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Multi-Purpose IO Card

When you need a bunch of buttons. encoders and a display when designing your next project, but don’t want the mess of a breadboard.

When we are working on a prototype, we always need access to pushbuttons, encoders and even displays to test our ideas in the real world. This Multi-Purpose IO Card was designed to help me do just that…

What is on the PCB?
This PCB was designed with my particular work style in mind. I use a lot of I2C devices, IO Expanders, Displays and sensors. It would thus make sense to have I2C on the PCB, to control an OLED display, as well as a PCF8574 IO expander, that is used to drive a 4×4 Matrix Keypad. Two Rotary encoders, as well as another 4 standard push buttons completes the PCB

The features, summarised is as follows:1x Matrix Keypad (4×4) Controlled via an PCF8574 IO expander with selectable addressing.1x SSD1306 OLED I2C Display4x Momentary pushbuttons, configured to be used with internal pullups – i.e pushing the button pulls the GPIO LOW2x Rotary Encoders, with integrated Pushbutton, also configured as Active LOW

The board has all of the connectors and jumpers on the back, making it possible to mount it to an enclosure as a control panel.

I have also provided an additional I2C header to make it possible to add additional devices to the I2C bus easily”

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