Step 9: Test the finished board
-Completed watch PCB
-3.7V 240mAh Li-polymer rechargeable battery. Ordered from HobbyKing for about $2 plus shipping.
-Soldering iron and solder
-Cut two pieces of magnet wire and solder them to the battery. Magnet wire is very thin and will not take up much space.
-Wrap some masking tape around the battery connections to prevent the leads from touching the PCB.
-Next, solder the positive end of the battery to the +VCC pad and the negative end to the GND pad
The battery should have a + and - labeled on it somewhere
**Be careful when using Li-polymer batteries because they can explode if punctured. They will also overheat and possibly explode if you happen to short it out.
SET THE TIME:
-Once the battery is connected, the 2 LEDs at the 12 O'clock position should light up like before.
If not, plug in a USB cable to charge the battery. The LED on the back of the board will turn off when finished charging.
-If the LEDs do light up, try programming the time:
*Press and hold the top left button for a few seconds (the LEDs will start flashing)
*Use the buttons on the right to increase or decrease the hour
*Press the top left button once to cycle to program the minute
*Use the buttons on the right to increase or decrease the minute
*Scroll through all the LEDs to make sure they are working
*Wait a few seconds for the LEDs to stop flashing
If some, or all, of your LEDs do not light up you more than likely soldered them in backwards. Or one of your components is not properly soldered in place. Still, it is possible you have a short somewhere.
The best way to troubleshoot is to make note of which LED(s) is not working, look at the schematic, and see how it is supposed to be connected. Using a multimeter, test all the connections that the LED needs to make in order for it to match the schematic.
For example, if the LED needs to connect to a resistor, touch the end of the LED and the end of the resistor with the multimeter.
When making my boards, I found that the most common mistake I made was not completely soldering all the pads on the ATMega328P chip. If this is the case for your board, use a multimeter to check the connection by touching the pad itself, and to a component it is supposed to connect to. If the continuity tester does not beep, then add more solder to the pad.
Still, there could be other problems that are harder to detect such as:
-A faulty component.
If an LED still does not light up after troubleshooting, touch the pads directly with a 2AA battery pack (or similar power supply) if the LED does not light at this point, you have a bad LED that needs to be replaced.
If you're not careful it is possible to fry your ATmega chip. These chips are pretty tough compared to other chips, but it can still happen. There really is no exact way to be sure but if you cannot upload a sketch then its a pretty good indication.
-A faulty board.
Depending on the criteria you sent to the board house that made your PCB, some of the connections could be off. This happened to me with one of the boards I ordered from Seeedstudio. When I ordered the boards, I chose a 50% E-test, so they did not perform a complete inspection of the boards after they were made. It would cost $10 more for a 100% E-test, and all the board would be in perfect working order. So it really wasn't the company's fault. But hey, 10 boards for $10 and only one mistake sounds like a good deal to me.
The error I had was with one of the vias. It was not making proper connection between the top and bottom of the board. Once I figures out what was wrong with the board, it was an easy fix.
I first used an xacto knife to scrape the top coating from both sides of the via to expose the copper pad. Then, I inserted a thin strand of wire into the hole. Finally, I soldered both ends and trimmed the excess wire. Good as new!