Tasks Group Assignment Testing PCB Design V1 electric schematic puzz rob Issue Card

W6 - Electronics Design

Computer controlled cutting

Tasks

  • Group assignment:
    • ✔ Use the test equipment in your lab to observe the operation of a microcontroller circuit board
  • Individual assignment:
    • ✔ Use an EDA tool to design a development board that uses parts from the inventory to interact and communicate with an embedded microcontroller
    • Extra credit: try another design workflow
    • Extra credit: simulate your design
    • ✔ Extra credit: design a case around your design

Group assignment

We did it all together in the FAB Lab Node Ilmenau. Bene was kind enough to summarize our labs group assignment.

Conclusion:

  • Guidelines for using multimeters
    • Stay within the same measuring range setting of the manual multimeter
    • Always turn off/ disconnect power supply when changing the values to avoid voltage spikes.
    • Always start measuring the higher values and then go smaller.
    • The little hooks and crocodile tips rock!
    • In the RIGOL there are two GNDs for measuring: 1 for bigger amperage and one for lower amperage. Same rules for the measuring ranges apply.
  • Lab rules concerning small (or SMD) electronic components
    • Only remove one container at a time and return it in the exact same spot you got it from to avoid confusion.
    • Do not just remove the covering plastic foil but cut off whole package of SMD components always so it stays presentable.
    • When assembling components for soldering, print out the BOM and paste electronic components behind each entry to avoid mix-ups.
    • Only one person at a time removed SMD components from the containers to avoid confusion.
  1. Started by downloading and installing kicadFAB library
  2. Measured an Arduino Nano powered by computer USB port -> Results in table below.
    3. Power mode 3.3V output pin 5V output pin Vin pin
    Computer to USB 3.291V 4.71V 4.31V
  3. Measured Arduino Nano powered by a Laboratory DC Power Supply from GWINSTEK GPS-3303 and measured with a standard multimeter and the RIGOL DM3068. All went smoothly so we decided to measure for the minimum required Voltage. According to the datasheets, either 6 or 7V are the minimum Voltage. 12V is the maximum Voltage. We concluded that we agree with the datasheet.
    4. Input Voltage Output voltage
    12V 5.962V
    9V 5.092V
    6V 4.96V
    5.8V 4.78V

Measuring process: Connected one measuring probe to GND and the other to respective voltage pin. The measurements of the standard multimeter were pretty much the same as the ones from the RIGOL. Hence, in the table the more precise result will be displayed.

testingNanoInLab
Measuring output voltage Arduino Nano

While measuring we discovered some weird phenomena. This list also includes random information our instructor gave us.

  1. Brown out: when the microcontroller notices the voltage is too low it raises a flag. Some microcontrollers automatically make a failsafe when this flag is raised. Some microcontrollers can also be programmed to do sth else when this happens.
  2. Vin for some reason already has a voltage applied to it when we were powering the Nano from the computer. We did not figure out why.
  3. When designing PCBs: widen the pads and traces required for higher amperage and connect the components in parallel. The traces can become smaller the more parallel branches have already been fed.
  4. When designing PCBs: fragile signal connections always in series.

Test PCB board

Functions: blink an LED either on it's own (when button is pressed) or via the XIAO.# This is the Link to the website I found the original schematic from. I did change it a little bit to add a button and the Xiao. I had some old 555 timer chips laying around and wanted to use them.

Download files:

I found this tutorial incredibly good. I recommend watching it.

