NXP expands I2C with Agile I/O

October 17, 2012 // By Nick Flaherty
NXP Semiconductors has developed technology to expand its two wire I2C interface to 8 or 16bits for keyboards, switches, LEDs, displays, or even stepping motors.

It has launched a new family of 8bit and 16bit GPIO devices featuring “Agile I/O” that expands the two wires to 8 or 16 general-purpose I/O pins to save valuable pins on the microprocessor or custom ASIC and provide voltage shifting. The new I2C Agile I/O expanders include an interrupt pin that reports back to the control processor when an input has changed state, a hardware reset pin to return the device to its default state without powering down the part and two power-supply pins to enable simple level-shifting between different voltage domains.
The Agile I/O GPIO expanders further reduce the bill of materials (BoM) by eliminating external components and minimizing the PCB space required, and simplify firmware development by capturing real-time events and eliminating software latencies, thus improving reliability.
The 16 new devices include eight industry-standard I2C GPIO expanders, as well as eight devices with additional Agile I/O functions. Providing a wide voltage range including level-shifting capabilities and support for voltages as low as 1.65V, the new GPIO expanders offer significant cost savings as replacements for existing 2.3 to 5.5V GPIO devices. With the same pin-out and register sets as industry-standard PCA95xx devices, the new GPIOs can also easily be interchanged in the same sockets, even in mid-cycle refresh.
The Agile I/O includes software-programmable features including an input latch to retain the input state, internal pull-up and pull-down resistors, an interrupt mask which reduces interrupt traffic to the microcontroller and improves interrupt service response, interrupt register reports to identify which input actually caused an interrupt and an output drive strength control to minimize system noise when multiple outputs switch simultaneously.“From consumer devices to industrial equipment, embedded systems today are run by increasingly complex microprocessors and ASICs. Adding more input/output pins to interface with the user and other ICs, however, translates to bigger and more expensive packages. A more elegant, cost-effective solution is to make the most of the I2C-bus