Final Project Development¶
This page outlines my Final Project development process.
1. Planning¶
1.1 The Requirements¶
These were my initial list of requirements and potential design approaches.
- The basic idea: a Portable shelf onto which original sockets can be attached and tested for connection.
- Ability to compare at least 2 scenarios; plugging in from the side, and down from the top.
- Size and number of sockets will be variable: so my main Circuit Board will be kept simple, and tiny boards will be added on for each Attachable Sockets.
- The Attachable socket also needs an LED to signal successful connection; this will be the programmable-LED type, which only needs one line.
- Made with Wood (MDF), so it will blend in naturally in a home environment for testing with actual users.
1.2 Overall Design¶
This is the basic Architecture.
This was the initial sketch.
I decided the length to be around 18 cm; to house 6-7 connector sockets of 2.5-3cm wide; enough to compare many options, but still relatively small and portable.
2. The Electronics¶
I drew a a basic circuit before getting into PCB design.
This is before factoring in circuit protection measures.
2.1 Main Circuit Board¶
I designed the Circuit Schematic and PCB layout on KiCad. My goal was to keep the board as small as possible.
Since I will be using the back-pad of the Xiao, I decided to flip the footprint so that the Xiao could be plugged in from the back of the PCB.
The circuits were milled onto Copper sheets at FabLab Kamakura.
I was also hoping to design a protecting casing with Acrylic, to protect the pins from accidental Short Circuits.
2.2 Tiny Circuit Boards for Attachable Sockets¶
Since I had very limited access to the Milling Machines at Fablab Kamakura, I experimented with fabricating Voltage Divider circuits using standard Pin Headers.
I tried a few different prototypes.
In the end I settled on this prototype which is simple to fabricate and can attach securely attachable to a wire-rack.
This will keep the wiring organized and the circuits safe from accidental Short-Circuits.
They unexpectedly turned out looking quite cute, like little Ninjas!🥷
I later made a much simpler and integrated version, with additional components to protect my Microcontroller, such as Capacitors and Resistors.
But I didn’t have the time to follow through with calculating the appropriate values.
3. The Exterior¶
Since CNC machines were not easily accessible, I decided to use layers of Laser-cut MDF sheets.
3.1 Shelf¶
All the modeling was done on Fusion 360.
Then Laser-cut them, and assembled them.
I spent unexpectedly long time working on the top board; I didn’t like how the different layers showed through, so I tried to smooth it with glue mixed with saw dust. But the MDF absorbed the glue which changed the color making it even more ugly! In the end, I fixed it by covering it with a thin pice of wood.
I also added a base for extra stability.
3.2 Attachable Socket and Mystery Connector¶
For my first socket, I decided to go with standard off-the-shelf Type-A USB socket, in order to test that the System works as intended. I also designed a 3D printed case that fits around a Type-A USB connector and my mystery circuit.
Not visible here but I laser-engraved labels for the 4 programmable-LED pins.
4. Coding¶
I wrote and tested the AnalogRead part and LED part separately before integrating them into a Final If/else code.
The Code for LED was written with the help of this guide on Akizuki and this guide on Hokuto Electronic.
The Final Code:
int DIN_H = 0;
int DIN_L = 1;
int LED_MAX = 1;//Number of LEDs connected
int Potentiometer[] = {D2, D3}; //InputTag
const int numTags = sizeof Potentiometer / sizeof Potentiometer[0];
int TagValue[numTags];
void setup() {
pinMode(DIN_H, OUTPUT);
pinMode(DIN_L, OUTPUT);
LED_Init();
analogReadResolution(12);
Serial.begin(9600);
}
void loop() {
for (int j = 0; j < numTags; j++){
TagValue[j] = analogRead(Potentiometer[j]);
Serial.print(TagValue[j]);
Serial.print(",");
if(TagValue[j]<3500){
LED_Color_RGB(0x00,0x7f,0x00); //緑
LED_Set();
}else{
for(int n=0;n<LED_MAX;n++)
LED_Color_RGB(0x00,0x00,0x7f);
LED_Set();
}
}
}
//for(int n=0;n<LED_MAX;n++)
//LED_Color_RGB(0x7f,0x00,0x00); //赤
//LED_Set();
//delay(800);
//=========================================================//
// LED Initialise
//=========================================================//
void LED_Init() {
digitalWrite(DIN_H, LOW);
digitalWrite(DIN_L, HIGH);
delay(50);
}
//=========================================================//
// Send Set signals
//=========================================================//
void LED_Set() {
digitalWrite(DIN_H, LOW);
digitalWrite(DIN_L, HIGH);
delay(5);
}
//=========================================================//
// H1 signal
//=========================================================//
void LED_Hi_Bit() {
digitalWrite(DIN_H, HIGH);
digitalWrite(DIN_L, HIGH);
delayMicroseconds(5);
digitalWrite(DIN_H, LOW);
digitalWrite(DIN_L, HIGH);
delayMicroseconds(5);
}
//=========================================================//
// L0 signal
//=========================================================//
void LED_Low_Bit() {
digitalWrite(DIN_H, LOW);
digitalWrite(DIN_L, LOW);
delayMicroseconds(5);
digitalWrite(DIN_H, LOW);
digitalWrite(DIN_L, HIGH);
delayMicroseconds(5);
}
//=========================================================//
// Formula for converting RGB color for LED
//=========================================================//
void LED_Color_RGB(byte led_r, byte led_g, byte led_b) {
for (int k = 0; k <= 7; k++) { //青
if ((bitRead(led_b, 7 - k)) == 1) {
LED_Hi_Bit();
}
else {
LED_Low_Bit();
}
}
for (int k = 0; k <= 7; k++) { //緑
if ((bitRead(led_g, 7 - k)) == 1) {
LED_Hi_Bit();
}
else {
LED_Low_Bit();
}
}
for (int k = 0; k <= 7; k++) { //赤
if ((bitRead(led_r, 7 - k)) == 1) {
LED_Hi_Bit();
}
else {
LED_Low_Bit();
}
}
}
5. Assembly and Operation¶
I assembled and wired up all the components.
The dilemma: shortening the wires would have made it look cleaner but harder to assemble
And it works!