Hey there, welcome to the first journal entry for my own MP3 player!
Obviously, the start is usually the hardest part (hey, that rhymes!).

I started with some research through the depths of AliExpress to figure out some basic things first: what audio jacks can I use and how am I going to display the necessary information? What screen am I using? Having absolutely no idea what I was actually searching for, I took a (somewhat) deep dive into the world of screens to find out one thing - a lot of them are incredibly expensive - and the others are shitty :)

Also, I wanted not just a normal AUX port, but a 1/4” AUX port as well, if possible! I use studio headphones and would like to have a possibility to connect them as well (yes, I could just unscrew the AUX -> 1/4” AUX adapter but that’s uncool)

I ended up making a [part list] in my Slack channel #xvcfs-studio!

A few days later, I looked a way to connect headphones to my main controller - a Raspberry Pi Pico. Why a Pico, you might ask? Well, I got one from Haxmas recently and need a use-case for it (and it’s from Hack Club so that’s cool!). Back to audio though, I needed to find a way to somehow interact with the two audio jacks from the Pico. I did some research on the internet and found a chip from Texas Instruments that should be capable of doing, what I want it to do! The chips name is TAD5142. Clicking through the datasheet was less terrible than expected, to be honest it was quite fun! Thank you Texas Instruments for a good datasheet!!

Since I am using two AUX ports, I need an operational amplifier! Here, I decided to use a MCP6002-I/SN since it should work fine with the lower voltages I am using here.

I connected it and hopefully my wiring is correct and should work! I have attached a picture below, though the wiring of the TAD5142 is currently not finished.

My last step today was just some simple research on the microSD card connector. I figured that the connector I found on KiCad did not have a connection detector and also did not really seem to have a good datasheet on the manufacturers website. I switched to a different model that fits my needs (and has a better datasheet) and I’m going to finish wiring it soon!

Yay, a lot of work, but that’s it for now! This was super fun!!