GPIOs Expand I2C Bus Wires Into 8 Or 16 Pins

Eindhoven, Netherlands: A new family of 8- and 16-bit general-purpose I/O devices (GPIOs) from NXP Semiconductors expand the two wires of the I²C bus into eight or 16 GPIO pins. These can interface to keyboards, switches, LEDs, displays, or even stepper motors, which saves pins on the microprocessor or ASIC. Eight of the 16 new devices in the family include NXP’s Agile I/O functions, integrating the most commonly needed functions in embedded systems.

Agile I/O incorporates 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 pins to enable simple level-shifting between different voltage domains. Agile I/O also incorporates software programmable features, such as an input latch to retain the input state, internal pull-up and pull-down resistors, and an interrupt mask that reduces interrupt traffic to the microcontroller and improves interrupt service response.

Equipped with a wide voltage range including level-shifting capabilities and support for voltages as low as 1.65V, the GPIO expanders can replace 2.3V to 5.5V GPIO devices. They have the same pinout and register sets as standard PCA95xx devices, which allows for easy interchanging in the same sockets, even in mid-cycle refresh.

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