Optional OLED splash screen and fixed OLED i2c execution time saving

[infinityis]

• Enable display of QMK OLED splash screen to be optional, allowing reduction in program size
• Fixed OLED page addressing, and corrected i2c execution time saving method

Description

#define NO_LCD_SPLASH

The OLED splash screen initialization with QMK logo is pretty but takes up program memory bytes. This change makes the splash screen conditional based on a new config.h #define. If #define NO_LCD_SPLASH is used, the OLED buffer is initialized to {0}. Testing with a 128x32 OLED shows a program size reduction about 500 bytes (128*32/8 = 512 bytes)

OLED Page Addressing fix

Also, an error was found in the OLED buffer writing function. As per SSD1306 datasheet, page 30 the options for "Set Memory Addressing Mode" are:

00b  Horizontal Addressing Mode
01b  Vertical Addressing Mode
10b  Page Addressing Mode (RESET)

However, the memory mode was being set to 0x10, which is not a valid option. Based on the code in send_buffer(), it appears that the intent was to use Page Addressing Mode, but the code to save i2c execution time was not implemented correctly. As written, the page_addr != i will always evaluate to true (because no compatible OLED has 2k vertical pixels) so the page address gets rewritten each time, even when it does not need to be updated.

This fix sets the memory addressing to page addressing mode (setting it to 10b = 0x02 instead of 0x10) and modifies the send_buffer code to actually track whether the page address needs to be re-sent.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation (adding the optional #define NO_LCD_SPLASH)
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[infinityis]

To be precise, setting memory mode to 0x10 isn't completely invalid, because the 6 high bits are "don't care". The two LSBs end up setting the memory mode to Horizontal Addressing Mode. Both the way the memory mode is being assigned and the way the code in send_buffer was written suggest that the intent was to use page addressing mode, but the approach was abandoned, resulting the pointless evaluation of page_addr != I. Correcting the page addressing mode and updating page_addr makes it a useful check.

[stale]

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