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Neopod

Created by @lsyzg

MAY 24, 2025

GOALS

I thought of what I wanted to accomplish with this project, and made a quick list of all the capabilities I want for it: - Bluetooth capabilities, it should be able to connect to airpods or headphones - Headphone jack, if people want to use it - A microSD slot, so that you can load songs onto the microSD and quickly listen to music - A music player software such as mediamonkey that can manage the songs - 4 buttons all around a fifth button in the middle, similar to the format of an ipod, with the 4 around being navigation and the fourth being confirmation - A USB-c port for charging and connection to another device that can also load music onto the microSD card - A LCD display - Li-on battery - 3D printed case - Power button

CONCEPT:

NeoPod-concept

PARTS AND POSSIBLE ARCHITECTURE

  • So, now that I know what I want to accomplish, I should think of what components to use. After doing some research, I realized that an A2DP source is needed to send music over bluetooth to airpods, which an ESP32-WROOM32 would be perfect for. Paired with the ESP-A2DP library, I will have a fully functional A2DP sink.
  • Now onto the DAC, I will use a PCM5102 DAC and SJ-3523-SMT-TR barreljack.
  • The microSD slot will just be standard chassis.
  • For the 5 buttons, I might go for mechanical keys and keycaps with up, down, right, left arrows. I will use the Kailh Choc White V1 Low Profile Switches
  • The USB-C connector will be a 16 + 8 receptacle (USB4115-GF-A) that can transfer data and charge, which I will use a STC4054GR for.
  • If I want a method to debug over USB-C from my computer, I can use a CP2102 that is between the D+ and D- lines to convert USB to UART and send data over serial and charge the device.
  • For file transfer to the microSD, I will use a separate USB-C receptacle, a RP2040 with a 12MHz XTAL with 2 22pF capacitors, and a 4x multiplexer(SN74CB3Q3257DBQR) that switches access of the microSD between the rp2040 and the ESP32-WROOM when the cable is plugged in via sel pins
  • I will use a 2to 2.0 TFT LCD (ILI9341) that I can use SPI with
  • After some research, a 3000 mAh 3.7v li-on battery should be sufficient to run the NeoPod for a while
  • Add a momentary switch on the side to act as a power button, it will be connected to gpio0 of the ESP-WROOM so that it goes into and out of deep-sleep on press, use EXT0 on GPIO0

KICAD SKETCH

I sadded the ESP32-WROOM-32, PCM5102a, SJ-3523-SMT-TR, and the SD slot. Now I am trying to find a symbol for the Kailh Choc V1.

NeoPod_5/24/25

DATASHEETS AND REPOSITORIES I AM USING NOW - GY-PCM5102a - PCM5102a - ESP32-WROOM32 - kiswitch - KiCad Keyswitch Footprints

TIME SPENT: 6hrs

MAY 25, 2025

KICAD SKETCH

I've researched how switches are connected in keyboards and have connected them to one GPIO each. I have also added two USB-C receptacles for charging, serial debugging, and data transfer. The RP2040 is added. For the screen, I will use a 2.2" TFT ILI9341. Added the STC4054GR and a linear regulator XC6210B332MR, wired the switches together, wired everything together. I am now down with the schematic, assuming none of the wiring is wrong. YAY

NeoPod_5/25/25

DATASHEETS AND REPOSITORIES I AM USING NOW - RP2040 Pinout - Another RP2040 Pinout - Audiojack - scottokeebs kicad keyboard libraries - SN74CB3Q3257DBQR Datasheet

TIME SPENT: 6hrs

MAY 26, 2025

KICAD SKETCH

I finalized the connections based off of the ERC in kicad. I then put x indicators on all the pins that I would not be connecting to in order to avoid confusion. I realized that some of the digital ground pins were labelled with analog ground. So, I replaced all of the wrong ones.

NeoPod_5/26/25

KICAD PCB LAYOUT

Today I figured out the dimensions of the pcb. I am aiming for 100mm by 120mm so that the pcb can comfortably accomadate all the IC's I plan on putting on. I started the layout process by grouping the IC's together with all their components. Then, I placed the IC's that would stick out of the board such as the screen, USB-Cs, audio jack, and keyswitches so that I would know what space I had to work with in terms of trace and IC placement. I also started wiring and finished both USB-C plugs, some resistors and capacitors on the ESP32-WROOM32, and the DAC and audio jack. I did not finish the battery circuit, the SPI to UART converter, the RP2040 and microSD card reader, or the multiplexer.

NeoPod_pcb

TIME SPENT: 2hrs