onewire — Single Bus

Single bus is one-wire bus, which is the peripheral serial expansion bus technology launched by American DALLAS company. Different from SPI and I²C serial data communication methods. It uses a single signal line to transmit both clock and data, and the data transmission is bidirectional. It has many advantages such as saving I/O lines, simple resource structure, low cost, and easy bus expansion and maintenance.

The single bus is suitable for a single master system and can control one or more slave devices. The host can be a microcontroller, the slave can be a single bus device, the data exchange between them only through a signal line. When there is only one slave device, the system can operate as a single-node system; when there are multiple slave devices, the system operates as a multi-node system. Figure 12-1 shows a single bus multi-node system.

Schematic diagram of a single bus multi-node system

OneWire Class

class onewire.OneWire(pin)

Create OneWire class

• pin - machine.Pin instance object.

onewire.reset(required=False)

onewire.readinto(buf)

Read byte

onewire.write(buf)

Write byte

onewire.select_rom(rom)

onewire.scan()

Scan for devices on the bus

onewire.crc8(data)