Meko Music Player

04.29: chose the soc, and usb uart switchin

• choose the esp32-mini-1u because it has support for bluetooth audio and rust
• this chip doesn't have an integrated usb controller, so I had to choose a chip for usb to uart

Total time: 1.5

05.05: added the dac/amp chip, added display connector

• there is little info on high quality dac/amp chips, after many days of research and pain a choose the ES9218P, which is a really nice chip to work with, but the datasheet is a bit lackluster
• chose a display, added the flex pcb connector for it

Total time: 2h

05.07: added the hall-effect sensor for the wheel

• I saw a wide where a guy made a high precision scrolling device, and he used a hall-effect sensor, I chose to go down this rout because there is no rotory encoder to ware out

Total time: 1h

05.08: power, lil bit

• Copy pasted bms and power path chip from previous project, did some calculations, changed resistor values

Total time:1h

05.09: power and usb

• Chose a dual output switching regulator, implemented usb to uart chip

Total time: 1.5h

05.10: audio

• Read the datasheet far more times than i would like to admit
• Some things are not clear
• implemented the things that I kind understand
• asked a question on stackexchange

Total time: 1.5h

05.17: some Chad replied to my question on electronics stackexchange.

• Someone who has experience with this rare chip, YIPPPEEEEEE
• I will have to use a oscillator, not a crystal, and low noise LDOs instead of switching regulators
• Did some research on mems vs oscillator vs crystal

Total time: 2h

05.18: implemented to suggestion from stackexchange

• oscillator instead of crystal
• added low noise LDOs

Total time: 2h

05.22: Added components, choose LDOs

• I switched from a esp32-mini-1u to a esp32-pico-mini-02, for an integrated pcb antenna and a smaller from factor
• Chose the micro SD slot, and added it to to the schematic
• the same chad from electronics stackexchange replied to my other question about power delivery for this chip
• Did a lot of datasheet reading abot LDOs and what to choose, and decided that will try to solder 1mm*1mm packages

Total time: 3h

05.23: Power, power, POWER

• implemented the LDOs
• learned a lot about filters, low-pass, high-pass, etc. Interesting topic
• again lots of reaiding

Total time: 4h

05.24: inter chip COM

• the esp32 has a f#$* up io multiplexer if you want to do multiple things
• the SD card pins and the JTAG pins are the same, so if you use an SD card you cant use JTAG, or vice-versa
• all of the pins that can output a i2s clock signal are used by uart or the boot pin
• might need to figure something out for using the same pins for different things
• wired up the hall-effect sensor, en and boot pins with the usb-to-uart adapter, some parts of the dac/amp chip, SD card
• created a symbol for my display
• read a bunch again

Total time:5h

05.25: finishing up the schematic

• finished display, aka copied reference design
• turns out you can you can use gpio0 as a regular gpio0, you just need to make sure that it doesn't get pulled low on boot, so my i2s clock is on gpio0 (aka the BOOT pin)
• chose the headphone jack, and added the footprint and 3d model
• still need to add esd protection in some places
• added buttons
• routed spi for the display, added test points
• i dont have enough gpio to controll the DACs power chips, so they will all start up at once, which is not optimal, but....
• i need to connect up the headphone jack

Total time: 3h

05.25: I'M ALMOST DONE

• added an I/O expander, because i ran out of I/O
• added led, and haptic motor
• since i added a io expander now i can control the boot sequence of the dac/amp
• added more esd protection
• researched how inline volume controls work
• segmented schmatic

Total time: 5h