OWRDBIT Pin, Bit Var

Function
Reads one bit from a 1-Wire bus.

• Pin  is any SX I/O pin (RA.0 .. RA.7, RB.0 .. RB.7, RC.0 .. RC.7, RD.0 .. RD.7, RE.0 .. RE.7).
• BitVar is a bit variable that will hold the 1-Wire Read Slot value.

Quick Facts

	All SX Models
Special Notes	The DQ pin (specified by Pin) must have a 4.7 kΩ pull-up resister.
	1-Wire commands require a FREQ setting of 4 MHz or higher.

Explanation
Some 1-Wire transactions require reading data from the device. While this is typically handled with OWRDBYTE, SX/B supports bit access with the OWRDBIT instruction. A 1-Wire read is accomplished by generating a brief (5 µS) low-pulse and sampling the DQ pin within 15 µS of the falling edge of the pulse. This is called a "Read Slot." The diagram and table below details the Read Slot sequence generated by the SX with OWRDBIT.

Note	Timing	Description
A	5 µS	Initiate Read Slot (SX master)
B	10 µS	Delay before sampling DQ
C	~ 60 µS	Read Slot recovery

Related instructions: OWRESET, OWRDBYTE, OWWRBIT, and OWWRBYTE