Smart, simple solutions for the 12 most common design concerns 2 NXP I C-bus solutions 20142 I C-bus: The serial revolution By replacing complex parallel interfaces with a straightforward yet powerful serial SDA 2 structure, the I C-bus revolutionized chip-to-chip communications. SCL uC 2 Invented by NXP (Philips) more than 30 years ago, the I C-bus uses a simple two-wire format to carry data one bit at a time. It performs inter-chip addressing, selection, control, and data transfer. Speeds are up to 400 kHz (Fast-mode), 1 MHz (Fast-mode Plus), 3.4 MHz (High Speed-mode), or 5 MHz (Ultra Fast-mode). 2 Parallel Interface I C Serial Interface 2 The I C-bus shrinks the IC footprint and leads to lower IC costs. Plus, since far fewer copper traces are needed, it enables a smaller PCB, reduces design complexity, and lowers system cost. A/D MCU I/O LCD RTC MCU D/A A 0 New A 1010A A A R/W 1 1010011 R/W 2 1 0 function A 2 New function address New function address as assigned 2 2 I C-bus devices are available in a wide range of functions. Each slave device has its own I C-bus address, selectable using address pins set high (1) or low (0). Information is transmitted byte by byte, and each byte is acknowledged by the receiver. There can be multiple devices on the same bus, and more than one IC can act as master. The master role is typically played by a microcontroller. Write data Master Slave SDA transmitter receiver S slave address W A data A data A P SCL < n data bytes > Read data SDA receiver transmitter S slave address R A data A data A P SCL < n data > last data byte The master always sends the clock bytes S = Start condition R/W = read/write A = Acknowledge A = Not acknowledge P = Stop condition