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1-Wire Communication Through Software

1-Wire Communication Through Software

A microprocessor can easily generate 1-Wire timing signals if a dedicated bus master is not present. This application note provides an example, written in C, of the basic standard speed 1-Wire master communication routines.
The four basic operations of a 1-Wire bus are Reset, Write 1 bit, Write 0 bit, and Read bit. The time it takes to perform one bit of communication is called a time slot in the device datasheets. Byte functions can then be derived from multiple calls to the bit operations. See Table 1 below for a brief description of each operation and a list of the steps necessary to generate it. Figure illustrates the waveforms graphically. Table 2 shows the minimum, maximum and recommended timings for the 1-Wire master to communicate with 1-Wire devices over the most common line conditions. Alternate minimum and maximum values can be used when restricting the 1-Wire master to a particular set of devices and line conditions.


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