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6.Electronics Design:

03-03-2021 | Jai Hanani

1. Objectives:

2.Group Assignment: use the test equipment in your lab to observe the operation of a microcontroller circuit board.

3.Individual Assignment:

• redraw an echo hello-world board, check the design rules, make it, and test it
• add (at least) a button and LED (with current-limiting resistor)
• check the design rules, make it, and test it

4. Files, Planning, Tools:

Files:

• Micky Van Zeijl's Documentation
• Echo Hello-World Board
• My Design

• Research about basic electronics.
• Download Eagle, Study its documentation, Design something basic
• Make a Hello-World FTDI board in Eagle
• Add some basic components to the design
• Fabricate it
• Program it

Tools:

• Roland Mill
• Autodesk Eagle Software
• Ofcourse, Fab Mods

5.Initial Stages:

1. Right off the bat, I started going through Micky's Documentaiton.
2. Some basic fact:There can be voltage without current passage.
3. Then, I went through Autodesk PCB Design/Placing/Routing documentation for an overview.
Autodesk Routing Overview Autodesk Component Placement Overview
4. VCC (Voltage Common Collector) is the higher voltage with respect to GND (ground).
5. VCC is the power input of a device
6. Capacitor vs Resistor: Can Capacitors Replace Resistors?
7. Purpose of the capacitor: Filtering the voltage fluctuations in the circuit.
8. Purpose of the Resistor: To guard against high voltage.
9. Some helpful hueristics: Think of Voltage as the velocity of the ball thrown upwards, Current as the mass of the ball, and air resistance/gravity as the resistance.
10. We were advised by our instructors to choose Autodesk Eagle, over KiCad, even though I preffered the latter. Thus, I downloaded Eagle.

6. Setting up Eagle, and designing the basic schematic:

1. Downloading Autodesk Eagle is straight-forward, you can go here for further instructions: Here


Standard eagle interface.

2. Download the components that are in standard-FabLab inventory for Autodesk Eagle from here.
3. Load the library up in Eagle.

4. Start choosing components.

5. Load up all the necessary components on the schematic, and connect them using 'net' command, accordingly.


'Net' command.



Arranging the components in a schematic.

6. Switch to Board.

7. The interface of Board:

8. The next task is tracing. It can be done, either manually or by autorouter.


Quick_Route_Airwire tool in Eagle



Autorouting workflow.

9. One more additional parameter to consider is DRC. Keeping in mind our milling machine, I set Clearance:16 mils, and Size:16 mills.

7. Replicating the ftdi.44 hello_world board:

1. My next task was to replicate this board: here

2. Components:
   • ATTiny44
   • Capacitor 1uF
   • Resistor 10k
   • XTAL resonator
   • FTDI 1X6
   • 2X3 ISP header
3. Choose all these components from previously-loaded Fab library from the library manager.
4. Place them in the schematic, accordingly.

5. Autoroute, thereafter.

8. Adding a LED&Switch:

1. Preliminarily, I consulted the ATTiny44 documentations
2. Then, I looked up some instructables to see where people placed LEDs on a ATTiny44 chip
https://www.instructables.com/Program-an-ATtiny44458485-with-Arduino/
3. Then, I added a LED, and a 0.5K resistor to the schematic, yet again from the aforementioned library.

4. I had to do 'net/delete/re-net' plenty times, before I could come up with a stable one.
5. Then, I readily switched to the board interface, without realizing their lies the hardest part.
6. I spent a whole day trying to route the components, both manually and autoroute.
7. There was atleast one net that I could not route, and I had to re-align the components in a better place, and try doing it again.
8. Upon my mentor's advice, I deleted the extra connections to newly added components, and tried auto-routing. It worked.

9. But, I encountered this:


ERC errors. Lost consistency.

10. Then, I had to go through an entire workflow of resolving this, which included exporting the 'Netscript' from the schematic, ripping up the existing board traces, and loading the 'netscript' file directly in the board interface, through SCR.
11. Consult this, if you encounter the same problem.
12. I auto-routed my board, afresh. It looked like it worked. Once I closed the auto-route window, there was still one net that wasn't routed. Some compromise had to be made.

