8. Electronics Production¶

group assignment:¶

characterize the design rules for your in-house PCB production process
submit a PCB design to a board house

Here’s my group assignment for this week.

individual assignment:¶

make and test a microcontroller development board that you designed
extra credit: make it with another process

3 steps are needed for the CNC machine to process the file, first use the 0.4MM milling head to remove the copper around the wires, then use the 0.8mm milling head to cut the internal holes, and lastly, use the 0.8mm milling head to cut the outline.

1. Convert the PCB file to *.png file¶

Add a border to the PCB file to ensure that the 3 later processed files are the same size.Only the top layer, panelized layers and multiple layers are shown.
Export PDF file of PCB from EASYEDA. Edit the top layer of the assembly drawing to export the same layer as in the PCB, formatted as white on black with 0 transparency.
PCB.PDF
Convert PDF to PNG in PS with 1000 resolution. Next in PS, select Image - Mode - Grayscale - Bitmap - Grayscale, then Fill Pattern. Converted the PCB PNG into 3 kinds of processed files in PS (traces, holes, outline), exported *.png.
Finally, import the 3 png images into PS and check them in layers to make sure the 3 files are machined to the correct size.

2. making circuit boards with a CNC machine¶

Setting up CNC machines. A detailed description of how to commission a CNC machine is given in Teamwork, which can be viewed by clicking on group assignment.
Take the 3 .PNG files you just made and set them to the correct .rml format at the mods site.
traces_002_.rml
holes_pcb.rml
outline_pcb.rml
Processing 3 times in order to create a PCB， first do the surface treatment, process the traces file, then make the internal holes, and finally cut the external outlines.
Use a tool with a flat top to loosen the PCB, and after carefully removing it, use a knife or other tool to make the copper wires smooth and clean, avoiding contact with neighboring wires.

3.Solder the circuit board.¶

Export material Bom,Confirm the specifications of the component. You can determine the resistance value of a chip resistor by the number on top of it. A resistor with a number of 100n is 100×10^(n), so you can calculate the resistance of 1002 is 100×10^(2)=10000Ω, and the resistance of 100Ω is 1000.
Apply a little bit of solder on the PCB, use the tweezers in your left hand to fix the correct component in the soldering position, and hold the heated soldering iron in your right hand to solder the tiny component.
（Remember to solder the smaller components first and the larger components last.）

4.Upload the program and test the PCB¶

Find File > Preferences and populate the Additional Boards Manager URLs with the following URL:https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

Additional Boards Manager URLs

Find Tools > Board > Boards Manager… , enter the keyword “esp32” in the search box and select the latest version of esp32 and install it , enter the keyword “esp32” in the search box, select the latest version of esp32 and install it.

arduino-esp32

Select your board and serial port, find Tools > Board > ESP32 Arduino and select “XIAO_ESP32C3”. The list of boards is a bit long and you need to scroll to the bottom to reach it.

XIAO_ESP32_board

Connect the XIAO ESP32C3 to your computer via a USB Type-C cable.Switch to Tools > Port and select the name of the connected XIAO ESP32C3 serial port. This may be COM3 or higher (COM1 and COM2 are usually reserved for hardware serial ports).
Uploading the program to the board

 int led = D4;

 void setup() {
  pinMode(led, OUTPUT);
 }

 void loop() {
  digitalWrite(led, HIGH);   
  delay(1000);               
  digitalWrite(led, LOW);    
  delay(1000);               
 }

This is the result of my circuit board.