ATMEL9263 800*600屏驱动问题

后来查了一下代码，问题找到了，原因是改成大屏幕以后，LCD的象素时钟变大，应用官方提供的代码就出现问题了。

//------------------------------------------------------------------------------
/// Configures the internal clock of the LCD controller given the master clock of
/// the system and the desired pixel clock in MHz.
/// param masterClock Master clock frequency.
/// param pixelClock Pixel clock frequency.
//------------------------------------------------------------------------------
void LCD_SetPixelClock(unsigned int masterClock, unsigned int pixelClock)
{
AT91C_BASE_LCDC->LCDC_LCDCON1 = ((masterClock / (2 * pixelClock)) - 1) << 12;
}

当应用大屏幕的时候，后面的表达式算出来是一个负数，所以时钟送不出来，LCD也就驱动不起来了

修改以后：

void LCD_SetPixelClock(unsigned int masterClock, unsigned int pixelClock)
{
unsigned int value;
value = masterClock / pixelClock;

if (masterClock % pixelClock)
{
value++;
}

value = value/2;

if (!value)
AT91C_BASE_LCDC->LCDC_LCDCON1 = AT91C_LCDC_BYPASS;
else
{
value -= 1;
AT91C_BASE_LCDC->LCDC_LCDCON1 = (value << 12);
}

}
参考数据手册LCD寄存器描述，可以清楚的明白

BYPASS描述：

0 LCD象素时钟 是由LCD控制器时钟 根据CLKVAL分频得到

1 LCD象素时钟 就是LCD控制器时钟