OLED Screen Graphics (I2C)

OLED Screen Graphics

describe in one slide image vs canvas size

OLED screen consists of 64 (W) x 48 (H) pixels (3,072 total pixels)
3,072 pixels means 3,072 bits (ON or OFF) are needed to display a full image
- 3,072 bits is 384 bytes (8 bits = 1 byte)
Each pixel is either ON (HIGH) or OFF (LOW) because there is only one color
We can display images on the screen in a bitmap format

Original Image	Image Closeup to Show Pixels

Bitmaps are stored as large arrays of bytes
In a monochrome image, there is one bit per pixel
- 64 pixel x 48 pixel images = 3,072 bits = 384 bytes
Ex:

const uint8_t heart_bmp[] = { 
  0x00, 0x00, 0x00, 0x00, 
  0x00, 0x00, 0x00, 0x80, 
  0xe0, 0xf0, 0xf8, 0xfc, 
  ... }; 

Use a tool to convert image to byte array
Color Restrictions
- Each image to be converted should be black and white
- Color and greyscale can work but not well
Image Size
- Use small or actual size images for better conversion to bitmap
  Example Images

Original Black/White Image	Bitmap on OLED

Note
- The following settings are specific for the SparkFun Micro OLED
- Sparkfun library requires that each bitmap be specified as 64x48 pixels or 384 bytes (canvas size), even if parts of the image is blank
Image settings
- Canvas size: 64x48
- Glyph: blank
- Scaling: Scale fit, keeping proportions
Output
- Code output format: Arduino code, single bitmap (later in source change declaration to const uint8_t <PUT BITMAP NAME HERE> [])
- Draw mode: Vertical - 1 bit per pixel

const uint8_t heart_bmp[] = { 
  0x00, 0x00, 0x00, 0x00, 
  0x00, 0x00, 0x00, 0x80, 
  0xe0, 0xf0, 0xf8, 0xfc, 
  ... }; 

Convert itp348_full_screen.jpg to bitmap and load as startup graphic (image is in the starting folder)
Using the ultrasonic distance sensor, display graphics and distance measurement on the OLED
- Large error graphic when out of range (no_full_screen.png)
- Small warning message when less than 5 inches (warning_half_screen.png)
- Small graphics and distance message otherwise (yes_half_screen.png)
Bitmaps are provided in starting project folder