1wire

Table of Contents

• 1wire.readbit
• 1wire.readbyte
• 1wire.reset
• 1wire.writebit
• 1wire.writebyte

1wire.readbit()

The 1wire.readbit() function reads a bit from the one-wire bus and returns it.

Syntax

u8 1wire.readbit(u8 pin); // P8 and P32

Parameters

Param	Type	Desc
pin	8 bit integer	pin to which the one-wire bus is connected.

Returns

The value of the bit read from the one-wire data line: 0 or 1

Example

u8 OneWireRead(u8 pin)
{
	u8 i, value = 0;	
	for (i=0; i<8; i++)
	{
		if (1wire.readbit(pin))	// reads byte in, one bit at a time
		{
			value |= 0x01 << i;	// and then shifts it left
		}
	}
	return(value);
}

Notes

Relates

• 1wire.readbyte
• 1wire.reset
• 1wire.writebit
• 1wire.writebyte

1wire.readbyte()

The 1wire.readbyte() function reads a byte from the one-wire bus and returns it.

Syntax

u8 1wire.readbyte(u8 pin);  //(P8 and P32)

Parameters

Param	Type	Desc
pin	8 bit integer	pin to which the one-wire bus is connected.

Returns

The value of the byte read from the one-wire data line.

Example

// example for P8 - 18f4550
while (busy == 0)		// Wait while busy ( = bus is low)
    busy = 1wire.readbyte(0);	// One-Wire bus is on pin 0 (RB0)

Notes

Relates

• 1wire.readbit
• 1wire.reset
• 1wire.writebit
• 1wire.writebyte

1wire.reset()

The 1wire.reset() function performs a reset on the one-wire bus and returns the presence detect.

Syntax

u8 1wire.reset(u8 pin);  //(P8 and P32)

Parameters

Param	Type	Desc
pin	8 bit integer	pin to which the one-wire bus is connected.

Returns

Returns 1 if no presence detect was found, 0 if presence detect was found. If there is a one-wire device on the one-wire bus it pulls the DQ line low (0). If there is no one-wire device on the one-wire then the pull-up resistor ensures that the one-wire bus remains high (1).

Example

if (1wire.reset(0)) return FALSE;

Notes

Relates

• 1wire.readbit
• 1wire.readbyte
• 1wire.writebit
• 1wire.writebyte

1wire.writebit()

The 1wire.writebit() function writes a bit to the one-wire bus.

Syntax

void 1wire.writebit(u8 pin, u8 val);  //(P8 and P32)

Parameters

Param	Type	Desc
pin	8 bit integer	pin to which the one-wire data bus is connected.
value	8 bit integer	value to be written ( 0 or 1 )

Returns

None.

Example

void OneWireWrite(u8 pin, u8 val) // P8 and P32
{
    u8 i, temp;
    for (i=0; i<8; i++)			// writes byte, one bit at a time
    {
        temp = val >> i;		// shifts val right 'i' spaces
        temp &= 0x01;			// copy that bit to temp
        1wire.writebit(pin, temp);	// write bit on the one-wire bus
    }
}

Notes

Relates

• 1wire.readbit
• 1wire.readbyte
• 1wire.reset
• 1wire.writebyte

1wire.writebyte()

The writebyte() function writes a byte to the one-wire bus.

Syntax

void 1wire.writebyte(u8 pin, u8 val);  //(P8 and P32)

Parameters

Param	Type	Desc
pin	8 bit integer	pin to which the one-wire data bus is connected.
value	8 bit integer	value to be written

Returns

none

Example

Notes

Relates

• 1wire.readbit
• 1wire.readbyte
• 1wire.reset
• 1wire.writebit