I own Raspberry Pi 2 B and I wanted to create something like Novation's Launchpad. How many buttons can I connect through GPIO at once?

2 Answers 2


Without add-ons and using the Pi's gpios 26 (or 28 if you are happy to forgo HAT compatibility).

If you buy something like a MCP23017 (port expander) you can have 100s. They provide 16 additional gpios each and 8 may be connected to an I2C bus (the I2C bus is Pi pins 3 and 5).


I'm not sufficiently familiar with the Pi, but if you have 8 bits out and 8 bits in, and a bunch of signal diodes, you can implement a software keyboard encoder for a 64-switch matrix...

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