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The Build - 4 - Building the Logic

This part of the build is the most complicated and delicate. Be patient and don't rush it. There are a lot of ways to fry your parts, or create a hidden solder jump that can take an hour to track down. Use the micro wire for all the connections here. The wire is single core, and can break easily. I suggest using super glue to keep wires in place after you have soldered them, reducing flex stress on the wires, especially at solder joint points.

The top of a completed logic board logo

The bottom of a completed logic board logo

Step 1) Pre solder the BLE112 chip
You will need flux for this. Once you place the BLE112 chip in the frame, it will be harder to solder, so if you can cover the connections with solder before, it will be easier to solder once it's in the frame. Make sure you only use a little solder, and do not create any shorts (Use a multimeter to confirm)

Step 2) Place and glue the 3 boards into the 3D printed frame.
use as little glue as possible. You may have to shift them a bit, and if you use too much glue, that will be hard. I suggest just at the corners. Also make sure that you do not glue over any of the pins (Especially on the BLE112 chip) and make sure that there is room around the frame for wires to reach the BLE112 chip. Depending on your frame print quality, you may need to use a soldring iron to "make more room". If you need to do this, just be careful. The plastic is thin and too much heat can warp it.

Step 3) Connect the BLE112 to the Microduino

The Top Down Pin Guide of the BLE112 logo

Here's a link to the BLE112 Datasheet - DataSheet 1 - GND - Microduino ground
2 - AVDD - 3.3v power Supply
3 - AVDD - 3.3v power Supply
8 - p1_6 - Pin 5, Module Wake up
13 - p1_5 - Pin 7, Arduino Wakeup, not used Currently
20 - DVDD - 3.3v power Supply
23 - P0_5 - Pin 2 / Software Serial RX
24 - P0-4 - Pin 3 / Software Serial TX
29 - Reset - Pin 4

Flux, Flux, Flux! You also want the wires to be run as flush as possible. The goal is to keep the wires from increasing the height of the frame. Use the soldering iron to create small grooves in the frame to let wires pass.

For wires that connect to ground or 3v3 power, bring them to the connection points, and glue them in place, but hold off on soldering until you have other wires that may go to the same pin.

Step 4) Connect the BLE112 to the programmer dock

The Pin Guide of the BLE112 logo

4 - p2_2 - To Programmer
5 - p2_1 - To Programmer
Ground, reset, and 3v3 power also needed from programmer, and can be shared. (Wire the programmer pin ground to the microduino ground, connect 3v3 power to the microduino pin 3v3 (also where you connected the BLE112 chip to power), and connect the microduino recent BLE pin to the programmer pin.

You can make the dock by glueing 5 female jumpers together, then cutting them short. (see picture)

Step 5) Test it!

If you have soldered the basic programmer connections in, you can confirm that you can write to it, using a CC Debugger. Here's a great blog article on how to do this. Programming BLE112 with CC Debugger

Use the prewritten files from Here to test it. (You will need this Library anyway.

Step 6) Wire up the power and Microduino programming dock

The Microduino Programming Dock logo

The external programming dock lets you write to the microduino. The connections are straightforward:

RTS Pin - RST pin on Microduino (add a 10mf capacator on the reset line externally)
TX Pin - RX pin on Microduino
RX Pin - TX pin on Microduino
Ground Pin - ground pin on Microduino
V in Pin - Voltage input pin on Voltage regulator

Once you have those connected, bring the V Out and Ground on the voltage regulator to the 3v3 vin and Ground of the microduino. This should let you plug in and program the microduino!

Step 7) Add the 3 buttons

The 2 puttons on the right of the watch rely on internal pullup resistors, to minimize extra hardware. The buttons simply connect the two input button pins to ground when they are closed.

The 3rd button will be used to interrupt the microduino out of any sleep mode it may be in, and uses an external pulldown 10K ohm resistor.

The Button Pull Down resistor (hidden in electrical tape) logo

The Interrupt based button connects 3.3v to Pin 6.
The top button connects ground to pin 14, and the bottom to pin 15

Now you should have a complete Logic Frame! You can upload the basic code to test it, as it will function without the screen. You should be able to test the basic connection to an iOS device at this stage.

Next Page - Building the back

The Build