Mikroelektronika MIKROE-724 データシート

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mikoBasic PRO for dsPIC30/33 and PIC24

MikroElektronika

The OneWire library provides routines for communication via the Dallas OneWire protocol, e.g. with DS18x20 digital 

thermometer. OneWire is a Master/Slave protocol, 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 also has 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.

Important: 

- Oscillator frequency Fosc needs to be at least 4MHz in order to use the routines with Dallas digital thermometers. 

- This library implements time-based activities, so interrupts need to be disabled when using OneWire library. 

Library Routines

 

- Ow_Reset 

 

- Ow_Read 

 

- Ow_Write 

Ow_Reset

sub function Ow_Reset(dim byref port as word, dim pin as word) as word

Description Issues OneWire reset signal for DS18x20.
Parameters - 

port

: OneWire bus port 

- 

pin

: OneWire bus pin 

- 

0

 if the device is present 

- 

1

 if the device is not present 

Devices compliant with the Dallas OneWire protocol.

Ow_Reset(PORTF, 6)

None.