QGPIO Adds Eight GPIO Pins, Status LEDs to Any Qwiic- or I2C-Compatible Project
With KiCad file available for those looking to customize, Greg Steiert's QGPIO is a compact and simple way to add pins to your project.
Developer Greg Steiert has released the design for a simple, open source Qwiic expander, compatible with any I2C bus, that adds eight general-purpose input/output (GPIO) pins per board.
"This is a handy general purpose input/output Qwiic board," Steiert describes. "It provides 8 GPIO each with an LED indicator, and goes to a pin in a dual row 100mil header. The LEDs provides a nice visual output. The second row on the header is grounded, so jumpers can be used to drive the pins low for basic inputs. The 100mil pitch headers are also convenient for connecting to external circuits as well. The interrupt and VCC pins also have their own LEDs and header pins. There are two Qwiic connectors for pass through connections."
"Now that all my boards are using Qwiic connectors, I'm always looking for a Qwiic peripheral board to check out the hardware/tools/libraries. What I a really want is a simple device that can provide some quick feedback. That is why I chose the PCF8574, it is just about the simplest I2C device you will find. There is no secondary addressing, a read always returns the physical state of the pins, and a write always updates the open drain outputs. As long as you don't force the pins high, you don't even need to worry about contention since the outputs are open drain."
Steiert has released his design under an unspecified open hardware licence, offering the KiCad project file for those who find the board — "only as large as it needs to be," he explains — needs a tweak for their particular use case. "If you think it is too small or wish there were mounting holes, go ahead and modify to your hearts content."
More details on the board can be found on the Hackaday.io project page, with files available to download on GitHub; the board can also be ordered from OSH Park.