JZ2440时钟
硬件上电选择时钟源:
时钟生成路线:
寄存器设置:
void clock_init()
{
LOCKTIME= 0xFFFFFFFF;
//CLKDIVN,FCLK= 400MHz,HCLK = FCLK / 4 = 100MHz,PCLK = HCLK / 2 = 50MHz
CLKDIVN = 0x5;
//MPLLCON,Mpll= (2 * m * Fin) / (p * 2^S),m = (MDIV + 8) = 92 + 8 = 100,
//p = (PDIV +2) = 1 + 2 = 3, s = SDIV = 1
//Mpll= (2 * 100 * 12MHz) / (3 * 2^1) = 400MHz
MPLLCON = ((92 << 12) | (1 << 4) | (1<< 0));
}