105 lines
4.9 KiB
Markdown
105 lines
4.9 KiB
Markdown
|
|
[tocstart]: # (toc start)
|
|
|
|
* [RAM Optimization](#ram-optimization)
|
|
* [Flash Memory Optimization](#flash-memory-optimization)
|
|
* [Font Optimization](#font-optimization)
|
|
* [U8g2 Feature Selection](#u8g2-feature-selection)
|
|
|
|
[tocend]: # (toc end)
|
|
|
|
# RAM Optimization
|
|
|
|
On AVR systems, use the Arduino `F()` macro. U8g2 supports the Arduino `print`
|
|
function, which accepts the `F()` macro.
|
|
|
|
A simple example for the `F()` macro is available as an example:
|
|
|
|
[https://github.com/olikraus/u8g2/blob/master/sys/arduino/u8g2_page_buffer/PrintHelloWorld/PrintHelloWorld.ino](https://github.com/olikraus/u8g2/blob/master/sys/arduino/u8g2_page_buffer/PrintHelloWorld/PrintHelloWorld.ino)
|
|
|
|
A more complex example is here:
|
|
|
|
[https://github.com/olikraus/u8g2/blob/master/sys/arduino/u8g2_page_buffer/PrintProgmem/PrintProgmem.ino](https://github.com/olikraus/u8g2/blob/master/sys/arduino/u8g2_page_buffer/PrintProgmem/PrintProgmem.ino)
|
|
|
|
|
|
# Flash Memory Optimization
|
|
|
|
## Font Optimization
|
|
|
|
Usually U8g2 fonts are available in different sizes (number of glyphs included in the
|
|
font). The last letter of the font name indicates the character set (and the size)
|
|
of the fonts.
|
|
|
|
| Font Name | Character Set |
|
|
|-------------|-----------|
|
|
| u8g2_xxx_xe | Extended: Glyphs with unicode 32 to 701 are included in the font (v2.16.x will also include big ß) |
|
|
| u8g2_xxx_xf | Full: Glyphs with unicode 32 to 255 are included in the font |
|
|
| u8g2_xxx_xr | Restricted: Only characters from 32 to 127 are included |
|
|
| u8g2_xxx_xu | Uppercase: Numbers and uppercase letters |
|
|
| u8g2_xxx_xn | Numbers and some extra glyphs for date and time printing are included |
|
|
| u8g2_xxx_x_something | Special selection of glyphs. See the font picture for details. |
|
|
|
|
For example if only a number needs to be displayed with a font,
|
|
then the font should contain only numbers. In such a case, it is better to
|
|
select a `n` font to avoid the allocation of unneeded chars in the flash memory.
|
|
|
|
Each font picture also includes the number of bytes, occupied by the font in
|
|
flash memory (upper part of the picture, third line):
|
|
|
|
|
|
|
|
These pictures are available on the [font group](fntgrp) pages for each font.
|
|
|
|
If there is no proper set, you can always create your own custom font with
|
|
exactly those characters, which are required for your
|
|
project (see [FAQ](https://github.com/olikraus/u8g2/blob/master/doc/faq.txt))
|
|
|
|
See also: [setFont](u8g2reference#setfont)
|
|
|
|
## U8g2 Feature Selection
|
|
|
|
U8g2 includes many features and includes several speed optimization procedures.
|
|
Sometimes speed is not critical or some features are not required. In those
|
|
cases, the user can disable such features in [`u8g2.h`](https://github.com/olikraus/u8g2/blob/master/csrc/u8g2.h):
|
|
|
|
Search for `u8g2.h` on your local drive.
|
|
For the Arduino Environment, `u8g2.h` should be in the subfolder
|
|
`libraries/U8g2_Arduino/src/clib` of your Arduino custom library folder.
|
|
|
|
The location of this custom library folder might be different on operating system and Arduino IDE.
|
|
It might be `C:\Users\<name>\AppData\Local\Arduino15\` on Windows OS or
|
|
`~/Arduino/Libraries` for Unix based systems.
|
|
Some other pathes are mentioned [on the Arduino library hacking page](https://www.arduino.cc/en/hacking/libraries).
|
|
|
|
All features names start with `U8G2_WITH_`. A feature is enabled with a `#define` of
|
|
the feature name. It is disabled if the `#define` is put into comments.
|
|
|
|
| Feature Name | Description |
|
|
|-------------|-----------|
|
|
| `U8G2_WITH_HVLINE_SPEED_OPTIMIZATION` | Enables speed optimization for pixel buffer writes. |
|
|
| `U8G2_WITH_INTERSECTION` | Enables speed optimization by early intersection tests for high level graphics primitives. |
|
|
| `U8G2_WITH_CLIP_WINDOW_SUPPORT` | Enables support for a custom clip window. If disabled, clipping will happen only against the display boundaries. |
|
|
| `U8G2_WITH_FONT_ROTATION` | Enables string output to all four directions. If disabled, strings can be written only from left to right. |
|
|
| `U8G2_WITH_UNICODE` | Enables support for Unicode Basic Multilingual Plane. |
|
|
|
|
|
|
By default all the above features are enabled. The following table gives an idea on the
|
|
flash memory reduction, if one or more features are disabled:
|
|
|
|
| Flash | Reduction | Disabled Feature |
|
|
|----------|----------------|-------------|
|
|
| 8732 | | default, all features active |
|
|
| 8500 | -2.65% | no `U8G2_WITH_CLIP_WINDOW_SUPPORT` |
|
|
| 8316 | -4.76% | no `U8G2_WITH_FONT_ROTATION` |
|
|
| 8606 | -1.44% | no `U8G2_WITH_UNICODE` |
|
|
| 8692 | -0.45% | no `U8G2_WITH_INTERSECTION` |
|
|
| 8328 | -4.62% | no `U8G2_WITH_INTERSECTION` no `U8G2_WITH_CLIP_WINDOW_SUPPORT` |
|
|
| 8718 | -4.86% | no `U8G2_WITH_HVLINE_SPEED_OPTIMIZATION` |
|
|
| 8026 | -8.08% | no `U8G2_WITH_FONT_ROTATION` no `U8G2_WITH_INTERSECTION` no `U8G2_WITH_CLIP_WINDOW_SUPPORT` |
|
|
|
|
Numbers are derived from:
|
|
* Arduino 1.84, U8g2 2.23, Arduino Uno
|
|
* U8G2_SSD1306_128X64_NONAME_1_4W_HW_SPI
|
|
|
|
|