GX18B20 operates normally in industrial environment, but after a few hours, there will be a certain probability of abnormal reset, that is, no response signal, or read temperature value is not within the normal temperature range of PDF. If the 18B20 sensor is unplugged and plugged in or the device is re-energized, it will recover as usual, but it may occur after a period of time, and the specific reasons can not be found for a long time.
1. The lead of 18B20 is frequency-shielded and the outer skin is grounded.
2. Use timer to reset regularly.
Note:
GX18B20 for precise temperature conversion, I/O line must ensure that sufficient energy is provided during temperature conversion. Because the working current of each 18B20 during temperature conversion reaches 1 mA, when several temperature sensors are hung on the same I/O line for multi-point temperature measurement, only 4.7K pull-up resistance can not provide enough energy, which will result in the failure to convert temperature or temperature error.
This circuit is only suitable for single temperature sensor to measure temperature, and not suitable for battery power supply system. And the working power supply VCC must be guaranteed at 5V. When the power supply voltage drops, the parasitic power supply can absorb less energy, which will make the temperature error larger.
In addition, it should be noted that under the external power supply mode, the GND pin of 18B20 can not be suspended, otherwise the temperature can not be converted, and the reading temperature is always 85 degrees Celsius.
