# OLED SSD1306 Linux driver
This is plain c code using linux I2C device node (/dev/i2c-X X for 0,1,2,3...).
Please make sure the linux has run "modprobe i2c-dev".
128x64 and 128x32 are supporting and using I2C interface ONLY
## Files
**linux_i2c.c** source code for i2c control in linux device node.
**linux_i2c.h** header file for i2c control in linux.
**ssd1306.c** i2c protocol functions to control oled SSD1306.
**ssd1306.h** header file for i2c protocol functions and defined commands in SSD1306.
**font.h** font header file define 5x7 small font and 8x8 normal font. ascii value from 0x20(SPACE) to 0x7e(~).
**main.c** main file to take params and control oled SSD1306.
**Makefile** plain Makefile to build the source code. It works in raspberry pi.
**Readme.md** this readme file.
## How to compile
Require make and gcc. If you use cross compile, please self define $(CC).
Type "make" to build binary "ssd1306_bin".
Type "make clean" to clean the project.
## How to use
- always init oled module ONCE when power up.
- set the device node address EVERYTIME if not using default value /dev/i2c-0
- the init oled module always reset XY cursor to (0,0)
- all params can set together
- clear screen if new text need to write, otherwise wording overlapping happened
- resolution value stored in /tmp/.ssd1306_oled_type with format like "128x64" or "128x32" or "64x48"
- always do display rotation first and then filling text. otherwise the text cause mirror
- make sure the XY cursor setting in correct location before printing text
### Params
```sh
-I		init oled (128x32 or 128x64 or 64x48)
-c		clear (line number or all)
-d		0/display off 1/display on
-f      0/small font 5x7 1/normal font 8x8 (default small font)
-h		help message
-i		0/normal oled 1/invert oled
-l		put your line to display
-m		put your strings to oled
-n      I2C device node address (0,1,2..., default 0)
-r		0/normal 180/rotate
-x		x position
-y 		y position
```
## Example
### init the OLED once
- resolution 128x64
```sh
$ ./ssd1306_bin -I 128x64
```
- resolution 128x32
```sh
$ ./ssd1306_bin -I 128x32
```
- resolution 64x48
```sh
$ ./ssd1306_bin -I 64x48
```
### clear display
- clear 1st line
```sh
./ssd1306_bin -c0
```
- clear 2nd line
```sh
$ ./ssd1306_bin -c1
```
- clear 4th line
```sh
$ ./ssd1306_bin -c3
```
- clear whole screen
```sh
$ ./ssd1306_bin -c
```
### display on/off
- turn off display
```sh
$ ./ssd1306_bin -d 0
```
- turn on display
```sh
$ ./ssd1306_bin -d 1
```
### inverting display
- normal oled (0 is off, 1 is on)
```sh
$ ./ssd1306_bin -i 0
```
- invert oled (0 is on, 1 is off)
```sh
$ ./ssd1306_bin -i 1
```
### print words
- write line "Hello World"
```sh
$ ./ssd1306_bin -l "Hello World"
```
- write message "alpha\nbravo\ncharlie\ndelta" (please place \n for next line)
```sh
$ ./ssd1306_bin -m "alpha\nbravo\ncharlie\ndelta"
```
### I2C device address (default is /dev/i2c-0)
- using /dev/i2c-1
```sh
$ ./ssd1306_bin -n 1
```
### rotate display
- normal orientation
```sh
$ ./ssd1306_bin -r 0
```
- turn 180 orientation
```sh
$ ./ssd1306_bin -r 180
```
### set cursor location
- set XY cursor 8,1(x is column, 8 columns skipping, y is row, 2nd line)
```sh
$ ./ssd1306_bin -x 8 -y 1
```