Wowee this is the home stretch! This is do or die territorry and a wrong move will cost me the completion of my final project >.< This week, I'm going to write to and read from an external flash memory IC with the ATxmega using a prototype of my final board (which will probably just become my final board to be completely honest). In the previous weeks my plan was to simply have the microphone and speaker communicate via serial bus, but this then I realized that the memory uses SPI, which should take a week's project to learn.
DATASHEETS DATASHEETS DATASHEETS... I swear everytime I read a datasheet I catch something I missed before. Anyway, I ordered this DAC for my final board, but on the fifth read-through of the datasheet I realized that it needs a power supply (plus and minus voltage), which wouldn't work since I am powering it with a battery. So in my final board design, I am using an ATxmega, which has a built in DAC that I am then using an op amp to boost to a [0, 4.95] range.
In addition, upon reading more of the datasheet for the audio amplifier I realized that it is made for AC analog audio, not DC. So instead, I used the gem of an instructable I found for Week 10's speaker circuit to make my amplifier.
As you can see in the phalicity of the design, I wanted to have the programming headers jut out. Part of the novelty of my idea was that once you pressed the button to record it the first time, it would have a sense of permanence. Like you have to think about your what you want to record. And part of that would be the idea that the programming pins snapped off when you pressed the button. But alas the design never worked out that way! When printing my first board I opted to keep the snap-off design, but make the snap-off tab much smaller.
For the keen eyed readers that notice way too many details, I also used Eagle for the first time because 1) I wanted to be able to visualize my board in conjunction with my Fusion360 model and 2) I know I'll need to use the SRM for milling my molds, so using the othermill to mill the board would be helpful. Except BOTH OF THESE THINGS TURNED OUT TO BE WRONG! The software to do the conversion from ECAD to MCAD needs subscription/free trial and the 3D libraries aren't even complete. Also, the othermill crapped out on my board alone! I hate Eagle for these reasons: 1) design rules aren't automatically enforced, 2) lack of one-key shortcuts, meaning you have to use the mouse to click options and then manipulate, and 3)