How to write a low resolution and slow interface display panel driver

Applicable for

STM32MP13x lines, STM32MP15x lines, STM32MP25x lines

1. Article purpose[edit source]

Low resolution display panels can be connected to STM32 boards using low speed interfaces like I2C, SPI or FMC. Some famous of this category of display panels are:

the SSD1306 monochrome OLED panels,
the GC9A01 round 16-bit color panels,
the 1602 monochrome 2 text lines panels.

The purpose of this article is to:

briefly describe the main characteristics of the low resolution panels,
present some hardware attention points to consider before writing a panel software driver,
introduce the Linux^® kernel frameworks used to control these display panels,
describe how to write, test and debug your own display panel driver,
demonstrate simple use cases based on these display panels,
suggest alternatives for driving these display panels.

{{Info | Before you continue reading this article, you might be interested in the following articles: DRM KMS overview, How to write a display panel or bridge driver, I2C overview, [[SPI overview].}}

2. Prerequisites and preparations[edit source]

What is required to complete the following steps or to achieve the goal?

3. Hardware considerations[edit source]

4. Linux Kernel[edit source]

4.1. Architecture[edit source]

4.2. Software frameworks and drivers[edit source]

4.3. Tests and Debug[edit source]

4.4. Performance considerations[edit source]

5. Use case examples[edit source]

5.1. System monitoring[edit source]

5.2. Video playbacks[edit source]

5.3. Graphics with GPU[edit source]

6. Backlight[edit source]

7. U-boot[edit source]

8. Procedure 1[edit source]

Explain the outcome of this procedure. In the table below, list each high-level step which will be documented in detail below the table.

Step	What to do	Notes
1
2
3

8.1. Step-by-step instructions[edit source]

Do step 1
Do step 2
1. Do substep 2.1
Do step 3

9. Procedure 2[edit source]