https://orsoeric.github.io/2020-07-26-Longan-Screen-Class-Demo/main_8cpp.html
My objective for this project is to develop drivers for the Longan Nano evaluation board
I need a lightweight LCD screen driver that uses little CPU and print characters on the screen asynchronously
I need a time class to profile execution times and schedule tasks for the hardwired scheduler
I added a LED class to practice with C++ scoping and use of combined header and implementation since I use lots of inline, and inline functions and template functions need to be declared alongside the header anyway
With the latest update I added support for 10x8 "Courier Now" ascii sprites and 16x8 "NSimSun" ascii sprites as well with bug fixes and optimization
With 10x8 sprites there are 8x20 sprites on screen. With 16x8 sprites there are 5x20 sprites on screen
The Screen driver uses between 1.1% to 2.4% of the CPU when scheduled every 100us depending on workload
1 - clear screen to random color every 500ms
2 - print a character every 1ms
3 - print a colored character every 1ms
4 - print a string every 25ms
5 - print a colored string every 25ms
6 - print number on screen with reserved space and left/right adjust
7 - profiler with engineering number format, four significant digits and si suffix and time profiling and cpu usage of the demos
8 - Profiler with sprites pending counter
9 - Profiler with colors
10 - Constant workload demo with CPU profiler
Gif of the demo in action
Youtube video of the demo in action with brief explaination
The interrupts, clock system and DMA are more or less figured out
The driver for the LCD is divided in a Display class that handles the HAL, and a Screen class that handles the sprite based abstraction layer. This allows to massively reduce the bandwidth by not updating sprites already on screen and allow to hopefully change screen in the future without much trouble thanks to the ABI interface
The Chrono class allows to measure time using the integrated 64bit 27MHz SysTick timer, and allow to build an hardwired scheduler for my tasks
For the next step I'm going to build a template application I can start with for a fresh project
My first application will be the development of the motor controller for my OrangeBot robotic platform, with the aim of increasing the precision of the controls, and give an healthy amount of feedback on the screen, including voltage, power, currents, encoders, errors and more