Please mention about the interface that you had used. Have you used any SDK example firmware to built this project?
Thanks & Regards
Yes, I have used the SDK example firmware, but I see the official routines are IO port as either input or output, not as a two-way IO port, you know DS18B20 needs to switch the input and output state to simulate the timing, so I don't know how to solve this problem.
There is no configuration which can make a GPIO as output and input simultaneously.
What can be tried is to call CyU3PGpioSetSimpleConfig() repeatedly in your firmware to change the configuration to input/output.