Bend the resistor into a staple and slip the wire leads into the two holes so that the resistor covers the outline labeled R10 in the bottom right corner shown here
With your soldering iron heated up and ready, solder in both leads of the resistor. To do this, heat up the round ring pad and the wire lead at the same time for 2 or 3 seconds, then dip the end of the solder into the heated joint to melt it in.
Then remove the solder and the soldering iron.
Ceramic capacitors, like resistors, are not directional. So put it in any way it fits, next to the R10 resistor, so its surrounded by the C1 outline
Then bend the leads and flip over the board.
All the resistors are the same 47 ohm value - Yellow Violet Black Gold
Here we placed and soldered all 8 at once but you can go one at a time if you want to take it a little slower!
This chip is the "real time clock" - the timekeeper. It is a ultra-lo-power circuit, whose only task is to keep track of the time, so its pretty good at it. It's possible to have the main microcontroller chip (the next one we'll do) keep track of the time, but its not as good at it (both in terms of power and precision) so we splurged on having a seperate RTC
The important thing about chips is that they are not like resistors and capacitors in that they can't be placed 'either way'. It must be placed the right way or the chip wont work. Look for the end of the chip with a notch and a dot. These must match up the silkscreened image on the PCB so make sure the notches line up.
The chip is an ATMEGA328P that has been pre-programmed at the Adafruit factory to have an Arduino-compatible bootloader and our default watch display code.
To begin, flatten the pins to make them more parallel || shaped intsead of A shaped. Hold the chip in your hand and press all the pins one side at a time against a flat table.
Then when you press it into the holes, make sure each pin has made it into a matching hole, and its sitting flat against the PCB
Like the RTC, this chip must be put in the right way. The notch on the chip must go on the left side as in these photos. Check twice to make sure you have the chip in right!
The battery holder does have a special way it must go, make sure you can slide the battery in by having the open side facing out
The crystal can go in either way, its symmetric, like the resistors
Also, solder and clip the two crystal pins
Both go on either side of the board, and they'll snap in.
Then flip the board over and solder in all 4 pins of each
The LED matrix is what you'll be looking at - 64 individual LEDs in a plastic case.
The Matrix is not symetric, it must go in the right way on the right side.
Look for the writing on the side of the matrix, this side must go on the side of the PCB with a dot as you see here. Also the matrix goes on the OPPOSITE side of the other parts!
Check that the 28-pin microcontroller pins aren't in the way of the matrix, it should sit nice and flat
You can clip the leads but you don't have to (they're less long than the height of all the other parts!
When you've got it all in, you may need to pull/press the band around the PCB to have the 'nubs' fit into the notches that are molded into the band
After you've assembled your watch there are a few ways to change the fit of the band around the PCB. First is trimming down the nubs on the PCB. These are there to help keep the board inside the rubber band. However, they may be long depending on your wrist size, and band (all the bands are slightly different)
Simply trim them down a millimeter at a time to help avoid them from sticking out too much
Kapton tape is a heat-resistant and electrically insulative tape that's used a lot in electronics. This isn’t included with the watch, but if you’ve been in this hobby for a while there’s a good chance you already have a roll handy. Wonderful stuff.
One or two layers of Kapton tape applied to the watch face make it less prone to washing out under bright light. The tape’s color is similar enough to the red LEDs that they shine through with little difficulty, while most ambient light is blocked.
Rubylith film (from a decent old-school art supply store) would probably work as well, if not better.