Output Devices - Hello World Speaker

Intro to Speaker Board

For my final project I want to create an "interactive meditation pod." I envision that the interactiveness of the pod will come from some sort of meditation necklace or medalion that, when touched by the meditator, will speak a sound. As I want to include speakers into my final project, I thought that this assignment was a great entry into understanding the basics so that I can iterate and build on them for my final project. I first discovered this board by going to Emma Benjamin's output device page. I thought the "hello world speaker" from the class output device page would be the right place for me to start.

Milling the Board

I downloaded and saved the hello.speaker traces and interior from the fab class page. When I initially input the traces into the modella an error occured. After zeroing the z and setting x,y origin the drill seemed to drag across the board as you will see on the picture to the left. I tried this another time with the same result. Upon further inspection I think it was something that was happenng with the zjog. I am still not sure what was going wrong. Ultimately, I closed the fab modules and restarted and, luckily, third time was the charm! Ultimately, I was able to mill the traces and the outline to get a beautiful board to solder.


I thought soldering would be much quicker than the last time as this was now the third board I was making. Perhaps it was due to tiredness, but I was having a lot of issues with my eyesight and getting into a good flow with soldering. I even tried to use the help of a microscope, but still found it challenging to get clear view of the board. This board took me about an hour to solder, which I think is too long for the amount of components. For some reasone I had the most difficulty with the ISP. The traces on the backside of the ISP were close together and I didn't want to create a short. I had to use the braid to remove some solder and resolder a few times. This caused one of the copper pads to begin to lift. This made my quite nervous. I decided to use some tape to help stabilize the ISP on one side, while I solder the other side. I actually found the trick of using tape quite helpful with the rest of the board - particularly the capacitor, which has given me a hard time in the past.

Creating the Connecting Wires

For the speaker board you need two sets of wires (in addition to the wire for the FAB ISP that was created in an earlier week). One of the wires was going to go from the 2X2 header on the bottom left of the board to power. For this header the 2nd and 4th wires needed to be active. Wire 2 will go to power and wire 4 to ground. To make the wires I pulled a group of 4 wires from a 6 wire thread. I then pulled apart the ends of the 4 wires to seperate each. Next, I took the wire shredding tool to pull off the casing for my 2nd and 4th wires. I had to do this a few times to make sure I got it right. Initially, I was stripping the casing to fast and breaking off some of the smaller wires as well. Once I got it right I had the ends sticking out. I twisted the ends to help bunch them more securely and then encased the wire bundle with solder. I did this for the second wire header that would attach to the speakers as well. This time the wires for the speaker were in slots 1 and 3.

Soldering the Speaker

When I ran the inital test for the speaker there was clearly something wrong with how I soldered it. I think that I might have overheated the pads. The particular speaker I was using for my board had two metal bulbs on the back to attach the wires. I found it challenging to get a good hold on the metal bulb and the wires. In order to get it work I found I needed to place some double stick tape under the speaker and over the wires to hold everything in place (note: the tape was not near the area I was soldering, it was placed to allow for the wire tips to rest on top of where I needed them to be to solder). I found that you needed to get quite a bit of solder onto the metal bulbs in order for the wire tips to firmly hold in place.

Programming the Board

There were a few steps I completed when getting ready to program the board. First I used a multimeter to check the connections across the board. Next I used aligator clips to attach the power header to a power supply machine to check to see what would happen as I adjusted the current and voltage nobs. I was a bit nervous during this step and found it helpful to make sure both current and voltage nobs were all the way turned down when plugging in the board. Then I slowly increased the current - the screen still read 0.00 A, and gradually increased the voltage until it got up to 9Vs. Next Rob showed me how to use an oscilloscope to check to make sure the voltage was flowing properly to the speakers. After checking to make sure there were no soldering issues it was time to program. First I downloaded the makefile and C files for the hello.speaker board from the fab class page and saved them to the desktop. I opened the terminal on the MAC in the Harvard Lab and connected one of the available FAB ISB programmers. In terminal I called forward the following: avrdude -p attiny45 -c usbtiny. Then I entered the make file: make -f hello.speaker.45.make. Finally I called forward the program to the USBtiny: make -f hello.speaker.45.make program -usbtiny.

The Finished Product

The final product is captured below. IT is really powerful to hear the sounds coming from the speaker for the first time.