Building the ProMini Air
Click on any of the photos to show a larger image
First step is to solder on the Voltage Regulator. Use an alligator clip (or similar) to hold the small chip in place and solder the three lower pins. Don’t worry about the tab, it’s not connected to anything. Another method is to superglue the tab, once it’s dry, solder the three lower tabs.
Install the Pin Headers for the ProMini. Break the long header pins off for the correct length for both sides. Solder one pin, check alignment, tweak if required. Then solder all of them in. Long side up is the best way, this gives you good access to all of the signals if you want to take a look at them. Note that the two pins at the top of the ProMini will have to be trimmed so the programming adapter fits.
After the pins are soldered in, do a test fit for the Arduino board. After making sure it fits, (it should go in easily) remove the Promini and solder in the header pins (at the top of the board). This will let you plugin the the Sparkfun FTDI Basic Breakout Board
(as shown) to attach to the Pro-mini. This has already been done in this photo. This is the programming interface.
Solder in the resistors. These are voltage dividers so we can interface the 5v promini outputs to the 3.3v inputs of the CC1101 modem. Note that the 20K resistors are the ones held together with the paper strips, the loose ones are the 10K ones. If you get them confused you can google the color codes to make sure.
After the resistors are soldered in and the leads trimmed off of the bottom, solder in the servo/DCC connector pins.
All soldered in.
All that remains now is to solder on the main components. After I soldered it in, I clipped the CC1101 pins as they protrude pretty far under the board but it’s not required.
The completed board for reference.
The input board. This will take any DCC signal out of a commercial (or other) DCC controller and transmit it out over Airwire. You only have to change one flag in the software download and the CC1101 becomes a transmitter. (more details soon)
The input board tied to a commercial DCC system.