13. I chose to reduce the minimum_width to 12 from 16.

14. It got routed. The board is connected.


Done.

15. I exported the board as a monochrome image with 2000 dpi.
16. I made a cut file too, and exported it, also, as a monochrome image with 2000 dpi.
17. Here are the final results:


The Mill File



The Cut File

9. Milling & Programming:

1. I replicated the milling process of Electronics Production week, as detailed here
2. Here is the result:

3. Soldered it up:

4. Next, Go to File >> Preferences in Arduino IDE
5. Paste this link in "https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json" Additional Board Manager URLs
6. In the Board Manager, Search for ATTiny44 and install it.
7. In Menu >> Tools, Select Board >> ATTiny24/44/84, Processor >> ATTiny84, Clock >> External 20MHz
8. I flashed it using ISP, I made in Electronics Production week.

9. There was some problem with the LED. The polarity was wrong. I corrected it.
10. The bulb was on, indefinitely.
11. It was, then, programmed to not light-up when the switch was pressed.


                
                     
void setup() {
    DDRA = (1 << PA2);//OUTPUT LED on PA2
  }
  
  void loop() {
    PORTA = (1 << PA2);//LED is ON
    delay(500);
    PORTA &= ~(1 << PA2);//LED is OFF
    delay(500);
  }
                
            

12. Video:

10. Auxillary Stuff:

1. Learning Morse code:
   • Morse Code Basics
   • 3WPM Morse Code Practice I
   • 3WPM Morse Code Practice II
2. Smartphone cameras can record IR light: https://www.businessinsider.in/latest/use-this-cool-phone-trick-to-see-a-color-humans-cant-see/articleshow/49050579.cms
3. We programmed Arduino Uno to output morse code using LED. No, we are planning to decode the said morse code using IR Led
4. The kind of sensors that a standard smartphone carries is mind-boggling: https://developer.android.com/guide/topics/sensors/sensors_overview
5. Using android in-built sensor to detect light fluctuations: https://play.google.com/store/apps/details?id=com.keuwl.lightsensorcounter

Group Assignment:

• Voltage
• Current
• Continuity
• Resistance
• Frequency
• Capacitance

• V AC Range: 600.0 V
• V DC Range: 600.0 V
• Ohms Range: 40.00 MΩ
• Capacitor: 100.0 μF
• Frequency: 100.0 kHz
• Size: 130 mm x 65 mm x 27mm

• 2/3/4 Independent Isolated Output
• 4 LED Display Sets: 3 digits after decimal point
• 1mV/1mA(GPD-2303D/GPD-3303S/GPD-4303S)
• 100mV/10mA(GPD-3303D)
• 4 Sets Save/Recall
• Output on/off
• Tracking Series and Parallel mode
• USB Standard Interface
• Labview driver

• 100 MHz bandwidth, 1 M Memory
• USB storage, RS232C & J45 interface
• 4000 point record length for each channel
• Multi-waveforms math, FFT Function
• Cursor & Track measurement
• Waveform Record & Recall, Trigger Mode for Edge, Video, Pulse Width, Slope & Alternate

• 0.1Hz to 25MHz with in 0.1Hz Resolution
• Sine, Square, Triangular, Noise and Arbitrary Waveform
• 1% ~ 99% adjustable duty cycle for Square Waveform
• Waveform Parameter Setting Through Numeric Keypad Entry & Knob Selection
• Amplitude, DC Offset and Other Key Setting Information Shown on the 3.5" LCD Screen Simultaneously
• AM/FM/FSK Modulation, Sweep, and Frequency Counter Functions (AFG-2100 only)
• PC Arbitrary Waveform Editing Software

• SCPI compatible
• Communicate via USB Interface, using included USB to TTL serial converter cable
• Compact size for bench use or rack mountable (2U x 1/2U size)
• Discrete Fault Indicator/Remote Inhibit (DFI/RI). Useful for turning multiple power supplies On/Off simultaneously
• Application Software for front panel emulation and simple test sequence generation included
• Sheathed banana plug terminals for safety