使用5438的内部参考2.5v，测试ADC0的通道转换值，程序如下：
P6SEL |= BIT0; // P6.0 ADC option select
P5SEL |= 0x03;
ADC12CTL0 = ADC12SHT02 + ADC12ON + ADC12REFON + ADC12REF2_5V; // Sampling time = 64¸öADC12CLK,
ADC12CTL1 = ADC12SHP; // Use sampling timer,
ADC12CTL2 |= ADC12REFOUT;
ADC12MCTL0 = ADC12SREF_1;
for(usI = 0; usI < 0x30; usI++); // Delay for reference start-up
ADC12CTL0 |= ADC12ENC; // Enable conversions
while(1)
{
ADC12CTL0 |= ADC12SC; // Start sampling/conversion
while (0 == (ADC12IFG & BIT0));
__no_operation(); // For debugger #define _NOP() __no_operation()
}
按照我的设置P5.0/Vref引脚应该输出2.5v，但是现在0.4v
ADC0的输入电压为0.4v， ADC12MEM0 = 0x0FFF这是什么问题，请帮我分析一下
