edges of the USB hole as shown below. This helps the micro-USB connector fit in nicely.


Install Step 2 - Screws and standoffs

Screw the hex standoffs and screws into the BlueFlyVario_Bluetooth_USB_v12 module as shown below, but be careful not over-tighten the screws; finger tight is normally enough. The hex standoffs keeps the module properly spaced from the base of the case.  You can shorten the standoffs by about 0.5mm with a sharp knife to improve the fit into the case.


Install Step 3 - Place it into the case


This is the only tricky part. Use only the force needed to place the module correctly in the case. It is possible to break either the button or the usb connector if you use too much force. Place the module in the base of the case so the button protrudes from the hole. You may find the USB connector will need a little pressure from above to push it into the hole. The edge of the PCB should be close up to the cutout end of the case and the USB connector shroud will move into the cutout (as shown below). Also see the photo from step 3 in this previous post for more information about where to gently press on the main board.  


Install Step 4 - Packing material

Put something at the other end of the PCB to keep it pressed against the USB cutout end of the case. The gap on the v12 model is about 1-2mm and I use a small piece of paper folded and placed as shown in the image below. Note the small lanyard threaded below the board.


Install Step 5 - Battery

In the v12 there is no longer any need to use double sided tape to secure the battery to the board as the lid holds it in place. Note the wires need to be neatly folded and placed as shown.


Install Step 6 - Close the case

Place the top on the case (which is now the bottom in the image shown below). I now normally run clear tape around the case to ensure the lid is held in place; this is shown as brown kapton tape below so it stands out in the image. On the v12 the battery fits snugly, and if you do not slightly shorten the standoffs in step 3 then the lid might pop off just when you don't want. 


Plug it in to recharge. The red light should come on. A single press on the button will switch it on, and a long press will turn it off. See the Hardware Settings Manual for more technical setup. 

Install Step 7 (optional)

Some pilots like to mount the vario on a flightdeck. You can use a 50 x 30mm piece of velcro (not included). To make velcro stick better heat it up with a hairdryer prior to sticking it on.


--- Technical Stuff ---

For most pilots, this is about as far as you need to read through this post. However, if you want to get technical and understand more about your BlueFly then read on. 

Firmware Changes

There are not too many firmware changes relevant for users between the last firmware from the v11 (see here for 11.M13), and the first firmware for the v12 (12.M14). In summary:
  • The UART related code has been updated to change the way data is sent with the new analog switch. It works like this:
    • If Bluetooth is not connected data is only sent and received from the Bluefly via the USB-serial chip. 
    • If Bluetooth is connected then data is sent to both the Bluetooth and USB-serial connection, but only received from the device connected via the Bluetooth connection.
  • The default hardware settings have been changed, particularly some of those associated with audio thresholds. They now reflect my preferred settings. At some stage I will update the hardware settings manual. 
  • Changing the secondsBluetooothWait hardware setting now re-enables the bluetooth module if it has been disabled. 
Hardware Design

The layout of the key components on the mainboard is described in the image below:


Some key changes from the v11:
  • The addition of the FTDI 230X USB-Serial converter now enables a data connection in the miro-USB port (instead of just charging). This makes it much easier to adjust hardware settings on a Windows PC. 
  • The addition of an analog switch controls serial data sent as described above in the firmware section. 
  • Components are spaced better and aligned more neatly. This is not just for visual appeal, but is is a 'design for manufacture' feature which makes it easier for me to assemble. 
  • The board is now about 3 mm longer, and the holes have been moved a little closer to the corners. This maximizes the space available for components and the board fits better into the sky blue case. 
All of the exposed pins are now in one row along the top side as shown in the image of the bottom of the board below:


Some key points:
  • You will not use the programming pads for the PIC or the RN4677 unless you are a super hacker and writing your own firmware from scratch. 
  • The external speaker connector is for when you want to remove the micro speaker and use a separate 16 ohm speaker. You might be able to use a 8 ohm speaker but you will need to check the levels with your test equipment and you might need to change the resistor biasing the transistor. 
  • The USB PWR jumper should be closed ONLY if you want to power the BlueFly solely from the micro USB connection, and not use the battery. DO NOT CLOSE IT WHEN USING A BATTERY - because if you did then unregulated 5V power would be provided directly to the battery which might case it to fail. 
  • Along the right:
    • The U1 V+, Tx, Rx, Gnd connectors are for connecting an external GPS as described in previous blog posts. I am considering new shields for this model. 
    • The I2C V+, SCL, SDA and GND pins are used for connecting the airspeed sensor described in previous posts. In future versions of the firmware this might also be used for other external devices. 
    • RA7 is a general purpose digital IO which is currently used for enabling and disabling an external GPS connected to U1. 
    • RB10 is a general purpose digital IO which is currently used for the calibration button on the airspeed shield. 
    • RB11 is a general purpose digital IO which is used for an indicator LED on the airspeed shield. 
    • RB4 can be a general purpose digital IO or provide an analog input. The firmware does not currently read it, but in the future I am planning to add some code to read the analog input from something like a fuel level sensor. 
    • BTN is connected to one edge of the main button. A momentary connection to VBAT will power up the vario and enable the voltage regulator. Subsequent momentary connections will then simulate a button press. 
    • VBAT is connected to the positive supply for the LiPo Battery. 
Future work

You may be able to tell that am  hopelessly addicted to trying to make the BlueFly better. Expect more stuff in the future - let me know your ideas.