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Fixed alarm sound

I fixed the alarm sound. With the Senior Project clock, the buzzer and the buttons were connected to the same port. On the new clock, they were connected to different ports. I did not update the button reading routine correctly, so the buzzer output was not working at the moment a button was being read. This resulted in a little distortion being introduced into the signal going to the buzzer. This was easily fixed once I figured out what was causing the problem.

However, I made a discovery while troubleshooting this problem. While looking at the buzzer’s waveform on an oscilloscope, I saw voltage spikes being generated by the buzzer’s coil. I realized that I needed to add a diode to the circuit to protect the microcontroller from these spikes.

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Built the prototype

I assembled the first board, using a Zero Insertion Force (ZIF) socket for the microcontroller. The socket has a lever to release the microcontroller so it can be inserted and removed without any force. This allows it to be removed a lot easier for programming.

I adjusted the code for changes in the pin assignments and got the new clock working, except the alarm sounds strange. I suspect it’s a software issue of some sort, but will have to troubleshoot it later.

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Made frames

After making the jigs, I had enough wood left over from my sheet of MDF to make 40 frames. I had some issues which damaged some of the frames as well as mangling some of my jigs making them useless. However, I did end up with 30 good frames.

Now I know how to make the next set of jigs to avoid these issues, make the process faster and get more good frames out of my next batch!

I showed one of my frames to my friend, Denny, who made the frame for my Senior Project, and he said mine came out better than his. Looks like I got this part down! 🙂