Real-Time BART Display

Project Two hero image

Goal

I was conversing with my brother on projects I could make over the summer and my brother suggested making a transit display. And as he lives in San Franscisco and often uses the BART service I found myself wanting to make a mini transit arrival display for his station.

Hardware

  • 20x4 OLED Display being a very visually clean display.
  • A 5V to 3.3V logic converter for prototyping (I just used this one for the schematic).
  • NodeMCU based with a ESP8266 chip.

    • BART API

    The Bay Area Rapid Transit [BART] has an amazing site online where all you need to do is apply for a key and you get public access for real-time changes for their public transportation. As long as this applies for any other city this project is readibly adjustable to other places of public transportation.

    Firmware

    The main I2C communication between OLED and MCU were provided by the suppliers on their [website] and all of the code and everything else is posted on my github [Here].

    Prototype

    Following the connection rules given by the OLED supplier and adjusting pins for a ESP8266 as the supplier assumes for ESP32.

    Project Two photo 1

    This was the working prototype for the display.

    Schematic

    All of the PCB work was designed using KiCad. I referenced the NodeMCU [Repository] a lot for understanding the connections and the eventual layout of everything.

    Project Two photo 2

    This is the USBC 5V input. It uses two pull down resistors and two decoupling capacitors with no data pins.

    Project Two photo 3

    These are the female head pins connections connected through the NodeMCU.

    Project Two photo 4

    Thess are the female header pins mirrored to the OLED display.

    Project Two photo 5

    This converts the 3.3V ESP logic to the 5V OLED logic and vice-versa.

    PCB Design

    The basic design is two ground planes with everything routed in between as orderly and organized as I could.

    Project Two photo 6

    My final design for the PCB.

    Case Design

    Project Two photo 7

    A modeled design made in Onshape [Here].

    Demo

    This is the final working design in action.

    Overview

    Overall this project was a great learning experience whether it was designing a PCB in KiCAD for the first time, improving my modeling skills in CAD, or understanding and encoding a MCU through a ESP to display something on and OLED.

    Inspiration & Credit

    • This reddit post by u/fil1983 turned out a surprising and helpful find. Their suggestion of display was spot on and it gave me a lot of inspiration to do this project.
    • The BART GTFS Realtime publically gives out their transit data.
    • NodeMCU website with a lot of helpful info.
    • NodeMCU Github was amazing for making models in kicad and for general firmware.
    • This tutorial was great for understanding the proper usage of decoupling capacitors and pulldown resistors for a USB-TypeC.
    • The OLED Webpage contains datasheets, 3d models, an interfacing guide, and all the code needed to function on a ESP chip.
    • My greatest source of motivation when making this project has to be my brother. He helped me in doing most of the 3d Modeling CAD work and I would have never started this project without his suggestion.

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