1. The newly edited program cannot read the temperature.
1. Confirm that the pin order is correct.
As shown in the figure, the pin order of the sensor in the T092 package is VDD, DQ, GND, as indicated in the figure.
The pinout of the TO92S packaged sensor is shown in the figure. For other packages, please refer to the documentation.
2. Confirm that the external circuit is correct.
A pull-up resistor is required at the DQ terminal of the sensor, and 100nF capacitors are required at the VDD and GND terminals. A strong drive circuit is required when using the sensor at multiple points or over long distances.
3. Conversion time
The GX18B20 sensor requires 750ms to convert temperature data, so you need to wait 750ms after sending the conversion command before reading the temperature.
4. Programming issues
When editing a program, it is recommended to use an oscilloscope to observe the waveforms and to edit the program in conjunction with the timing information in the documentation.
II. Temperature cannot be read after the chip is replaced with GX18B20.
1. Check if the chip is damaged.
Use a multimeter to check if the diode is present at the pin; the normal reading is around 0.5.
2. Observe the chip silkscreen.
The GX18B20 sensor is currently available in D02 and D03 versions. If the D03 version chip fails to measure temperature properly, please check whether the main control I0 switches to input mode when detecting the chip reset signal in the program. See the image below:
The D03 version chip has reduced power consumption, which weakens the pin driving capability. The sensor can only successfully pull the IO port low when the IO is set to input mode. The D02 version does not have this problem.
III. The chip cannot be read after processing or using it for a period of time.
If the chip cannot be read after being processed into a product or after a period of use, a multimeter can be used to check whether the chip diode is normal. Due to its shape and structure, static electricity can easily enter the GX18B20 sensor and damage its internal structure. Therefore, anti-static protection is required during the processing. For long-distance and multi-point applications, a surge protection module should be added at the end.
IV. Unstable reading performance in multi-point, long-distance applications
1. Check for any chip damage.
When encountering unstable readings in multi-point, long-distance applications, the first step should be to rule out the possibility of damaged chips or diodes. Therefore, it is best to use multiple cables spliced together for multi-point, long-distance applications to facilitate troubleshooting. If no chip damage is confirmed, try using enhanced drivers and adjusting timings to resolve the issue. If necessary, consider replacing the sensor with our more stable version, GX1831.
2. Confirm whether there is any external interference.
Interference may occur if a high-power motor is used near the GX18B20 sensor or its corresponding data acquisition unit, or if the GX18B20 cable runs parallel to the power cord for a long distance. Try keeping the cable away from the power cord or motor and using a separate power supply to resolve this issue.
5. Chip readout temperature is too high
All chips undergo testing after leaving the factory, and temperature errors are within the range specified in the documentation. If the reading temperature is significantly higher than normal, check for heat sources around the chip, such as voltage regulator chips or LCD screens. Additionally, the chip may also overheat if the diode exhibits weak breakdown (diode test values are approximately 0.5 mm below normal, indicating it is not completely broken down).
