Mikroelektronika MIKROE-350 データシート

The OneWire library provides routines for communication via the Dallas OneWire
protocol, e.g. with DS18x20 digital thermometer. OneWire is a Master/Slave proto-
col, and all communication cabling required is a single wire. OneWire enabled
devices should have open collector drivers (with single pull-up resistor) on the
shared data line.

Slave devices on the OneWire bus can even get their power supply from data line.
For detailed schematic see device datasheet.

Some basic characteristics of this protocol are:

- single master system, 
- low cost, 
- low transfer rates (up to 16 kbps), 
- fairly long distances (up to 300 meters), 
- small data transfer packages. 

Each OneWire device has also a unique 64-bit registration number (8-bit device
type, 48-bit serial number and 8-bit CRC), so multiple slaves can co-exist on the
same bus.

Note: Oscillator frequency Fosc needs to be at least 8MHz in order to use the rou-
tines with Dallas digital thermometers.

- Ow_Reset 
- Ow_Read 
- Ow_Write 

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 6

dim OW_Bit_Read as
sbit sfr external

OneWire read line.

dim OW_Bit_Read as
sbit at PINB.B2

dim OW_Bit_Write as
sbit sfr external

OneWire write line.

dim OW_Bit_Write as
sbit at PORTB.B2

dim OW_Bit_Direction
as sbit sfr external

Direction of the OneWire pin.

dim OW_Bit_Direction
as sbit at DDRB.B2