1. Initialization process: Every read should be initialized, otherwise 18B20 is in standby state and can not be read successfully.

2. Pull down the signal line 480-700us, reset it, release the bus 15-60us, 18B20 pulls down the bus 60-240us, and then it releases the bus. So one sign of successful initialization is whether you can read 18b20, a low-first-high operation sequence.

3. Write 1 bit data process: process 1 writes 0, process 2 writes 1. Procedure 1: Pull down bus 60us, then raise bus 5us, complete. Procedure 2: Pull down bus 5us, then raise bus 60us, finish

3. Reading 1 bit process: process 1 is reading 0, process 2 is reading 1. Procedure 1, 2: Pull down the bus 5us, then release the bus, read the bus, if 0, read in 0, if 1, read in 1.