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[讨论] 温湿度+LCD12864学习中，湿度显示问题

正在学习用温湿度传感器将温湿度显示在LCD12864上。代码执行过程中，温度能显示正常，可湿度总是显示为0。

若将

<span style="background-color: rgb(247, 247, 247);">if(millis() - tepTimer > 500){</span>
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用delay(500);方法代替，则温湿度都能显示正常。请问这是怎么回事啊？不科学啊！！！

程序代码如下：

#include <dht11.h>
#include <LCD12864RSPI.h>
#define AR_SIZE( a ) sizeof( a ) / sizeof( a[0] )

unsigned long tepTimer;
unsigned char tempTitle[] = {0xCE,0xC2,0xB6,0xC8};//温度
unsigned char humiTitle[] = {0xCA,0xAA,0xB6,0xC8};//湿度
unsigned char line11[] = ":";
dht11 DHT;

void setup(){
  LCDA.initDriverPin(2,7,10);
  LCDA.Initialise();
  delay(100);
}

void loop(){
  int chk = DHT.read(4);
  int tempdata;
  int humidata;
  tempdata = DHT.temperature;
  humidata = DHT.humidity;

  if(millis() - tepTimer > 500){
    tepTimer = millis();
 
    LCDA.CLEAR();
    LCDA.DisplayString(0,0,tempTitle,AR_SIZE(tempTitle));
    LCDA.DisplayString(0,2,line11,AR_SIZE(line11));
    shownum(tempdata,0,3,2,0);
    LCDA.DisplayString(1,0,humiTitle,AR_SIZE(humiTitle));
    LCDA.DisplayString(1,2,line11,AR_SIZE(line11));
    shownum(humidata,1,3,2,0);
  }
}

void shownum(long num, int x, int y, int zlen, int xlen){
  char str[zlen];
  dtostrf(num,zlen,xlen,str);
  LCDA.DisplayString(x,y,(unsigned char *)str,AR_SIZE(str));
}
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