efthymios-ks / avr-ssd1306 Goto Github PK

Hello,

I have a simple program that uses your library. It makes it very simple to display text and basic shapes, thank you for contributing this. Every once in a while it seems something writes all over the memory of my application with values like 0xff or 0x00.

I have some code that adjusts my internally managed X and Y offsets on a timer. So the displayed image is shifted by a few pixels all over the screen very slowly. This is meant to avoid burn in of the display.

I have been trying to understand this problem and was doing some basic code review of your code and noticed what seems like an error in your Y Axis bounds checking

void GLCD_GotoX(const uint8_t X)
{
	if (X < __GLCD_Screen_Width)
		__GLCD.X = X;
}

void GLCD_GotoY(const uint8_t Y)
{
	if (__GLCD.Y < __GLCD_Screen_Height)
		__GLCD.Y = Y;
}

My screen height and width are less than 255.

If I make a call like GLCD_GotoX(255) it will just do nothing.

But I call GLCD_GotoY(255) the first call checks the existing value __GLCD.Y against the maximum height. It then sets __GLCD.Y = 255. Now __GLCD.Y is stuck at too large of a value. Presumably now the graphics library is just writing all over the SRAM of my device.

I think the check in GLCD_GotoY should be if ( Y < __GLCD_ScreenHeight). Do you agree?

Eric

On SSD1396.c, getting warning in Microchip Studio 7, "extra tokens at end of #ifdef directive" on line 41
On SSD1396.c, getting error in Microchip Studio 7, "missing binary operator before token "("" on line 107
On TWI.c, getting error in Microchip Studio 7, "'F_CPU' undeclared (first use in this function)" on line 23