Process of preparation to create your own PCB:

  1. Make schematic like usual.
  2. Once done, make sure the footprint are available. It is possible to create your own but quite annoying.
  3. Close the schematic editor and open the PCB editor by clicking on the green icon.
    Menu selection Kicad from main page
  4. Click "tools-Update PCB from Schematic" and place components.
    Layout PCB Editor Kicad
  5. Select the "Edge.Cuts" in the appearance (purple menu).
  6. Draw a rectangle (black symbol) from the draw tool bar (green menu) and dimension it accordingly by double clicking on it.
  7. Organize the "ratsnest" (initial automatic placements of all components) in a way that the least possible amount of traces/ wires/ connections cross paths. The thin lines indicate which components belong together. There are tools for this, but manually is faster. Press "r"
  8. Start drawing traces by clicking on the blue symbol in the green menu until everything is connected.
  9. Optional: click on View-3D viewer (brown menu) to see how it will look like when produced.
    3D view of PCB board
  10. Export to gerber
    1. Select File (in brown menu) - Fabrication Outputs - Gerbers - Plot
    2. Generate Drill Files - Generate Drill File - Close
    3. Close PCB editor back to main page
    4. View - Browse Project Files; Zip into Archive all .gbr & .drl files you find
  11. Check gerber file: initial page - gerber viewer - File - Open ZIP File archive

Electric schematic puzzRob

Go to the final project page for more information and context.

More information on choosing components: BOM choosing components

Download files:

buildingBlockSchematic
General building block schematic V1

Process of designing schematic

  1. Prepped Kicad. Installed FAB library following this tutorial. (This is a bit tricky because knowing the exact location files on computer is necessary)
  2. Learned how to manage multiple sheets in Kicad for modular designing.
  3. Designing User Interaction module. Considered options:

    Main problem remains: 3A required to power 5 RGB LEDs. See Comparisons of solutions for more information why I eventually chose to go only with an RGB Arcade Button.

    Power consumption of other components:

  4. Power Management circuit and charging circuit:
    1. General information on power management
    2. The RFID modules require a constant 3.3V power supply with little to no noise. Input from a 1s battery=3.7V -> Linear Buck Converter
    3. Charging circuit. 2 ICs were recommended online: I choose the second option due to the recommendation of the protection IC.
    4. Looked for possible batteries: SONY MNCOO2 3.7V 3120mAh
    5. Due to the high cost and high power consumption of the LEDs, I decided to look for alternatives. I found the IC MC34063AP Information about this decision process
  5. Research on specific requirements in PCB production. Apart from the standard PCB milling production they can also be created with a Vinylcutter. Two approaches:
    • Use a conductive (copper) base and stick the not conductive layers on top. Not preferred due to environmental and socioeconomic impact.
    • Use a non conductive base and stick the conductive traces onn top. Example: Aluminia base and copper traces cut from copper foil. Example 2: PCBs on glass with copper traces. Src 1 Src 2
  6. Defining Pinout of Pico:

Additional footprints:

Datasheets:

Comparison: Kilobot

Current market leader due to small size and wide range of applications as well as ample development from Harvard University. Creators: Michael Rubenstein and Prof. Radhika Nagpal. Cost: 14€ per robot, Size: height= ~3cm; Diameter 3.3cm

Issue card

What I struggled with this week:

  1. Kicad neither had the components or the footprints. Solution: googled them and found them on Snapeda website for free. I also considered doing them myself but problem #2 deleted the initial design that I had made and I got fed up with it.
  2. Other sheets and sub sheets in kicad: when creating a new sheet (Ctrl+s) it will make you create 2 sheets. Haven't quite figured out what the second one is for yet. However, if the name is not changed and you use that page, it will overwrite whatever you did on a different sub sub page (Hence how I lost my custom design of the footprint component). Solution: Name that second sheet exactly like your first one. This will prevent the overwriting and if the second page ever comes to play, you will always know to what sub sketch it belongs.

What I learned in electronics design:

  • I understood how a datasheet is employed effectively thus not making me dependent on online tutorials to design circuit from here on.
  • Understood how to calculate values for components. Though they taught us in uni classes, it was a hole different thing applied to my ambitious final project.
  • Been reading about more efficient study modes.
  • Been studying Dutch for some reason.

What I want to improve on next week

  • Calm down and relax
  • Catch up with other weeks leftover work