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GPIOs expand I2C from two wires to 8/16-pins

Posted: 19 Oct 2012     Print Version  Bookmark and Share

Keywords:GPIO  I/O  embedded  I<sup>2</sup>C 

NXP Semiconductors NV launches the Agile I/O innovation in a family of 8bit and 16bit GPIO devices. Agile I/O technology is said to integrate the most commonly needed functions in embedded systems. With it, GPIOs can expand the two wires of the I2C -bus into eight or 16 GPIO pins that can interface to keyboards, switches, LEDs, displays, or even stepping motors, saving valuable pins on the microprocessor or custom ASIC.

There are 16 new devices with the innovation, eight industry-standard I2C GPIO expanders and eight devices with additional Agile I/O functions. They 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 2.3V 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.

In addition, the Agile I/O GPIO expanders cut BOM by doing away with external components and minimising the PCB space required. They also simplify firmware development by capturing real-time events and eliminating software latencies.

In terms of hardware, they integrate 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.

Software-programmable features of the GPIOs include 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; an interrupt register that identifies which input actually caused an interrupt; an output drive strength control to minimise system noise when multiple outputs switch simultaneously.

The new GPIO expanders will be offered in TSSOP, as well as 0.5mm pitch QFN package options, with the first product types available immediately.

The PCA(L)6408AHK is also released in a smaller 0.4mm pitch QFN and the PCA(L)6416AEV in 0.5mm pitch BGA. The Agile I/O version of both of these devices will also be released in a 0.4mm pitch BGA package for the growing thin portable market.

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