ATMEL9263 800*600屏驅動(dòng)問(wèn)題

后來(lái)查了一下代碼，問(wèn)題找到了，原因是改成大屏幕以后，LCD的象素時(shí)鐘變大，應用官方提供的代碼就出現問(wèn)題了。

//------------------------------------------------------------------------------
/// 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;
}

當應用大屏幕的時(shí)候，后面的表達式算出來(lái)是一個(gè)負數，所以時(shí)鐘送不出來(lái)，LCD也就驅動(dòng)不起來(lái)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);
}

}
參考數據手冊L(fǎng)CD寄存器描述，可以清楚的明白

BYPASS描述：

0 LCD象素時(shí)鐘 是由LCD控制器時(shí)鐘 根據CLKVAL分頻得到

1 LCD象素時(shí)鐘 就是LCD控制器時(shí)鐘