User manual

mikroC PRO for PIC32
MikroElektronika
383
OneWire Library
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
Prototype
unsigned int Ow_Reset(unsigned int *port, unsigned int pin);
Description Issues OneWire reset signal for DS18x20.
Parameters - port: OneWire bus port
- pin: OneWire bus pin
Returns - 0 if the device is present
- 1 if the device is not present
Requires Devices compliant with the Dallas OneWire protocol.
Example
// Issue Reset signal on One-Wire Bus connected to pin RF6
Ow_Reset(&PORTF,6);
Notes None.