Week 5: Electronics Design

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  • Individual assignment: use an EDA tool to design a development board to interact with an embedded microcontroller
  • Group assignment: Use the test equipment in your lab to observe the operation of a microcontroller circuit boardr


    • Process ✏️

    I used KiCad to design my development board. This week was a HUGE learning curve for me, and I know that I will continue to revisit this week for weeks to come.

    In short, here is a preview of my schematic and pinout. I used an RP2040 to measure heartrate sensor output from the MAX30102. Big centered image of project Using RP2040 to conect to i2C pins.
    Big centered image of project
    Ensuring that there is enough space between the microcontroller and pulsometer, and that the wires do the cross through the boards! I kicked off this project by investing in some research. As I started to make design decisions on my schematic, I reached out to our HTMAA teaching team. To tie everything back to my final project, I want to create a "smart sports bra" that measures heartrate, body temperature, acceleration, and velocity. Neil mentioned using the BNO085. So, for a few key thinking: I'll be using the RP2040 as a microcontroller. For the group project, we used the ESP32 as a microcontroller to blink a light. This was helpful to understand the microcontroller's capabilities.

    Individual Assignment:

    For my PCB (printable computing board) board, I want to be sure there is room for flexibility in the coming weeks as my final project may shift. This is a super new area for me. I have so much to learn!

    I reviewed our HTMAA syllabus resources in EDA (Electronic Design Automation), sketching, schematic entry, component placement, (auto)routing, simulation, fabrication, layers, angles, vias, power planes, ground pours, design rules, DRC (Design Rule check), ERC (Electrical Rule Check).

    After doing so, I know I want to include the following ESP32 and BNO085. I will connect unused pins to headers. In the future when I narrow down sensor choices, I can make a small board with the sensor and use some wire to connect it to my main board.

    ESP32: Followed using a KiCad tutorial I'm a bit stumpted because I am trying to import these schematic files into Eagle. I have been playing around in the Fusion electronics design feature.

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    BNO082: These schematics were made in Easy EDA
    The BNO connected to an external microcontroller via the I2C interface. It is essentially 3 sensors in one device: an advanced triaxial 16bit gyroscope, a versatile, leading edge triaxial 14bit accelerometer and a full performance geomagnetic senso.

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    Example BNO PCB Image from Open Source Hardware Lab

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    Group Assignment:

    Below is the Arduino code that we provided. Originally, we thought we could simply plug & play our LED into the breadboard; but, we ended up soldering the microcontroller so it could fit in the breadboard.

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    What does this code do?

  • pinMode(D5, OUTPUT); This line sets pin D5 as an output pin. We need to define the pin mode before you start using it. Here, OUTPUT means the pin will be used to output voltage.

  • digitalWrite(D5, HIGH); This line sets the voltage level on pin D5 to HIGH, or in other words, it sends 3.3V (in the case of the ESP32) to the pin. If an LED is connected to this pin (with a suitable resistor), this will turn the LED on.

  • delay(500); This line causes the ESP32 to wait for 500 milliseconds (or half a second). During this time, the pin remains in its current state (HIGH in this case).

  • digitalWrite(D5, LOW); This line sets the voltage level on pin D5 to LOW, or 0 volts, turning the LED off if it's connected to this pin.

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    Soldering the RP2040
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    Breadboard with microcontroller
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    LED On!

    Reflection 🤔

    This week's electornic's module includes a lot of growth & remains a work in progress for me. I have better understanding of electronics design and building PCB boards. Now, I need to take the actual steps into building it.

    Project Resources 🔗

    RP2040 Data Sheet

    How to Design an ESP32 PCB Board

    Link to KiCad files

    Build Custom ESP32 Boards From Scratch! | the Complete Guide to Designing Your Own ESP32-S3 and C3

    ESP32 Schematic

    BNO Quick Start Guide

    BNO085 Data Sheet

    BNO085 Module Example Schematic & PCB

    Ani HTMAA Page: Ani’s HTMAA Page was super helpful in my learning process. She kept a vectorized image of Neil's face on an adjacent screen to give her a relative idea of where the components should go. This whole time I’ve been confused how everyone is laying their board’s on Neil’s face, but it became clear it’s just the layout and the circuit routing.