Group Assignment

Characterize the design rules for your in-house PCB production process

Please for group assignment details visit Anderson Zelarayan Web Page.

Individual Assignment

PCB Board

I select to do something similar to the PBC develop by Adrian Torres and use Module XIAO RP2040 as a starting point to fabricate a basic board to interact and communicate with a push bottom and a LED. And thinking on my final projet I added 8 pins that could act in future as Inputs or Outputs. The electronic components included are listed as follow:

  • 01 Seeed Studio Xiao RP2040.
  • 01 1kΩ resistor
  • 01 499 Ω resistor
  • 01 LED 1206
  • 01 SW - Button >
  • 01 Female horizontal row header
  • 01 100 μf capacitor

PCB and CNC Machine Setting

The machining was made with a Modela MDX-20 in two parts. First traces using 1/64¨ y secondly cutting the edges using 1/32¨ end mills.
We need a FR1 PCB board in this case we have available Copper Clad - Double Sided 4x6in. To set and mill it on the CNC machine we proceed as follow:

  1. Set double-sided tape into one side of the PCB (See fig a)
  2. Hold the FR1 board with double-sided tape into the machine, to avoid loosing the end-mill we set the PCB on X-Y plane orientation, starting at (10,10) coordinates (See fig b).

  3. Set power-off to introduce the end-mill, use a Hex Key to free the Grub Screw

  4. In this case for Paths you need to use a 1/64". It is recommendable to introduce 2/3 endmill's length into the machine endmill holder, to avoid failures and broke the endmill.

  5. We need to open the FabModules Sotfware, this module work with linux, thus we work with a laptop that only contain that system.
  6. OpenMods CE Software.

  7. Click Open Program that will appear listed on a light blue window.
  8. Look for Roland Brand and Select MDX mill PCBthat will appear listed down Roland machine.

  9. On the CNC press view bottom, the end mill will move to (o,o) coordinates
  10. Then we need to move the endmill to the PCB origin (10,10) using FabModules

  11. I proceeded with the zero calibration on the z-axis, to do that the machine has two bottoms. " UP" and "DOWN" , you've need to hold the down bottom, and the endmill will drill down faster and stop when your are near to the PCB

  12. Then, you need to press down bottom little by little, the endmill will drill down slower, until you'll see that the endmill release some cooper

    13. The following photo shows the final result after milling traces
  13. Yopu repeat this process with the 1/32" endmill to cut the PCB
This video shows the 1/64" milling process (traces)

This video shows the 1/32" milling process (cutting)

PCB Soldering

It was my first time soldering, so I didn't remove the double contact tape, and used to attach the PCB to the Soldering Mat Silicone (Heat Resistant), trying to avoid any movement while soldering. However it is recommendable to use the following soldering accesories to better handle the process

  1. Helping Hand with Magnifying Glass
  2. Electronic Work Center
  3. Magnifying Glass Soldering Stand with LED light

For the soldering process my instructor suggest me to star with smaller componebts

  1. I started soldering the resistors and LED
  2. The strategy was to fix one side (pin) of each component and then the others
  3. To proceed, first we can heat the PCB on the pin's area and deposit a small amount of soldering wire
  4. Then, took the component with a soldering tong and heat the area again
  5. The first side would be attched, and then easily you could do the other side, without using soldering tongs
    The following video shows the soldering process

  6. Then, I soldered the buttomand the pin headers.
  7. Here I must highlight that the seed estudio XIAO RP2040 require to solder pin headers, to being able to attached to the PCB. I soldered 2 1x7 M-M vertical pin headers to each side
  8. Within the PCB I soldered 2 1x7 F-M vertical pin headers at each side to receive the XIAO

The following photo shows the final PCB soldered result

PCB Testing

The testing process was undertake in two steps:

  1. First PBC testing with the multimeter aim to look for potential problems with the soldering process. Here we ensure that only ground traces produced sound during testing
  2. The funtioning test was made with basic programing using ArduinoIDE. To do that we need first to prepare the Arduino IDE to work with XIAO RP2040
  3. We need to add Seeed Studio XIAO RP2040 board package to Arduino IDE's preferences (See photo).
  4. Like recomended on Seeed Studio installing earlephilhower package.

  5. We need to go to Board Manager and install Raspberry Pi Pico/RP2040.
  6. Then, we need to click on Tools, board board manager. In that way Arduino IDE will recognise the XIAO RP2040

  7. We need to wrote a small program in Arduino to test the board. I decided to develop a simple program to turn LED on and off, but using push buttom.
  8. I use chat GPT to get a basic coding using the following prompt: "could you provide me a code to use it on arduino IDE that allows me to control a LED with a push buttom using a XIAO RP2040 as a control board"

    9. 
	// Define pin numbers
	const int buttonPin = D1; // the number of the pushbutton pin
	const int ledPin =  D0;  // the number of the LED pin
	
	// Variables will change:
	int buttonState = 0; // variable for reading the pushbutton status
	
	void setup() {
	  // Initialize the LED pin as an output:
	  pinMode(ledPin, OUTPUT);
	  // Initialize the pushbutton pin as an input with internal pull-up resistor:
	  pinMode(buttonPin, INPUT_PULLUP);
	}
	
	void loop() {
	  // Read the state of the pushbutton value:
	  buttonState = digitalRead(buttonPin);
	
	  // Check if the pushbutton is pressed.
	  // If it is, the buttonState is LOW:
	  if (buttonState == LOW) {
		// Turn LED on:
		digitalWrite(ledPin, HIGH);
	  } else {
		// Turn LED off:
		digitalWrite(ledPin, LOW);
	  }
	}
  9. At the begining the "const int buttonPin = D1" assign the number of the pushbutton pin and the "const int ledPin = D0" define the number of the LED pin. This assign correspond to the following Pinout


  10. The "void setup" is a function that contains the initialization of the two components that I want to control (input=Push Button and output=LED)
  11. "pin mode", will configure the pin DO to behave either as an ouput (LED) and D1 as an input (Push Buttom)
  12. "void loop" allows to repeat your code over and over again, that is why we need to add here the "buttonState = digitalRead(buttonPin)" (input D1)
  13. Then, we need will set a HIGH or a LOW value to output digital pin, in this case pin DO (LED Connection). Because the pin has been configured as an OUTPUT with pinMode(),its voltage was set to receiving 5V - 3.3V, being in HIGH mode (turn LED on) when the buttom is not pushed (buttonState == LOW)
  14. And it will receive 0V (ground) being in LOW mode (turn LED off) when the buttom is pushed (buttonState == HIGH)
  15. We need to upload the codeinto the XIAO RP2040 by clicking upload buttom on Arduino IDE, the program will be upload on XIAO RP2040
  16. Then, we just need to tried if the program runs, like shown in the folowing video
  17. run the program and check for LED lightining like shown in the video below
    18. The following video shows how the led goes on and on when pushing the buttom

You can get access to the SVG files here.

You can get access to the Arduino code here.

Reflections

  1. The FabModules program need to be set at 1000 dpi, otherwise the PCB will be milling width traces thouching each other
  2. The endmills need to be introduce 2/3 of their length to avoid being loose and broke
  3. The milling process needs to be undertake with atention con establishing correct coordinates
  4. Soldering process could be challenging, but if you use some soldering accesories, it could turn manageable
  5. ChatGPT could support the code developing, however you need to understand coding stages, so you can get the correct functioning