maix dock＋18B20 长时间工作后就一直读4096

问题：工作半小时内没有问题，时间超出半小时后读值就卡在4095.73....了 就很迷惑...

from fpioa_manager import *
from modules import onewire
from board import board_info
import time
fm.register(14, fm.fpioa.GPIOHS2, force=True)
ds18b20=onewire(fm.fpioa.GPIOHS2)
def get_temp():
    ds18b20.reset()
    ds18b20.writebyte(0xcc)
    ds18b20.writebyte(0x44)
    ds18b20.reset()
    ds18b20.writebyte(0xcc)
    ds18b20.writebyte(0xbe)
    tplsb=ds18b20.readbyte()
    tpmsb=ds18b20.readbyte()
    s_tem = tpmsb<<8;
    s_tem = s_tem | tplsb;
    if( s_tem < 0 ):
        f_tem = (~s_tem+1) * 0.0625;
    else:
        f_tem = (s_tem * 0.0625);
    return f_tem
while(True):
    print(get_temp())