10. Output devices¶
This week I worked on my output device for my final prject.
Weekly Objectives¶
- Group assignment:
- measure the power consumption of an output device
- Document your work on the group work page and reflect on your individual page what you learned
- Individual assignment:
- add an output device to a microcontroller board you’ve designed, and program it to do something
Useful links¶
Group Assignment and reflection¶
In this week group assignment, I found the power consumption of an OLED display. I learned how to use calculate power using voltage and current. I also learned how to use multimeter to measure the voltage and the amplitude of a circuit. The positive pen of the multimeter should be placed onto the VCC pin and the negative pen should be placed onto the GND pin.
You can find our full group documentation here.
Images on OLED Display¶
Since I have had some experience with OLED diaplay, I did not start with a Wokwi simulation. Instead, I went straight to the breadboard.
I first go on Google and found an awsome tutorial about displaying bitmap images on OLED screen. The tutorial used Arduino. I just converted the pins to XIAO RP2040 using the pinout.
Wiring Diagram¶
OLED Connection¶
| OLED Display Pin | XIAO RP2040 Pin |
|---|---|
| VCC | 5V |
| GND | GND |
| SDA | SDA (D4/GPIO6) |
| SCL | SCL (D5/GPIO7) |
Then I used the example code to test my screen. Here’s an image of the example code working.
Then I decided to add a switch to the circuit so that I could control the screen using a slide switch.
I used ChatGPT help me generate the code. Here’s a video of it working.
Creating my own image¶
After I used the example code to display a bitmap image onto the oled screen, I decided to create my own image. I used the website that the tutorial provides.
First,I found a really cute image of Miffy (the idea of Miffy was inspired by Angelina Yang because she is a big fan of Miffy).
Then I followed the instructions on the tutorial and then generated the bitmap gcode for the image.
However, I got this on my screen:
It did not show the whole image. After I double checked the settings and made sure that all the settings on the website wasthe same as the tutorial, I decided to figure out myself. I found out that the size of the canva shoud be 128x32 instead of 64 for my screen.
Then I changed the draw mode to “Horizontal-1 bit per pixel”.
Then I got this:
I decided to changed the draw code to “stretch to fill the canvas”.
Finally, I got a cute little intact Miffy on my oled screen!
Here’s a video of the whole circuit working:)
Final Code¶
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1 // Reset pin not used
#define SWITCH_PIN 28 // Slide switch connected to GPIO28
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
// Bitmap data (make sure to complete this with full data)
const unsigned char myBitmap[] PROGMEM = {
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};
void setup() {
pinMode(SWITCH_PIN, INPUT_PULLUP); // Use internal pull-up resistor
if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
while (true); // Halt if display is not found
}
display.clearDisplay();
display.display();
}
void loop() {
int switchState = digitalRead(SWITCH_PIN);
if (switchState == LOW) { // Switch ON (connected to GND)
display.ssd1306_command(SSD1306_DISPLAYON); // Turn display ON
display.clearDisplay();
display.drawBitmap(0, 0, myBitmap, SCREEN_WIDTH, SCREEN_HEIGHT, WHITE);
display.display();
} else { // Switch OFF (pull-up state)
display.ssd1306_command(SSD1306_DISPLAYOFF); // Turn display OFF
}
delay(100);
}
PCB Designing and Milling¶
After I built my circuit, I started to design my PCB board in Kicad.
I drew the diagram in the schematic editor.
Then I updated the PC and added wiring in the PCB editor.
This is a 3D view of my PCB board:
However, after I uploaded to into Bantam tool software, I found out that the traces were too close to each other, so I decided to redesign my PCB board.
This is the redesigned version of my PCB:
This is a 3D view of it:
Then I uploaded the drilling file and milled out my PCB board.
Soldering¶
After I milled out my PCb board, I started soldeing. This is the final look of my PCB board:
However, after I uploaded the code, what I got is this showed up on the screen.
Then the pins of the headers ripped off the traces, so I had to re-mill my PCB board.
Then I resoldered every components on and I was praying that this time it would work. Finally, after 4 hours of struggling, I finally made my board working!
Reflection of the Week¶
This week is pretty fun. I had some experience with the OLED display in our Electrical Engineering class last semester, so it was not that challenging for me. However, I did not explore the image aspect of the OLED display. But I successfully figured out how to display an bitmap image and milled a board for this week.
AI Usage¶
I used ChatGPT to help me generate the code and fixing my wiring. You can found the whole conversation here.
File Download¶
You can download my file here.