用电脑Python控制Arduino

import serial #导入串口通讯库
import timeser=serial.Serial("com4",9600,timeout=1)
demo1=b""
demo2=b""
while 1:
c = input('请输入指令:')
if (c == ''):
ser.write(demo1)
if (c == ''):
ser.write(demo2)

void setup(){
Serial.begin();
pinMode(,OUTPUT);//设置13号端口作为输出端口
digitalWrite(,HIGH);
}
char var;
void loop(){
while(Serial.available()>)
{
var=Serial.read();
if(var == ''){
digitalWrite(,LOW);}
if(var== ''){
digitalWrite(,HIGH);}
}
}