#include <stdio.h>#include <wiringPi.h>#include <pcf8591.h>#define PCF 120int main (void){ int value ; wiringPiSetup () ; // Setup pcf8591 on base pin 120, and address 0x48 pcf8591Setup (PCF, 0x48) ; while(1) // loop forever { value = analogRead (PCF + 3) ; printf("%d\n", value); analogWrite (PCF + 0, value) ; delay (10) ; } return 0 ;}大佬们我想问一下这个pcf为什么是120吗？不应该是控制字0x40吗？