NXP Semiconductors has unveiled a new family of 8-bit and 16-bit GPIO devices featuring “Agile I/O” – an innovative option integrating the most commonly needed functions in embedded systems. The GPIOs expand the two wires of the I2C-bus into 8 or 16 general-purpose I/O pins that can interface to keyboards, switches, LEDs, displays, or even stepping motors, saving valuable pins on the microprocessor or custom ASIC. The Agile I/O GPIO expanders help to reduce the bill of materials (BoM) by eliminating external components and minimising 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.
“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 with its two pins, and adding any number of Agile I/O GPIO expanders to handle interface duties and reduce the number of external components required,” said Steve Blozis, international product marketing manager, interface products, NXP Semiconductors. “By working to 1.65V and supporting a wider voltage range, our latest generation of GPIO devices also addresses the industry shift toward lower voltage applications.”
Unique “Agile I/O” features include the incorporation of many useful functions commonly added in system applications, the new I2C Agile I/O expanders offer the following as standard integrated hardware features: 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.
In addition, the Agile I/O includes important 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 minimise system noise when multiple outputs switch simultaneously.