ACQT和ADCS值怎么选择

大家好，芯片是PIC18F46K22，40引脚DIP封装，我使用的是外部XTAL OSC。我用它的ADC读取一个在它的通道0上连接的模拟信号。我已经阅读了数据表，在ADC中有2个参数，虽然我的ADC代码工作正常，但是我仍然关注以下2个参数。1）ACQT-A/D如果系统时钟是20 MHz外部晶体，那么我应该选择上述参数的值吗？我应该为上面的参数选择高值还是低值？我的代码是附加在下面的建议。任何帮助都非常感谢。



      以下为原文

    Hello everyone
My chip is PIC18F46K22, 40 pins DIP package, and i am using external XTAL Osc. of 20MHz.

I am using its ADC to read an analog signal that is connected on its channel 0.
I have read the datasheet and there are 2 parameters in ADC that i could not make sense of although my ADC code is working as expected but still i am concerned about the following 2 parameters.
1) ACQT - A/D Acquisition time select bits
2) ADCS - A/D Conversion Clock Select bits

How should i select the values of above parameters if my system clock is 20 MHz external crystal?
Should i select a high value or a low value for the above parameters?

My code is appended below for suggestions.

Any help is highly appreciated.

void setup_routine()
{
...
TRISAbits.TRISA0=1; //AN0
/*Vref+ = VDD, Vref- = VSS.*/
ADCON1bits.NVCFG0 = 0;
ADCON1bits.NVCFG1 = 0;
ADCON1bits.PVCFG0 = 0;
ADCON1bits.PVCFG1 = 0;
ADCS0 = 0;
ADCS1 = 1;
ADCS2 = 1;
ADON = 1; // ADC in turned ON
...
}


void ADC_data()
{
unsigned char acquisitiontime=100;
...
ADCChannel_0();
ADFM = 0; // left justified

while(acquisitiontime--);

GODONE=1;
while(GODONE==1);
adcvalue = ADRESH;
// only required to read high byte and ignore low byte.
...
}