When finished, device will be fully functional mobile music player, inspired by the media players from first decade of XXI century, mainly an iPod. As you probably already figured it out, name of the project is a pun - you read "yPod" like "why pod" and the answer is obvious - "Because i can [build it]. ;)
Device is mounted on two layered, homemade PCB, made with a laser printer and thermal transfer method. Yes, I know there are companies that will produce small number of professional looking boards for a very small price, but I simply didn't want to wait for a package arriving from China. Anyway, this is probably one the last that complicated boards, that I ever etch by myself...
The "heart" of the device is the STM32F407 chip, which is powerful enough to handle all the heavy tasks like decoding audio streams and generating graphics, so I decided to not include hardware MP3 decoder in this project, opting for a I2S audio codec (WM8731).
Player is designed to support up to three media storage devices:
- SD card connected to SPI bus (it will serve as an internal storage)
- SD card connected to SDIO bus (external, removable media)
- External USB storage.
The interface will be shown on 240x320 LCD screen. There is a possibility od adding touch screen later on, but main function will be controlled with buttons and rotary dial.
Of course device is powered by the battery charged with micro USB charger. To preserve power I decided not to use linear regulators. Required voltages of 3.3V and 5V (for USB) re being produced by the switching converters.
At this point hardware is nearly complete and tested. I just need to order one part to finish building USB power circuit. Then writing the software will be the only thing to do.