46.2.4 Signal DescriptionsTable 46-3. SignalsSignal Name 2-Wire Scheme 4-Wire Scheme I/OSCL LPI2C clocklineSCL In 4-wire mode, this is the SCL input pin. I/OSDA LPI2C datalineSDA In 4-wire mode, this is the SDA input pin. I/OHREQ Host request If host request is asserted and the I2C bus is idle, then it will initiate an LPI2Cmaster transfer.ISCLS SecondaryI2C clock lineNot used In 4-wire mode, this is the SCLS output pin. IfLPI2C master/slave are configured to useseparate pins, then this the LPI2C slave SCLpin.I/OSDAS SecondaryI2C data lineNot used In 4-wire mode, this is the SDAS output pin. IfLPI2C master/slave are configured to useseparate pins, then this the LPI2C slave SDApin.I/O46.2.5 Wiring optionsLPI2C can be used to implement 2-wire or 4-wire I2C serial busses.Printed Circuit Board (PCB)I²C (Inter-Integrated Circuit) 2-Wire Serial BusMicrocontroller 2-wireperipheraldevice #12-wireperipheraldevice #22-wireperipheraldevice #3Data (SDA)Clock (SCL)MCUSlave Slave SlaveFigure 46-5. 2-Wire schemeSome applications can provide a lot of load and noise on the I2C bus; to ensure robust I2Coperations, a 4-wire interface with the MCU can be used, splitting the 2 lines into inputsand outputs. Using a few transistors, resistors and diodes, designers can make their owninexpensive line drivers.IntroductionMWCT101xS Series Reference Manual, Rev. 3, 07/20191414 NXP Semiconductors
